Clutch replace

[Bitsyncmaster]

Do I remove the cross gate cable from the bracket and leave the bracket in place or remove the bracket? Does the end of that cable have a pin that just pushes out?

[David T]

A lot depends on how you are taking the trans out. if you are doing it on jackstands you want a lot more room than if you are doing it on a lift. There is a pin.

[DMC5180]

Do I remove the cross gate cable from the bracket and leave the bracket in place or remove the bracket? Does the end of that cable have a pin that just pushes out?

When I’ve pulled the trans, I disconnected the cross-gate cable clevis pin. It has a tiny hairpin clip in it. I remove the pivot bell crank and bracket the clevis is attached to. Then I remove the back cover bolts that hold the cable support bracket. Do not remove the bracket from the cable. This will save you lots of unnecessary adjustment headache later. Tie-wrap the cable and bracket up out of the way.


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[Bitsyncmaster]

Well I pulled the cross gate cable out of the bracket. That required pulling one bold from the back to let the cable come back from the bracket. The top of the bracket still on the transmission is about 4 or 5 inches from the back of the frame. Don't know if that is enough clearance to back the transmission out.

I broke the 4 bolts loose that hold the transmission to the engine. Think all I need to do now is disconnect the clutch line and make an engine support before attempting the removal.

[DMC5180]

I’ve never attempted trans removal with the upper cable bracket attached to the back cover. If I were you, I would remove it first. It’s one less thing to cause problems if things go wrong.


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[Bitsyncmaster]

I’ve never attempted trans removal with the upper cable bracket attached to the back cover. If I were you, I would remove it first. It’s one less thing to cause problems if things go wrong.


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Thanks. Is there a bolt on top? Can not see even with a mirror (old eyes can't focus that distance anymore).

[DMC5180]

You will need too support the engine and even push up on it a couple it an inch or two. Otherwise when the counterweight of the transmission is removed the engine will drop at the rear. You will notice that with the trans mounting brackets removed, that the engine and trans assembly is remarkably balanced front to back on the engine mounts.


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[DMC5180]

Thanks. Is there a bolt on top? Can not see even with a mirror (old eyes can't focus that distance anymore).

Yes, the bolt head is partially obscured by the bracket gusset. I’ve had the best success using a 1/4” drive ratchet with a 6” or longer extension my extensions are the wobble type so thry work better with the slight off angles. Try too borrow your wife’s bathroom hand mirror or compact mirror to get a better look at things.


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[DMC5180]

Yes, the bolt head is partially obscured by the bracket gusset. I’ve had the best success using a 1/4” drive ratchet with a 6” or longer extension. The ratchet extensions I use are the wobble type they work better with the slight off angles. Try too borrow your wife’s bathroom hand mirror or compact mirror to get a better look at things.


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[Bitsyncmaster]

I got the top bracket off. There were two bolts 13mm socket on extension worked. I just found them by feel. One of the bolts was tight coming all the way out so I guess it was never removed before. I do think I will pull the push rod off the bell crank to get it out of the way.

[Bitsyncmaster]

I got all the mount bolts loose, the push rod removed, tied the shift cable out of the way and have the engine bolted to a 2x4 to keep it from rocking down. I did that engine support because I did not want anything under the engine in the way of completing the removal.

Do I need to remove the E brake cable that crosses the tran? Or can it just push out of the way?

Will need to disconnect the clutch line and then remove all the bolts while I have the trans jack supporting the trans.

[DMC-81]

I got all the mount bolts loose, the push rod removed, tied the shift cable out of the way and have the engine bolted to a 2x4 to keep it from rocking down. I did that engine support because I did not want anything under the engine in the way of completing the removal.

Do I need to remove the E brake cable that crosses the tran? Or can it just push out of the way?

Will need to disconnect the clutch line and then remove all the bolts while I have the trans jack supporting the trans.

Yes, you'll need to remove the e-brake cable from the passenger side caliper. I just removed the cable ( not the bracket) and threaded it back through the aluminum air deflector and out of the way.

For the clutch, I didn't have to disconnect the line. I unbolted the slave and the hard line bracket (106320) and tied it out of the way ( on the driver's side lower link) .

[DMCMW Dave]

I just found them by feel.

Exactly, 100% by feel on these bolts. But as you found there is room for them to come out.

[Bitsyncmaster]

Yes, you'll need to remove the e-brake cable from the passenger side caliper. I just removed the cable ( not the bracket) and threaded it back through the aluminum air deflector and out of the way.

For the clutch, I didn't have to disconnect the line. I unbolted the slave and the hard line bracket (106320) and tied it out of the way ( on the driver's side lower link) .

My brake cable won't fit through the slot on the brake cable clamp. Yes I see there is a machined area on the cable threaded housing but it won't pass through the slot which is to small to let that machined area pass through.

Is there a way to remove the other end (at the e-brake handle? Or do I have to "machine" that slot wider somehow?

[DMC-81]

My brake cable won't fit through the slot on the brake cable clamp. Yes I see there is a machined area on the cable threaded housing but it won't pass through the slot which is to small to let that machined area pass through.

Is there a way to remove the other end (at the e-brake handle? Or do I have to "machine" that slot wider somehow?

I'm not sure about the handle end, but on the caliper end, if you remove the nut and washers on the outboard end ( assuming the handle end is relaxed) there is a spot in the cable where it will slide through the slot in the bracket. The spot is under spring tension so you have to move the cable inward against the bracket with the nut fully released, and then slide it sideways.

One other tip: I counted threads on the cable for reference (and/or took a picture) before removing the nuts so I could get the cable back in the ballpark of adjustment afterwards.

[Bitsyncmaster]

I'm not sure about the handle end, but on the caliper end, if you remove the nut and washers on the outboard end ( assuming the handle end is relaxed) there is a spot in the cable where it will slide through the slot in the bracket. The spot is under spring tension so you have to move the cable inward against the bracket with the nut fully released, and then slide it sideways.

One other tip: I counted threads on the cable for reference (and/or took a picture) before removing the nuts so I could get the cable back in the ballpark of adjustment afterwards.

Yes I saw that spot in the cable but my bracket was not machined wide enough in the slot. I guess some brackets were made this way and they must have fixed it later. Anyway, I did get it machined using my Dremal and a small cutter. Not sure if I damaged the threads on the cable housing so I may have to replace it if I did. It does look like the top of that slot was bent up when they assembled the car.

[Jason]

Yes, you'll need to remove the e-brake cable from the passenger side caliper. I just removed the cable ( not the bracket) and threaded it back through the aluminum air deflector and out of the way.


I did my clutch recently, and didn't have to disconnect the parking brake cable. I was able to just push it forward past the front of the transmission. It did mean I had to have one hand pushing on the cable while the other had was lowering the transmission jack.

[Bitsyncmaster]

I did my clutch recently, and didn't have to disconnect the parking brake cable. I was able to just push it forward past the front of the transmission. It did mean I had to have one hand pushing on the cable while the other had was lowering the transmission jack.

I suspect that is how it's done on a lift when two people can help when dropping the transmission. I'm pretty sure my clutch was replaced prior and that brake cable was never removed.

[DMC-81]

I tend to agree. I’m sure there is other ways to do it, but the manual states to remove it, and I found little room to slide the gearbox forward without having to clear the cable. Plus if you are by yourself, you’ll want to get everything out of the way to make things as easy as possible.

But, whatever works for you.

[PJ Grady Inc.]

I tend to agree. I’m sure there is other ways to do it, but the manual states to remove it, and I found little room to slide the gearbox forward without having to clear the cable. Plus if you are by yourself, you’ll want to get everything out of the way to make things as easy as possible.

But, whatever works for you.

The fastest and easiest way to disconnect the cable is is to leave the threaded adjuster undisturbed and simply remove the 19mm locknut and small bolt from the brkt to hub and the 10mm locknut on the cable end. This is much faster than the other method.
Rob

[Bitsyncmaster]

The fastest and easiest way to disconnect the cable is is to leave the threaded adjuster undisturbed and simply remove the 19mm locknut and small bolt from the brkt to hub and the 10mm locknut on the cable end. This is much faster than the other method.
Rob

Now you tell me.:bigcry:

[DMC-81]

The fastest and easiest way to disconnect the cable is is to leave the threaded adjuster undisturbed and simply remove the 19mm locknut and small bolt from the brkt to hub and the 10mm locknut on the cable end. This is much faster than the other method.
Rob

:thumbup: Cool. I was motivated by not removing the bracket and the air deflector with my approach.

Dave, when you get into the job and find that you need other things, Rob has some great transmission parts that are hard or impossible to find elsewhere.

NOS clutch folks, seals, etc.

[Bitsyncmaster]

:thumbup: Cool. I was motivated by not removing the bracket and the air deflector with my approach.

Dave, when you get into the job and find that you need other things, Rob has some great transmission parts that are hard or impossible to find elsewhere.

NOS clutch folks, seals, etc.

From the looks of it, there is oil that looks like dripping from the bell housing. So I will probably need some seals. I also saw the rubber bellow where the shift linkage goes is torn and a little oil there. It's nice I'm not rushed to get this done. Was planning on pulling the transmission in the morning but turns out I have to take my granddaughter to camp.

[Bitsyncmaster]

Six bolts to go for dropping it. Two on each mount and the bottom two for bell housing to engine. There does not seem to be any pressure on the mount bolts yet so it seems well balanced. Now I stuck the jack under there and ready to chain the transmission to the jack.

It looks like if you want to pull the transmission from under the car I will need to slide it off the jack since the jack sits so high even all the way down. And or I may have to jack the car up higher.

[Bitsyncmaster]

Can't get the transmission and engine to separate. Any tricks to do it? I'm using a pry bar from the frame to bottom of the bell housing and trying that with different pressures on my transmission jack (higher and lower).

[DMC5180]

Can't get the transmission and engine to separate. Any tricks to do it? I'm using a pry bar from the frame to bottom of the bell housing and trying that with different pressures on my transmission jack (higher and lower).

Have you removed all 3 protection plates on the engine side of the flywheel?

Have you been able to create a gap in the mating surfaces of 1/8”-1/4”?

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[DMC-81]

Can't get the transmission and engine to separate. Any tricks to do it? I'm using a pry bar from the frame to bottom of the bell housing and trying that with different pressures on my transmission jack (higher and lower).

Double check that everything is disconnected and if the drivetrain is level, it should only need a gentle pry. I found that the forward end of the transmission tended to tilt down off horizontal plane so I needed to use a wooden shim to correct that. If it does this, the input shaft is getting hung up on the pilot bearing.

http://dmctalk.org/attachment.php?attachmentid=55798&d=1522255258

When the level is right it just separates easily. Look for an even gap vertically between where the engine and transmission meet. If it is not even, then that needs to be corrected.

[Bitsyncmaster]

I got it separated. Just took a break and when I went back it popped right off. I do have to lift the car higher to be able to move the transmission out of the way.

[DMC5180]

I got it separated. Just took a break and when I went back it popped right off. I do have to lift the car higher to be able to move the transmission out of the way.

Not sure how high your jack stands are, but mine are 16” full up. At that height, I had too slide it off the trans jack onto the floor (cardboard under it) then it slid out without any trouble using space in the wheel opening.


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[Bitsyncmaster]

Not sure how high your jack stands are, but mine are 16” full up. At that height, I had too slide it off the trans jack onto the floor (cardboard under it) then it slid out without any trouble using space in the wheel opening.


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Well I have 2 6"x6" blocks under each rear tire (makes me feel safer when under the car) and my jack stands seem maxed out with one 2"x6" under the jack point. I put two 2"x6"s between the tires and ramps. It still is not high enough so I will need to slide it off the jack also to get it out.

By the way, anyone else pulling the transmission, pull all the shift bracket off. I had left the pivot bracket on an it hit the coolant pipes. I did get it dropped but it took a lot of extra work.

Looks like the transmission main seal is not leaking.

What are these blocks held on the pressure plate?

[DMC5180]

You have a Centerforce clutch. The blocks are added Flyweights. I have the same unit.


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[Bitsyncmaster]

You have a Centerforce clutch. The blocks are added Flyweights. I have the same unit.


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I will have to see why it failed. I will measure the disk for wear when I get it removed. Taking the day off after working on it for 4 hours this morning.

[DMC-81]

Not sure how high your jack stands are, but mine are 16” full up. At that height, I had too slide it off the trans jack onto the floor (cardboard under it) then it slid out without any trouble using space in the wheel opening.


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+1. Here’s where I removed the box to minimize the height of lifting the car:

http://dmctalk.org/attachment.php?attachmentid=55711&d=1521681616

[Bitsyncmaster]

Not sure how high your jack stands are, but mine are 16” full up. At that height, I had too slide it off the trans jack onto the floor (cardboard under it) then it slid out without any trouble using space in the wheel opening.


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I dropped (literally) my transmission off the jack. I had it centered on the jack to far forward. I will find the CG so when I put it back in it may go in better. It's going to take some maneuvering to get that back on the jack. Also the hold down chain on my jack has one end just fitting over a "fork". That had slipped off so probably better to use a bolt and nut on each end of the chain.

I need to run to the store to get a 6 mm "Allen" head socket for the pressure plate removal. Think I need to use an impact on those bolts. I did get one to break free but don't want to skin any more knuckles.

[Bitsyncmaster]

Old clutch plate is 0.290" thick and new one is 0.300" inch thick. No wear on flywheel or old pressure plate so what caused my clutch to fail?

[DMC5180]

Old clutch plate is 0.290" thick and new one is 0.300" inch thick. No wear on flywheel or old pressure plate so what caused my clutch to fail?

Define, fail? Do you mean slipping from a standing start?

Does your flywheel surface have a slightly raised surface for the friction material aka the step?


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[Bitsyncmaster]

Define, fail? Do you mean slipping from a standing start?

Does your flywheel surface have a slightly raised surface for the friction material aka the step?


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It would slip after about one hour driving. Never did this before. Was going about 60 MPH and suddenly the RPM jumped. Thought maybe it slipped out of gear but a short time after it did it again. I stopped and it would work again, and again.........
It would do it even in a lower gear. So I turned around and got maybe five miles with about 5 stops and called a tow truck.

There is a very slight raised surface at the friction location. How much should that step be? I can mice how much that step is with a depth mice.

Another thing I should do is measure the surface of the pressure plate to the fiction surface on it.

[Bitsyncmaster]

The new pressure plate mount to friction surface is 0.201". The old pressure plate mount to friction surface is 0.205".

So not much difference there.

Flywheel step is 0.016".

[FABombjoy]

Could it have been a bad master? Stuck plunger blocking the passage to the reservoir as the fluid heated up?

[Bitsyncmaster]

Could it have been a bad master? Stuck plunger blocking the passage to the reservoir as the fluid heated up?

Clutch was working.....No grinding, no problem going through the gears at stops. If the hydraulics failed it would keep the clutch engaged. But I see your thought of it building a pressure that would not release. When it failed I did open the bleed niple on the side of the road and let some fluid out but that did not fix my problem.

[Bitsyncmaster]

While waiting to find out what caused my clutch to slip, I want to pull the flywheel to see if I need to replace the main seal on the engine. The book says those bolts on the flywheel used locktite. So would an impact wrench get those bolts out without using heat?

I'm wondering if my flywheel was resurfaced and therefor has and insufficient step. The step would move the clutch assembly closer to the flywheel.

[DMC5180]

The bolts have Blue Loctite. You won’t have any issue removing them. The bolt pattern is not evenly spaced. So the flywheel can only be installed one way for indexing.

The .016 step sounds correct as I recall.

Do you recall at what point in the pedal travel that the clutch would engage/disengage? High, middle or low?

Do you have the factory solid pedal link or the adjustable one (PJ Grady)?

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[DMC-81]

While waiting to find out what caused my clutch to slip, I want to pull the flywheel to see if I need to replace the main seal on the engine. The book says those bolts on the flywheel used locktite. So would an impact wrench get those bolts out without using heat?

I'm wondering if my flywheel was resurfaced and therefor has and insufficient step. The step would move the clutch assembly closer to the flywheel.

Rob Grady or definitely DMCH can verify the proper step spec. I don't have it in my notes, other than this picture. I remember running my finger over the step, and it seemed to be more than .016" , but I could be wrong.

Also, since you mentioned oil dripping from the bell housing, did you notice any oil on the friction plate or flywheel? Just checking that off for a potential theory for the clutch slipping. It's weird that it slipped/failed after an hour or so.

http://dmctalk.org/attachment.php?attachmentid=49665&d=1490062026

[Bitsyncmaster]

Rob Grady or definitely DMCH can verify the proper step spec. I don't have it in my notes, other than this picture. I remember running my finger over the step, and it seemed to be more than .016" , but I could be wrong.

Also, since you mentioned oil dripping from the bell housing, did you notice any oil on the friction plate or flywheel? Just checking that off for a potential theory for the clutch slipping. It's weird that it slipped/failed after an hour or so. [/IMG]

I would think anyone that gets the flywheel resurfaced would need to know the proper step. Yes I also thought about oil causing the slip. I did not see any signs of oil on any of the friction surfaces but it has been sitting about 10 months since it happened. I really don't want to put things back together without finding what caused the problem. I'm wondering if the spring pressure pressing on the friction surface is at fault. Not sure how I could test that.

[Bitsyncmaster]

Just looking over things and I find the shaft on the transmission can move side to side quite a bit. I think I saw this question asked before somewhere but can't find that post. Since that shaft couples to the engine drive shaft I guess that large movement is normal.

Also see my boot on the clutch slave is torn.

Also the "bellows" boot on the shift linkage shaft just flops around so there is a little oil leak there. Don't see what hold that boot tight.

Is this normal on the arm to the shift linkage (photo attached)? I don't see this in the DMC books.

[Bitsyncmaster]

Flywheel bolts had red locktite on them. No problems removing them with impact wrench.

Note the friction surface still shows that it was machined on a mill with a fly cutter. So the step would have to done on a lathe or mounted on a rotary table on the mill. No machine marks there.

[DMC-81]

Just looking over things and I find the shaft on the transmission can move side to side quite a bit. I think I saw this question asked before somewhere but can't find that post. Since that shaft couples to the engine drive shaft I guess that large movement is normal.

Also see my boot on the clutch slave is torn.

Also the "bellows" boot on the shift linkage shaft just flops around so there is a little oil leak there. Don't see what hold that boot tight.

Is this normal on the arm to the shift linkage (photo attached)? I don't see this in the DMC books.

Yes, that bellows movement is normal. There is a lip seal, 103049 (http://store.delorean.com/p-8504-lip-seal.aspx) that provides the shaft seal, pictured here:
http://dmctalk.org/attachment.php?attachmentid=52363&d=1499226817

I would suggest replacing both while the transmission is out since the are already leaking.

That picture of the mic tool on the flywheel step looks more normal to me. I would agree to double check it .

I too was wondering about the fingers and the weights failing (most likely due to heat?)as a potential cause , but I don't know about the weaknesses in Centerforce clutch package.

[Bitsyncmaster]

That picture of the mic tool on the flywheel step looks more normal to me. I would agree to double check it .

The photo makes that step look big but it really is just 0.016" which is about the thickness of two hairs.

[DMC5180]

I fairly positive that the Centerforce clutch is nothing more than a Stock Valeo clutch with a paint job and the weight blocks added. I noticed Daves clutch had 6 - 98 hand written on it. My guess is thats when it was installed June of 98. I think I remember seeing Valeo stamped on the components of my clutch when I installed it about 20 years ago now.

IIRC: If you buy a Centerforce clutch now, you’re just getting a paint job only. They don’t add the weights anymore.

As far as a leaking clutch slave goes, I helped a friend do the clutch on his car many years back. It was very obvious he had leaking issues. The friction plate was a total mess of wet black goo. Basically friction dust mixed with fluid. The flywheel and pressure plate surfaces were deeply grooved from slippage.


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[Ron]

Dave, I think you may have missed Dennis' last post... I'm not sure it is possible, but if your D has an adjustment added for the pedal end (or both), I can imagine where all of the slack was taken out, making it release at extreme top pedal. Being too tight, the master's piston may not have enough travel to allow the last bit of fluid to flow into the reservoir (shy of port). This would make the linkage virtually solid as with non-hydraulic systems. Then as the clutch wears, the plate arms/fingers move out taking up space, which means more fluid can't return. Again, I'm not sure it is possible as I have never installed one, but if the pedal adjustment was installed w/o removing the pedal stop ("required"), maybe the pedal is not able to rise as far as it should (3/4" higher than the brake pedal, after update), adding to the problem. The pressure plate assembly would not be able to fully release... On non-hydraulic systems, this usually results with the throw out bearing failing and/or the clutch not engaging fully, but acts up ~equally hot/cold. Adding fluid and parts expanding with heat might be just enough to cause the pressure plate to ease up and allow slippage.
(Upgraded lines wouldn't expand like old plastic ones....)
Sounds a bit far fetched/too coincidental even to me, but I can't think of anything else to throw into the pot that would explain it acting up ONLY when hot and under heavy load.

This is a weird one!

============

Rebuild shops can test the spring pressure, action,etc while assembled.

The movement in the shaft you mentioned might explain why you have always had trouble shifting into 1st or reverse mentioned in another thread (synchronizer alignment).

[Bitsyncmaster]

Yes my car has the adjustable link on the clutch pedal. The clutch pedal does sit higher than the brake pedal. I don't think there is a stop adjustment any more for the clutch (PO must have removed it). I have checked there was clearance at no pedal before.

My clutch would engage at lease about half the clutch throw. I've driven other cars and never noted a difference in the clutch.

It looks like the only wear is about 0.01" of the clutch disk.

I'm thinking it must be a problem with pressure plate. I'm still thinking of a way to test that.

I don't see how the weights worked on the centerforce pressure plate.

[DMC5180]

I don't see how the weights worked on the centerforce pressure plate.

It’s hard to know if the weights really do all that much in our application. The principal behind them is that they are a centrifugal flyweight. As the clutch spins, the weights try to fly outward, like what you would see in an old school ball weight governor, except in this case the effect is a counter force on the pressure plate spring that essentially makes the clutch pressure spring fingers harder to push inward to release the clutch disc. Actually I believe the Centerforce clutch concept originated in Drag racing too aid in dumping the clutch off the line at high rpm.


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[David T]

The weights allow the pressure plate and springs to have a little less pressure so the clutch pedal is a little easier to push and at higher revs the weights add more force to hold the clutch tighter so it won't slip with the reduced spring pressure. It is a noticeable difference. A shop that rebuilds a clutch will usually replace the springs in the pressure plate, check that it is flat, and grind if necessary. Reassemble and measure the force. For the friction disc they will remove the friction materiel and replace with new. No one rebuilds these anymore so you just get all new parts. A clutch kit consists of the friction disc, pressure plate, throwout bearing, pilot bearing, and alignment tool. Should try to get the pressure plate with the weights. There are plenty of "While you are there" kinds of things to do when you pull the transaxle so often, you are not "just" doing a clutch.

[Bitsyncmaster]

Looks like only half the weights were moving. All on one side. Maybe this is why centerforce stopped putting weights on their pressure plate. I still don't see the physics of how these moving weights affect pressure on the clutch disk.

I measured the distance from both pressure plates using the flywheel and new disk before the pressure plate is bolted down and both are about 0.157".

[DMC5180]

Like I said before, the effects of how this concept works would seem minimal at best in our application.

The throw out bearing, pivot fork and slave cylinder piston remain in constant contact. The only slack in the system might be between the piston and back of the cylinder bore. If there was no room for opposing movement, I don’t see how the weights could possibly flex the diaphragm spring fingers enough to appreciably effect force on the pressure plate. Even the illustration below notes the movements shown are exaggerated.

https://uploads.tapatalk-cdn.com/20180729/97d2ee48df8fe0b1cb6dd65248ae6337.png


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[Bitsyncmaster]

That is showing the force direction of the weight is almost up (0 deg).....Yes it is an exaggeration since the most force would be almost at 45 degrees.

Also with the weight closer to the fulcrum than shown it would also reduce the added force.

[DMC5180]

That is showing the force direction of the weight is almost up (0 deg).....Yes it is an exaggeration since the most force would be almost at 45 degrees.

Also with the weight closer to the fulcrum than shown it would also reduce the added force.

The CG of the weight blocks is offset so that it does create a bending moment on the diaphragm spring fingers under centrifugal loading, but the leverage arm is very short.


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[Bitsyncmaster]

Is this normal on the arm to the shift linkage (photo attached)? I don't see this in the DMC books.

So why do I have two arms on my linkage?

[DMC-81]

So why do I have two arms on my linkage?

Hi Dave, That’s normal. The second part is an extension 108295, that connects to the shift arm, like so:
http://dmctalk.org/attachment.php?attachmentid=55821&d=1522655707

[MPPDMC]

hi there is also the chance nothing is wrong with the clutch and the slip is in the coupler on the input shaft being stripped ?

[Bitsyncmaster]

Hi Dave, That’s normal. The second part is an extension 108295, that connects to the shift arm, like so:
http://dmctalk.org/attachment.php?attachmentid=55821&d=1522655707

Thanks. I was just wondering if a PO made that change. So I guess it gives more throw on the forward/back gear shift in the car.

[Bitsyncmaster]

Well I'm at a loss as to why I had the failure (suddenly no connection of engine to transmission). So I was not using the clutch and got a sudden failure.

I have not found any problem with the mechanical area of the clutch, pressure plate, flywheel. Yes maybe the step is less than it should be but don't think that would have caused the failure.

I'm more inclined to think the hydraulics did not release fully but I would think I would have noticed when stopping and going through the gears if the clutch was grabbing very with a very high pedal. Also I did bleed some clutch fluid when the problem happened and the problem remained. Even if the clutch master somehow jammed up I think I would have noticed when going through the gears.

My only thought is somehow the weights on my centerforce pressure plate jammed not releasing the clutch fully.

By the way it was early in the morning when the failure occurred so the air temp was nothing great. I also could drive my car into my garage when the tow truck dropped off my car at home. I also drove it up onto ramps when getting ready to drop the transmission.

[Bitsyncmaster]

Well I bolted the flywheel, disk and pressure plate together. I set the throwout bearing on to see if the weights could have jammed and there is no way they could have jammed the throwout bearing.

On a side observation the fingers are just about perpendicular to the disk so there is no way the centerforce design is going to help. Maybe a few degrees of up angle.

Now to test the spring force you could apply a measured weight to the pressure plate to just get it to seat. But I'm guessing that force would be hundreds of pounds since bolting it down takes quite a bit of torque.

[David T]

Well I'm at a loss as to why I had the failure (suddenly no connection of engine to transmission). So I was not using the clutch and got a sudden failure.

the way it was early in the morning when the failure occurred so the air temp was nothing great. I also could drive my car into my garage when the tow truck dropped off my car at home. I also drove it up onto ramps when getting ready to drop the transmission.

First time you mentioned this. There are 2 possibilities. One is of course the clutch. The other is something inside the transmission. Before re-installing the transmission you should try all of the gears by hand to make sure there is nothing wrong with it. As for the clutch, it is possible the hydraulics did not fully release allowing the clutch to engage. The usual failure of the clutch is wear, the friction disc gets worn down to the rivets and the rivets score the pressure plate and/or the flywheel and the clutch slips under load. Rare to fail with complete disengagement. In cases where I have seen this it is often due to the clutch hydraulics overextending the throwout bearing and it gets mechanically stuck. Sounds like the clutch is not worn out so you must figure out what went wrong before you reassemble.

[Bitsyncmaster]

Just playing with the transmission. So I assume the lever on the transmission has three positions but when I move it by hand it seems to only go full forward or full revers. That would relate to the forward, neutral and back movement of the shift stick in the car.

I also assume the lever has four positions pushing in or out on the shaft of the shift lever. That would relate to your four left right movements of the shift stick in the car.

Just want to know if my thinking of how it works is correct.

[DMC5180]

You are correct in your thinking.


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[DMC-81]

Well I'm at a loss as to why I had the failure (suddenly no connection of engine to transmission). So I was not using the clutch and got a sudden failure.
Snip
By the way it was early in the morning when the failure occurred so the air temp was nothing great. I also could drive my car into my garage when the tow truck dropped off my car at home. I also drove it up onto ramps when getting ready to drop the transmission.



hi there is also the chance nothing is wrong with the clutch and the slip is in the coupler on the input shaft being stripped ?

I just wanted to highlight this suggestion as something to check. It would certainly cause a sudden disconnection, but not the ability to drive it a bit afterwards, unless the stripped splines (or crack/break) somehow caught again, allowing slow speed/low torque motion.

With the transmission in first gear and then in reverse, you should be able to fairly easily turn the input shaft (use a shop cloth around the shaft or the clutch disk) causing the drive flanges to turn. Then you can quickly turn it one way and the other (back and forth) and see if the drive flanges react in a fairly direct manner. Also check for any looseness or noise with these 2 tests.

I did this in every gear as a test after I reassembled my gearbox.

[Ron]

By the way it was early in the morning when the failure occurred so the air temp was nothing great.Was this during the time(s) previously mentioned? ...Your D had been on the road a while and "hot" as with all other times it revved, right?

Reading it all again, I'm not clear about the shifter position(s) immediately after it revved. IE, After the first time (when you moved the shifter to see if it had popped out of gear), did you ever happen to see what happened if you worked the clutch before moving the shifter and see if it would pull?? ...or feel the normal synchronizer bump-resistance when moved into neutral the first time afterwards by chance?
Did you have to stop to get it to work again? Every time?

=================

If it always revved when in 4th gear:
Did 4th ever act up going in like 1st or do anything else odd?
What condition was the pilot bearing in?
How much movement is there in the output shaft (both ways)?
Dana got me thinking about 4th and its synchronizer keys (aka strut wings/lock dogs) being on the opposite end of a sloppy output shaft.... Anything that would not raise Hades when it 'turned loose'/revved.

(But I'm still rooting for hydraulics ;-)

[Bitsyncmaster]

Was this during the time(s) previously mentioned? ...Your D had been on the road a while and "hot" as with all other times it revved, right?

Reading it all again, I'm not clear about the shifter position(s) immediately after it revved. IE, After the first time (when you moved the shifter to see if it had popped out of gear), did you ever happen to see what happened if you worked the clutch before moving the shifter and see if it would pull?? ...or feel the normal synchronizer bump-resistance when moved into neutral the first time afterwards by chance?
Did you have to stop to get it to work again? Every time?

=================

If it always revved when in 4th gear:
Did 4th ever act up going in like 1st or do anything else odd?
What condition was the pilot bearing in?
How much movement is there in the output shaft (both ways)?
Dana got me thinking about 4th and its synchronizer keys (aka strut wings/lock dogs) being on the opposite end of a sloppy output shaft.... Anything that would not raise Hades when it 'turned loose'/revved.

(But I'm still rooting for hydraulics ;-)

It was always like the transmission just shifted into neutral. Engine RPM could go up or down without car speed changing. I'm pretty sure I tired down shifting to 4th before coming to a stop and still had no connection from engine to transmission. I think it would only go back to normal after I stopped the car for a few minuets. I'm pretty sure I also had the problem with 4th gear which I tested after the first and many problems in 5th gear. No partial slipping or noises at all, was always like the clutch let go. I never gave it heavy acceleration hopping I could drive it back home but the problem never went away.

I wish I would have thought to check that the clutch pedal still had some slop at the top (no clutch pressure). It does have that slop now and when I've checked it before but that was always when the car was not driven for a while.

Throwout bearing looks and feels good. Also Looks like engine rear main seal not leaking. Also transmission seal not leaking. I think the oil I see is from engine case seals.

I can't really select all gears with the transmission out of the car since I can't push or pull (gate cable) the shift arm to known positions. But rotating the input shaft both ways the drive axle shafts move with no play both forward and reverse.

The end of the input shaft has about 0.10" movement total pushed and pulled left and right.

On a side note, I did replace the master clutch seal one or two years ago because I was getting a little leak inside the car. I'm not sure if I had done a long ride after I did that work or not.

If I missed any other questions from all responses please ask again. Thanks for all the help everybody.

[David T]

If it "goes back to normal after a few minutes", that could be a bad or maladjusted clutch master cylinder. Somehow it is not releasing the pressure in the slave cylinder. No way that is the transmission, they don't fail and all of a sudden work again. Or maybe the fluid is boiling and causing the problem. I would rebuild/replace the master and slave, if you have the plastic hose replace it with the S/S braided hose and refill with Castrol DOT 4. As long as you have removed the clutch it should now be replaced.

[Bitsyncmaster]

Have not done much with this project lately. I did a quick clean up of the flywheel friction surface by sanding it on a surface block with 120 grit silicon carbide sand paper. Note a surface block is a granite block with a flatness of 0.0001" inch. That showed the machine head when the flywheel was machined was a little tilted since my sanding removed the machine marks on the inside circumference and not on the outside. Still nothing that would cause the failure.

If you have not seen on DAP's web site the claim that:

"Beware of the newer Valeo clutch kit: The pressure plate takes 1450.00 PSI pressure to engage and the original took 1123.00PSI to engage."

https://www.deloreanautoparts.com/delorean-parts/clutch-transmission.html

That makes me think that maybe I should not increase my step machined onto the flywheel from the current 0.016" to 0.030".

Right now I'm thinking I just may replace my master clutch cylinder since I have not found any evidence of what caused my problem with clutch mechanics. I do need a new boot on the slave since it's torn (about 10 years old). The fork looks in great shape. The engine and transmission main seals look not to be leaking any. I assume they were already changed when the clutch was reworked 20 years ago.

I wanted to set up a test of the pressure plate but after looking at load cells I can't justify spending $500 for a load cell unit which would fit between my 20 ton press and the pressure plate fingers.

[Bitsyncmaster]

So how does the master cylinder work? The slave would be pushed back by the pressure plate. So does the master work like a check valve and return to it's resting position and fill fully with fluid ready to provide the full stroke of the master?

Why would an adjustable pedal set not to return all the way back cause problems?

[DMC-81]

Have not done much with this project lately. I did a quick clean up of the flywheel friction surface by sanding it on a surface block with 120 grit silicon carbide sand paper. Note a surface block is a granite block with a flatness of 0.0001" inch. That showed the machine head when the flywheel was machined was a little tilted since my sanding removed the machine marks on the inside circumference and not on the outside. Still nothing that would cause the failure.

If you have not seen on DAP's web site the claim that:

"Beware of the newer Valeo clutch kit: The pressure plate takes 1450.00 PSI pressure to engage and the original took 1123.00PSI to engage."

https://www.deloreanautoparts.com/delorean-parts/clutch-transmission.html

That makes me think that maybe I should not increase my step machined onto the flywheel from the current 0.016" to 0.030".

Right now I'm thinking I just may replace my master clutch cylinder since I have not found any evidence of what caused my problem with clutch mechanics. I do need a new boot on the slave since it's torn (about 10 years old). The fork looks in great shape. The engine and transmission main seals look not to be leaking any. I assume they were already changed when the clutch was reworked 20 years ago.

I wanted to set up a test of the pressure plate but after looking at load cells I can't justify spending $500 for a load cell unit which would fit between my 20 ton press and the pressure plate fingers.

FYI, I have a new Valeo clutch kit with a new DMC master, slave, and SS braided line. I didn't notice an increased pedal effort after installation. I suppose more pressure on the pressure plate will help prevent clutch slipping.

I wonder if there were problems with the older Valeo versions not lasting long enough due to the lower pressure?

[Ron]

I think it would only go back to normal after I stopped the car for a few minuets. I'm pretty sure I also had the problem with 4th gear which I tested after the first and many problems in 5th gear. No partial slipping or noises at all, was always like the clutch let go.
That helps.

I agree with David about the transmission not coming and going like that. Since the trans is quiet, tight (and 4th is not the only gear it happens in), but, it would not pull immediately after stopping then pull again in a few minutes, I'd say it is a clutch/hydraulic problem. If you bled it during the time period that it usually required to wait (?) and it wouldn't pull right then, then I'd suspect the hydraulics a lot less. Otherwise, since none of it makes any odd noises etc., I still rooting for hydraulics (adjusted too tight #1).

Replacing (not rebuilding) the MC is what I would do too. Then ensure everything from it to the slave is ok. You might want to measure/mark where the fork arm sits when you manually hold it against the throwout bearing before installing the slave (for reference later).
:wrenchin:
.

[Bitsyncmaster]

I'm guessing John tested the pressure plates by putting a pressure gauge on his hydraulic press since he is stating PSI and not pounds. I still wondering what the difference with force would make increasing the step cut 10, 20 or 30 thousands. I've looked on the internet and see clamping force of 1300 to 2100 lbs on a few clutch systems.

The clamping pressure you would measure the force to seat the pressure plate onto the flywheel.

The force to release the clutch would be the force on the fingers to release. They would differ depending on the mechanical design of the fingers.

[Ron]

So how does the master cylinder work? The slave would be pushed back by the pressure plate. So does the master work like a check valve and return to it's resting position and fill fully with fluid ready to provide the full stroke of the master?

Why would an adjustable pedal set not to return all the way back cause problems?I'm guessing it relates to what I said before (post 50). Unlike most brake MCs, a clutch MC has one port in and one port out. If the rod is too tight before attempting to bleed, it would probably never would -- The piston can't return past the intake/fill port to allow the bore to be refilled... If adjusted too tight after bleeding, after the first stroke, the piston piston can't return past the intake/fill port to allow fluid to return to the reservoir (extra due to: fingers compensating for clutch wear, heat expansion, line damage, ...?) Again, everything would have to be just right (wrong;-), but there is nothing else left I can think of anyway (nothing but heat changes as you are driving down the freeway and stay in one gear...).

[David T]

When you release the clutch pedal the master cylinder, when properly adjusted, allows any pressure in the system to bleed back to the reservoir. If it malfunctions or is not properly adjusted, and the master cylinder won't allow pressure to release, as the brake fluid gets hot and expands it can make the clutch slave disengage. Same problem if the brake fluid is contaminated with water and turns to steam and increasing the pressure. Same cure, rebuild/replace the clutch master and then flush and bleed the clutch hydraulics. Good practice, if you do something to one cylinder you should do the other. While the clutch is out it is easy enough to do the slave cylinder. I am guessing, since you have an adjustable link, the pedal is maladjusted and not allowing the pressure to release back to the reservoir. Either get rid of the adjustable link or try to get it properly adjusted. The adjustable link was an ill attempt to overcome the plastic hose syndrome. The fix for plastic hose syndrome is to replace it with the braided S/S hose.

[Ron]

https://www.deloreanautoparts.com/delorean-parts/clutch-transmission.html

That makes me think that maybe I should not increase my step machined onto the flywheel from the current 0.016" to 0.030". That says to remove the step for the thicker disk... I don't know, but if .016" makes a significant difference there, ~doubling yours (.015 to .030) don't sound right?? (Unless it is for a HO racing setup, the clutch-plate set should be made for the factory grind in any case, imho.)

Just saw this:
"18 - Remove the flywheel attaching bolts and the flywheel. CAUTION: Very Heavy! Have a machine shop resurface the flywheel, be sure they are aware that a .020 in step is machined into the flywheel and must be maintained. (http://support.delorean.com/kb/a109/manual-transmission-clutch-replacement-new.aspx)"

[DMC5180]

That’s says .020 step. I can’t imagine .004 less causing a significant issue.




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[David T]

That step and all of the other dimensions are critical because there is no mechanical adjustment that can allow for any variance. If the step is not right, if the friction disc is too thick, if anything is not just right, the clutch will not work correctly and you can't adjust it. The clutch hydraulics is the only thing meant to compensate for wear and even that is very small.

[Ron]

That’s says .020 step. I can’t imagine .004 less causing a significant issue.Me either.
.004 sounds more like a few teenager burnouts

fwiw, I only posted the link because I didn't see an OEM spec in the thread...

[Bitsyncmaster]

Me either.
.004 sounds more like a few teenager burnouts

fwiw, I only posted the link because I didn't see an OEM spec in the thread...

I'm glad you found that spec. It's the only one that is documented.

I ordered a hydraulic force gauge (used on Ebay) for $147 shipped. It's just a low profile cylinder/piston with a gauge calibrated to read in pounds (0 to 10,000 lbs.). You just place it between the press and unit to test and read the result. Not that I really need this but I love to test things. Anyway I can compare the centerforce static clamping force with the new pressure plate. Will also compare the force required to release the clutch.

Would probably be a useful tool for the V8 guys testing their clutch components.

[DMC5180]

I'm glad you found that spec. It's the only one that is documented.

I ordered a hydraulic force gauge (used on Ebay) for $147 shipped. It's just a low profile cylinder/piston with a gauge calibrated to read in pounds (0 to 10,000 lbs.). You just place it between the press and unit to test and read the result. Not that I really need this but I love to test things. Anyway I can compare the centerforce static clamping force with the new pressure plate. Will also compare the force required to release the clutch.

Would probably be a useful tool for the V8 guys testing their clutch components.

So what you are saying is, once you do your test, it will be for sale. :wink:


Back to your original issue. You stated that it felt like the transmission went into to neutral. Did it stay like that all the way to a rolling stop, or did you by nature push on the clutch at some point? I've been trying to run through my head other possible scenarios. I can only think of 2 extremely remote possibilities. 1. partially stripped teeth on the input shaft coupler. 2. partially stripped outer axle stub shaft to hub assembly. The effect of the second one would disconnect or decouple one drive wheel, having an open differential will cause the disconnected half shaft to speed freely and the other wheel will see no power to it. It would be as if you shifted into neutral. Dave Swingle posted a photo several years back of car they got in the shop that suffered this bizarre failure, the teeth on the hub flanges were rusted and wore off.

I had something like that happen on my 85 Audi Coupe. I was headed to work one early morning many years and all of sudden I lost power to the wheels with the car in gear. I pulled over to stop and investigate. With the car stopped and in gear idling, I get a look under the car and the Right half shaft was turning will the car sat motionless. Something let go in the outer CV joint assembly.

[Bitsyncmaster]

So what you are saying is, once you do your test, it will be for sale. :wink:


Back to your original issue. You stated that it felt like the transmission went into to neutral. Did it stay like that all the way to a rolling stop, or did you by nature push on the clutch at some point? I've been trying to run through my head other possible scenarios. I can only think of 2 extremely remote possibilities. 1. partially stripped teeth on the input shaft coupler. 2. partially stripped outer axle stub shaft to hub assembly. The effect of the second one would disconnect or decouple one drive wheel, having an open differential will cause the disconnected half shaft to speed freely and the other wheel will see no power to it. It would be as if you shifted into neutral. Dave Swingle posted a photo several years back of car they got in the shop that suffered this bizarre failure, the teeth on the hub flanges were rusted and wore off.

I had something like that happen on my 85 Audi Coupe. I was headed to work one early morning many years and all of sudden I lost power to the wheels with the car in gear. I pulled over to stop and investigate. With the car stopped and in gear idling, I get a look under the car and the Right half shaft was turning will the car sat motionless. Something let go in the outer CV joint assembly.

Yes I would probably sell the force gauge after I play with it. I guess you could use it also to measure springs but your would need a safe fixture to to do that testing.

I tried to shift into other gears but it never got any power to the wheels. After a short stop every worked fine for a mile or two going through all the gears normal and it all happening again. I really don't want to open the transmission if I don't have to since there are no leaks.

[DMC5180]

All gears or no gears would indicate a single point failure. Either one of the two I mentioned fit that definition.


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[Ron]

I still can't imagine anything but the clutch system that would disengage and then engage that many times w/o raising hell.
Anything else either has teeth, where at least one toothed part has to move off center for it to disengage, which you would hear and probably feel, OR, are permanent/solid, and once 'broke', would never look or act right again.

[DMC5180]

Yup, hence the reason I said, “extremely remote possibility “

Just spit balling ideas. I’m still with you on the clutch master piston seal covering the reservoir port. Either that or there is some weird obstruction blocking the vented reservoir cap the not allowing the system to breath.


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[Bitsyncmaster]

Yup, hence the reason I said, “extremely remote possibility “

Just spit balling ideas. I’m still with you on the clutch master piston seal covering the reservoir port. Either that or there is some weird obstruction blocking the vented reservoir cap the not allowing the system to breath.


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I welcome all ideas. I was also thinking if a gear or coupling was worn then I would have heard or felt noise and it would not return to normal. I did replace the seals in my master but don't remember if I had made a long trip after that. I also don't think I ever checked the pedal play after driving the car but would not think that would change. I'm planning on getting a new master after I get the car back together.

[Ron]

Yup, hence the reason I said, “extremely remote possibility “

Just spit balling ideas. I’m still with you on the clutch master piston seal covering the reservoir port. Either that or there is some weird obstruction blocking the vented reservoir cap the not allowing the system to breath.
I was with you brother. :rock_on:


Dave, when you bled the slave, assuming it was right after coming to a stop and no one was pressing the pedal, did the fluid shoot out, or ??

[Bitsyncmaster]

I was with you brother. :rock_on:


Dave, when you bled the slave, assuming it was right after coming to a stop and no one was pressing the pedal, did the fluid shoot out, or ??

It was still a little dark but I think it just dripped a little when I opened the "bleeder". I have the Hervey extended bleeder so that could be done on the road.

By the way here is a photo of my engine hold bar. So far this has worked out good because it keeps the engine right where it should be and no blocks under the car to get in the way. Also shown is how high it's jacked up. This did let me slide the transmission out the back.

[DMC-Ron]

Dave,
When this happened, was there a time when you had no power to the wheels in 1st, 2nd, or 3rd gear? Or did they immediately work after coasting to a stop?

I apologize if you already addressed this but wanted to clarify.

Ron

[Bitsyncmaster]

Dave,
When this happened, was there a time when you had no power to the wheels in 1st, 2nd, or 3rd gear? Or did they immediately work after coasting to a stop?

I apologize if you already addressed this but wanted to clarify.

Ron

From what I remember the first time I did not have to stop since I thought it just slipped out of gear so I continued. I think the next time I tried shifting but don't remember if I had to stop to get power again or not on the second time. But I do remember having to stop to get any gear to engage power for many times. I never really tested if a long time stop would have fixed it.

[Nicholas R]

This conversation has gotten really into the weeds regarding step height...

For what it's worth, when I made my first flywheel for my engine swap, I used a step height of .040" using a SpecialT re-surfaced kevlar disc, and a SpecialT "upgraded" Valeo pressure plate. I did it to ensure engagement, and potentially get a little bit more clamping, and more use from the clutch. It worked great, and never had any issues engaging or disengaging. Everything else about the clutch system was stock, with the exception of the SS braided clutch line.

Those components are still in my car now 6 years later, though admittedly I'm planning to switch soon to a new flywheel, clutch, and pressure plate design that doesn't use a step.

Regardless, my point is that I don't think you need to sweat a couple thousandths of an inch.

[DMC-Ron]

From what I remember the first time I did not have to stop since I thought it just slipped out of gear so I continued. I think the next time I tried shifting but don't remember if I had to stop to get power again or not on the second time. But I do remember having to stop to get any gear to engage power for many times. I never really tested if a long time stop would have fixed it.

OK. I was off on a tangent wondering if the shift linkage could be involved.
Ron

[Bitsyncmaster]

I assume it's normal if you just turn one of the axle flanges the other one turns reverse and no input shaft turning. Then if you hold one flange and turn the other the input shaft then turns (in gear).

There is a little rust on the fork pivot ball and socket. The spring clip is in the way for cleaning the socket. Spring clip is riveted on, can I remove the clip to clean the area and then bolt the clip back on? Maybe I can clean the socket with a small Dremal brush without removing the spring clip.

I can feel a little wear on the "pipe" where the throwout bearing slides. I guess this is normal and does not warrant replacing that "pipe".

[Nicholas R]

I assume it's normal if you just turn one of the axle flanges the other one turns reverse and no input shaft turning. Then if you hold one flange and turn the other the input shaft then turns (in gear).

There is a little rust on the fork pivot ball and socket. The spring clip is in the way for cleaning the socket. Spring clip is riveted on, can I remove the clip to clean the area and then bolt the clip back on? Maybe I can clean the socket with a small Dremal brush without removing the spring clip.

I can feel a little wear on the "pipe" where the throwout bearing slides. I guess this is normal and does not warrant replacing that "pipe".

Just drill out the rivet, clean it, and then pop-rivet it back into place. It's not worth trying to put a bolt here and risking it coming loose. I did this to mine, except my clip had one of the blades broken off, so I made a replacement clip out of steel sheet.
57720

[Bitsyncmaster]

I was cleaning things up getting ready to force test when I get my force gauge and noticed a little blue mark on the old pressure plate. I don't see any reason for this overheating in that one spot unless that is the first point of contact.

I still see the machine marks evenly all around that pressure plate.

[Ron]

After seeing this (and cataract surgery yesterday:-) I took another look at all of the pics. Not only does it appear that some of the weights were not moving as noted in post 54, pic 2, the parts are not on the same axis. IE, the circle(s) formed by the fingers, weights, and retainer/spring are not concentric. My guess is that you are right and your test will confirm that the area with the blue spot touches the flywheel first. And that it is doing this WAY before tolerances allowed for it to mate evenly, making the area over heat. There are a lot of hot spots and odd looking patterns on all of the mating surfaces. The fingers show signs of excessive throwout bearing preload (esp. when compared to the amount of wear on the disk). Which would mean the bearing was always turning. I hate to say it, but I'd get the flywheel resurfaced and replace the entire clutch set. (Hopefully the vendor will see the relatively small amount of wear on the disk and work with you...)

[Bitsyncmaster]

I already have the new clutch kit and I ordered Hervey's stainless lined master and slave (hope that is going to arrive).

Yes the weights are not all centered and I'm going to do a little more inspection there even though that pressure plate is just going to be trashed.

[Bitsyncmaster]

I bolted down the centerforce pressure plate on the flywheel with the new clutch disk. I did not see any possible way the weights could jam things. So I removed the weights so I could measure the angle of the fingers on the pressure plate and the angle is only 1.3 degrees from 90 (flat with the clutch). So it's such bull shit that the centerforce helps add force with dynamic forces.

The weights were not concentric so they probably upset the balance anyway. I see the flywheel was balanced but don't see the pressure plate had any balance drilled holes.

I'm machining a test "throwout bearing" so I can measure force required to release the clutch.

[Bitsyncmaster]

Here is my test "throwout bearing". This should stay centered on the fingers. Would have been better to make it out of steel but wanted to machine it faster. This is 2024 aluminum.

[Bitsyncmaster]

Got my force gauge. I'm impressed with the quality. It has a calibration sticker of 8-29-2013. I set it on my press and brought it up to half scale (5000 lbs.). Let off the press and the needle went to zero.

I set the old centerforce pressure plate with the new disk on the flywheel. Put the screws in less two turns from bottom. I added force until all 6 mount points contacted the flywheel and the force was 2100 lbs.

I will test that holding force on the new pressure plate and also test the release force on each. For that I plan to just apply force to the fingers until I can turn the disk with the alignment tool.

I was thinking a 10,000 lbs full scale may not give me good resolution but it takes very little press movement to add 100 lbs. so don't think you can get much better than 100 lb resolution. So probably a 5000 lb full scale would be the best.

[Ron]

Some people get to play with all of the good toys..

[Bitsyncmaster]

My new method of testing the clamping force on the disk it to just sit the pressure plate on the three guide pins of the flywheel. Then add force in 50 pound increments until I can’t slide a 0.004” shim stock feeler gauge under all 6 bolt contact points. This gives me more repeatable (accuracy) to my testing. Note there are three legs of the pressure plate. Each location has a guide pin and two bolt holes to mount to the flywheel.

Also to note, the pressure plates are balanced. Each of those three legs has a hole for a balance weight. The Centerforce plate has one weight and the new Valeo plate has two weights.

1750 lbs. Clamp force for Centerforce
1600 lbs. Clamp force for Valeo

The release test you just apply a little force on the side of the disk with a pencil until it moves.

Centerforce peak 250 lbs. No drop in force and disk goes loose, distance to release is 0.214”
Valeo peak 400 lbs. then drops to 350 lbs. and disk goes loose, distance to release is 0.204”

[Bitsyncmaster]

I found a problem with my release test on the Valeo pressure plate. I noticed my test throwout bearing has signs of the fingers hitting it where I made a center dia. to keep it centered. The fingers are a little longer which I had notaced before but the fingers sit at quite a bit of angle even when the pressure plate is bolted down. So what happened was the fingers bound up on my test throwout bearing which threw the reading off.

The new reading after machining that dia. down.

Valeo peak 300 lbs. No drop in force and disk goes loose, distance to release is 0.204”

So not much difference in any clutch components. I got the new stainless sleeved master and slave from John and he suggested maybe the slave was sticky. The old slave does have a tear in the boot.

[Ron]

If you are not already installing :biggrin:... I wonder what the bearing travel would be for each after bolting them to the flywheel?

[Bitsyncmaster]

If you are not already installing :biggrin:... I wonder what the bearing travel would be for each after bolting them to the flywheel?

I will give it a test. It seems the force is pretty constant through the travel so I can stop when force increases. I was surprised how low the force was to release the clutch. I see Centerforce has a new claim that they use ball bearing pivots on the fork arms to reduce clutch forces.

I am ready to start assembly. I did pull the transmission with the slave attached but think I will install the slave after installation just so it with the long bleeder hose is not going to get hung up. I also plan to use wheel bearing grease for the fork and throwout bearing surfaces (where it rides on the tube). I need to buy some new blue locktite since my old bottle of it must be 20 years old now. I think I will also replace the master cylinder first so I can get those cores returned to John.

[Bitsyncmaster]

I tested the Valeo pressure plate again since that was still bolted to the flywheel. This time I put a little grease on my test throwout bearing so it could center on the fingers as I applied force. The Valeo fingers are still angled up so as I press them down that center hole gets smaller until the fingers are parallel with flywheel.

The force is pretty consistent at 250 lbs until the clutch disk goes free. Note my force gauge has a scale of 0 to 10,000 lbs. so reading these low values I'm splitting hairs on the gauge. This distance reads 0.227"

Then after the disk released, the force dropped to about 200 lbs. and continued to drop to 100 lbs. until I stopped at a distance of 0.391" total. I did not want to test it to far fearing doing some permanent damage.

The numbers stamped on the Valeo pressure plate:
185873 235 CP 5500 MADE BY VALEO MC3 26/09/16 03 23 00

Also to note the fork:
Distance from fulcrum to slave is 4.28" and distance from fulcrum to throwout bearing is 3.34"

[Bitsyncmaster]

Temporarily installed the new slave and noticed the pipe was touching the transmission. So added a little vacuum tube to isolate that. By the way my old slave did have a little sticking way down with the piston all the way in but it's nothing the 100 plus lbs. of return force would not take care off.

Also a photo of my force gauge. I would guess for this work a 2 ton (4000 lbs) gauge would have been better. But this one is so well built I trust it gave me pretty good accuracy.

[DMC-81]

Nice testing Dave! :thumbup:

[Bitsyncmaster]

Got the master out. The reservoir hose should be replaced. One of the hose clamps was even rusted through so it just fell off. Was thinking of replacing the master mounting screws with "Allen" head type. The top screw is the pain to remove because the arm on the clutch linkage is right over the screw.

[Bitsyncmaster]

My old master cylinder has what looks like a white salt filling the boot where the clevis goes. This end of the cylinder is inside the car so I guess it's from the DOT4 fluid. Has anyone seen this before? Don't know what that would do to my clutch system.

[David T]

Got to be some form of corrosion. Definitely not good. Probably means the seals are leaking.

[Bitsyncmaster]

Was installing the new master cylinder. The new boot has to be pulled off the master end to fit through the hole in the firewall. I did buy Allen head bolts to replace the Phillips head mount bolts (10 mm 1.5 30 mm long). I was cleaning the reservoir and notice the cap has a small air vent. Modern cars have a bellows on the cap so air is not vented into the reservoir. Maybe a clutch flush more often is necessary.

I was also going to install the flywheel and pressure plate but wanted to chase the threads since you should clean out the old locktite. The flywheel bolts are 10mm 1.0 thread which is a rare tap size so I have to run down to ACE to buy one.

[David T]

All owners should be flushing and replacing their brake fluid at least every other year. If you have a 5-speed you must also do the clutch fluid at the same time. It is a WHOLE lot cheaper and easier than replacing the parts when they go bad because the fluid rotted things inside. IMHO Locktite is not necessary on the bolts holding the pressure plate to the flywheel. It IS necessary on the bolts that hold the flywheel to the crankshaft. Typically I do not use a tap to "clean" threads in preparation for Locktite. Locktite has a primer if you think you need it. Some compressed air in the bolt holes to blow out any dirt should be sufficient. You are correct about the air, because the fluid is in contact with the air it allows moisture and condensation to eventually contaminate the brake fluid. By driving the car and heating up the brake fluid the moisture gets driven out. Because our cars aren't used alot the moisture builds up and turns the fluid acidic. It attacks the metal surfaces and then the seals leak because of the rough surfaces. By replacing the fluid before it goes bad you prevent the damage.

[DMC-81]

I used blue locktite on the pressure plate to flywheel bolts, and I always clean the old locktite or any sealing material out of any threads with a tap, then compressed air. The advantage is a cleaner surface for the Locktite to serve it's purpose and it allows a more accurate torque reading.

[Bitsyncmaster]

All owners should be flushing and replacing their brake fluid at least every other year. If you have a 5-speed you must also do the clutch fluid at the same time. It is a WHOLE lot cheaper and easier than replacing the parts when they go bad because the fluid rotted things inside.

All the more reason to get stainless sleeved master and slave.

[Ron]

...
I always clean the old locktite or any sealing material out of any threads with a tap, then compressed air. The advantage is a cleaner surface for the Locktite to serve it's purpose and it allows a more accurate torque reading.+1 Loctite or not, if it's torqued, a tap is going in there so I can see the threads -- I don't like $urprises!

[David T]

Torque values are all assumed "dry" unless otherwise mentioned. Using Locktite interferes with the accuracy of the torque making it higher than it should be. The torque alone is supposed to be more than enough for most locations. The pressure plate bolts were not originally locktited in.

[DMC-81]

Torque values are all assumed "dry" unless otherwise mentioned. Using Locktite interferes with the accuracy of the torque making it higher than it should be.

Correct. What I do is cross reference the Workshop Manual torque values with an industry standard chart which takes dry/lubricated/plated situations, bolt strength & size, and materials when using anything other than dry.


The torque alone is supposed to be more than enough for most locations. The pressure plate bolts were not originally locktited in.

Well, I wouldn't consider a high speed rotating assembly that has to endure repeated high pressures to be included in "most locations". I'm sure that if we were mass assembling factory new parts, we would omit thread locker, but we are typically reassembling used parts especially the 9mm pressure plate bolts) where there is a loss of plating on the bolt, surface rust, dirt, etc. that can interfere with a tight fastener. Plus, DMC recommended thread locker in that location, even when I replaced the old 9mm bolts. I consider it cheap insurance.

[Bitsyncmaster]

I was also going to install the flywheel and pressure plate but wanted to chase the threads since you should clean out the old locktite. The flywheel bolts are 10mm 1.0 thread which is a rare tap size so I have to run down to ACE to buy one.

The flywheel bolts are 9mm 1.0 thread. So if I want to chase those threads I need to order the tap over the internet.

[DMC-81]

The flywheel bolts are 9mm 1.0 thread. So if I want to chase those threads I need to order the tap over the internet.

Dave, that's right. I remember one of the 2 being a rare size. It was the 6 M8x 25mm pressure plate bolts ( 102593 ) I replaced.

57828

[Ron]

The flywheel bolts are 9mm 1.0 thread. So if I want to chase those threads I need to order the tap over the internet.I wouldn't let that hold up the job for days...maybe go to Ace/? and get a brass/bronze wire bore brush.

[Bitsyncmaster]

I wouldn't let that hold up the job for days...maybe go to Ace/? and get a brass/bronze wire bore brush.

I have not decided if I will wait. I did finish installing the master and need to do some odds and ends on the transmission (one mount bolt was tight removing so need to chase those threads). I bought two long bolts and will cut the ends off to use as a guide when installing the transmission. I also noted the drivers side rear cam plate looks like it's leaking some oil so may pull that off and reseal it (I guess it's just a cover plate). Those things are easy to get to with the transmission remove and car up on blocks.

I'm still concerned I did not find what caused the problem. I plan to do a drive half the distance where it acted up and then return home so if it still has the problem I won't need a tow.

[Bitsyncmaster]

Turns out that tight bolt on the transmission is because someone tightened the back cover on the transmission before all the bolts were installed. So the bolt hole is rubbing on the bolt.

[Bitsyncmaster]

I forgot to mention that my problem was defiantly not caused by not enough clutch pedal travel. It's easy to see when you pull the pin off your clevis to the master. Mine has about 3/4" of extra travel.

[Bitsyncmaster]

I removed that cam cover plate that was leaking oil. Looks like they used red locktite on the two 6 mm bolts holding the cover on so I could not tell if the bolts were actually tightly bolted down. I could see where the oil was leaking on the cover plate. I chased the threads holes and I think the holes are open to oil since the tap went in about 3/4" so I will use a sealer on the bolt threads.

I think you would have to have the transmission removed or the head pulled to access that cover plate.

Maybe that is the only cause of the oil leaking on the rear of the engine.

[Bitsyncmaster]

I finished installing the cam cover. Made a new gasket and used Permatex sealer.

I installed the slave, fork and throwout bearing. By the way the new throwout bearing looks constructed better than the one I removed. Only marking on the new bearing was "Valeo".

I noticed a little bend in the rod that connects the slave push rod to the fork. Don't think it enough to replace it. But what would have caused that. My guess is only if the clutch had to much throw and it bottomed out. Not sure if I ever push the clutch peddle to the floor.

Every thing is ready to go back in after I get my 9mm tap to chase the flywheel bolts. I do need to rebuild one axle which can keep me busy for another day or two.

[Bitsyncmaster]

I should have checked my mail box yesterday. My taps were waiting for me. Amazed I ordered them on Saturday and they arrived on Monday. However the taps were a little to large for me to chase the threads. OD on the tap was 0.0095" over the bolt OD and they started cutting metal so I decided not to chase the treads.

Got the flywheel, clutch plate and pressure plate mounted, blue locktite and torqued to spec. Now the heavy part of lifting the transmission and bolting in place.

[Bitsyncmaster]

It took 2.5 hours to push the transmission back under the car and get it back sitting on the jack. It just took a lot of wood blocks rocking the transmission back and forth to get it up high enough to slid it onto the jack. I need to center on the jack and then it's ready to push back onto the engine.

[Bitsyncmaster]

It took about 1.5 hours to get the transmission bolted back onto the engine. I could not find the torque spec for those 4 10mm bolts so I used 45 ft/lb. Those bolts are 10.9 rated so the torque may be a little more than 45 ft/lbs.

Note to others doing the transmission is you need to move the shift lever so you can push it in to clear the water pipes as you lift the transmission.

[Bitsyncmaster]

I forgot to mention that when I was installing the transmission, I had a problem pulling the last 3/8" inch up tight to the engine. What I did was install the four bolts (to the engine) finger tight and then "jiggle" the transmission just a little. I guess with the bolts installed it was enough to work the two guide pins into their holes.

[David T]

The main purpose of the guide pins is so you approach at the right angle. That last little bit is when you enter the pilot bearing and then the dowel pins. It also helps to put the transmission into gear so you can turn the input shaft to align the splines. The pilot tool centers the clutch plate but you must still align the splines into it.

[Bitsyncmaster]

Went to install the brackets onto the rear of the transmission. The pivot bracket arm was very tight moving it so I took it apart. Looks like it was just the silver anti-seize grease that was causing the binding. I guess it's not a good idea to use that type of grease on a bronze bearing bolt.

Now how in the heck do those brackets install? The pivot bracket is easy to see where it mounts but the shift cable brackets don't make sense. I will try to find a drawing that shows the correct install.

[DMC-81]

Went to install the brackets onto the rear of the transmission. The pivot bracket arm was very tight moving it so I took it apart. Looks like it was just the silver anti-seize grease that was causing the binding. I guess it's not a good idea to use that type of grease on a bronze bearing bolt.

Now how in the heck do those brackets install? The pivot bracket is easy to see where it mounts but the shift cable brackets don't make sense. I will try to find a drawing that shows the correct install.


Dave,

Here are a couple pictures if they help any.

http://dmctalk.org/attachment.php?attachmentid=47654&d=1480988726

http://dmctalk.org/attachment.php?attachmentid=47656&d=1480989129

I used Rob Grady's recommended 50/50 mixture of moly grease and anti-seize on some transmission parts ( pivot ball, fork, TO bearing to input shaft tube, input shaft splines, Bellcrank ). Perhaps you can use it on the pivot bracket arm.
http://dmctalk.org/attachment.php?attachmentid=49957&d=1490829652

[Bitsyncmaster]

Thanks. I did get all the brackets bolted down. It was the one that bolts with the long bolt that threw me.

Now for adjusting the shift cable. I guess I'm just going to have to hook it up and play with the adjustment till I get reverse and fifth gear. The push rod should not have change.

[DMC-81]

Thanks. I did get all the brackets bolted down. It was the one that bolts with the long bolt that threw me.

Now for adjusting the shift cable. I guess I'm just going to have to hook it up and play with the adjustment till I get reverse and fifth gear. The push rod should not have change.

Good to hear. Yes, that's a good approach.

[Bitsyncmaster]

Got the transmission all bolted up. Think I stripped a starter bolt:shock:. Will need to pull the starter later and helicoil it. Need to put the parking brake cable back on, fill and bleed the clutch and put the axles back on (one needs a rebuild first).

[Bitsyncmaster]

I did a vacuum bleed on my clutch this morning. That just applies vacuum through a bottle to the slave bleeder until I got a few ounces of fluid in the bottle. Not sure how well it worked. Will test when I have the engine running.

When I press the clutch pedal by hand, it requires pressure and then about half way down the pressure required drops and the pedal moves easily to the floor. Not sure if this is normal because I've never really pressed it by hand before.

[Bitsyncmaster]

Got the engine started and the clutch seems to work (no drive axles) so I can run through the gears......except reverse. So looks like I need to adjust the cable. Anyone know if it needs to be longer or shorter? I will find out if not.

Clutch seems to take hold close to the floor so I probably need to bleed it some more.

After the adjustment I only have to install the air deflectors and drive axles to finish the job. I should rebuild the one axle first. The other axle is new and I have the boots and grease for the old one.

[Bitsyncmaster]

So if you don't get reverse you need to shorten (turn the clevis clock wise looking at the end) the cable.

I turned it two turns but if your just sometimes having problems use a half turn. When you remove the cable from the brackets you loose the correct position and will need to make fine adjustment via the clevis end.

[DMC5180]

You shouldn’t need to adjust the clevis if you didn’t disturb it’s original position on the inner member. You adjust the outer jacket via the Jam nuts in the bracket.

Take a look at Dana’s transmission rebuild thread I believe he made a photo that shows the directional adjustments for desired effects.


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[Bitsyncmaster]

Started rebuilding my old axle. Boy if I knew how messy this job was I would have sent it off for rebuild. It looks like someone tried to do pull ups on the axle when one end was hanging.:8ball: The cup is shaped like a triangle. Guess I have to hammer it back round on a pipe to form it.

[DMC-81]

Started rebuilding my old axle. Boy if I knew how messy this job was I would have sent it off for rebuild. It looks like someone tried to do pull ups on the axle when one end was hanging.:8ball: The cup is shaped like a triangle. Guess I have to hammer it back round on a pipe to form it.

Lol! Yes, I had to do that exact thing on one of my flanges. I believe I used a combination of an ABS pipe and a bench vice ( with jaws softened with a wood strip) to slowly roll the flange back to normal. Otherwise, the rubber boot would not stay on properly.

[Bitsyncmaster]

Well it turned out my one new axle may have cause my problem. When I pulled the axle I noticed one boot had pulled off the flange end. Well when I was going to put the axle back in I noticed one end had pulled off the axle so the "C" clip had come off. I'm pretty sure that new axle is a little shorter than the OEM axle. So I'm guessing the shorter axle is why the "C" pulled off and hence the boot pulled off.

It just seems strange that the axle would go back in when I stopped and I could get about another mile of driving before I lost power to the wheels again.

Since I found no problem with the clutch, I'm leaning to that short axle causing my problem. If the problem returns than it would have to be something internal to the transmission.

So anyway, if you have a boot pulling off you can check your axle length by measuring the "C" clips center to center with the following table.

Length of axle shaft = 21.11"
Distance from end of shaft to center-line of the boot clamp location =4.975"
C-clamp location dia. on shaft = 1.045"
Small boot clamp center to center = 11.19”

[DMC-81]

Well it turned out my one new axle may have cause my problem. When I pulled the axle I noticed one boot had pulled off the flange end. Well when I was going to put the axle back in I noticed one end had pulled off the axle so the "C" clip had come off. I'm pretty sure that new axle is a little shorter than the OEM axle. So I'm guessing the shorter axle is why the "C" pulled off and hence the boot pulled off.

It just seems strange that the axle would go back in when I stopped and I could get about another mile of driving before I lost power to the wheels again.

Since I found no problem with the clutch, I'm leaning to that short axle causing my problem. If the problem returns than it would have to be something internal to the transmission.

So anyway, if you have a boot pulling off you can check your axle length by measuring the "C" clips center to center with the following table.

Length of axle shaft = 21.11"
Distance from end of shaft to center-line of the boot clamp location =4.975"
C-clamp location dia. on shaft = 1.045"
Small boot clamp center to center = 11.19”

Congrats Dave! In hindsight, an internally failed drive axle would cause the disconnected failure. I'm sure you wouldn't have noticed it by looking at it from the outside.

It is a rare failure though. Where did you get the new axle? The length should be correct to the DeLorean. If not, you might have the failure again, especially if you re-used the C-clip.

I imagine that the rear suspension spread gradually (or the axle was forced outward) while driving until the axle popped out of the hub. Then, as you stopped, the axle popped back into place. Just a theory.

Anyway, I'm hoping that the vendor that you got the new axle from will make it right for you.

[Bitsyncmaster]

Congrats Dave! In hindsight, an internally failed drive axle would cause the disconnected failure. I'm sure you wouldn't have noticed it by looking at it from the outside.

It is a rare failure though. Where did you get the new axle? The length should be correct to the DeLorean. If not, you might have the failure again, especially if you re-used the C-clip.

I imagine that the rear suspension spread gradually (or the axle was forced outward) while driving until the axle popped out of the hub. Then, as you stopped, the axle popped back into place. Just a theory.

Anyway, I'm hoping that the vendor that you got the new axle from will make it right for you.

Yes vendor is correcting it. I ended up rebuilding my old axle to replace it. I'm assuming someone sent in an axle from another car which happens to be shorter. I think I read some people think the Porsche axle is the same but maybe it's the one that is shorter. I would not think the C clips take much force. They just keep both CV joints running together. Without the C clip the other joint may move to it's end and make the axle shorter.

[DMC5180]

I had an axle/joint fail like that many years ago in an 85 Audi coupe. I was driving around a slow speed curve rather aggressively when suddenly the RPM shot up it felt like the car went into neutral. I rolled to stop an side road intersection , it was at night but I happened to have light with me. I got out of the car with it still in gear, but stationary. When I looked under the car, the right axle was turning inside the outer CV joint. The boot was in good shape with no tears, it was just a freak thing.


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[DMC-81]

I had an axle/joint fail like that many years ago in an 85 Audi coupe. I was driving around a slow speed curve rather aggressively when suddenly the RPM shot up it felt like the car went into neutral. I rolled to stop an side road intersection , it was at night but I happened to have light with me. I got out of the car with it still in gear, but stationary. When I looked under the car, the right axle was turning inside the outer CV joint. The boot was in good shape with no tears, it was just a freak thing.


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Wow. I suppose a similar axle under side loading would fail when you see that it's just a relatively small clip holding things together:

http://dmctalk.org/attachment.php?attachmentid=49345&d=1488940149

I had the drive axle(s) disconnect on my first car (82 VW Rabbit) 30+ years ago, but it was caused by the mechanic not tightening/ loctiting the bolts. It was a similar symptom/ feeling, i.e. engine disconnected from transmission.

[DMC5180]

Wow. I suppose a similar axle under side loading would fail when you see that it's just a relatively small clip holding things together:

http://dmctalk.org/attachment.php?attachmentid=49345&d=1488940149

I had the drive axle(s) disconnect on my first car (82 VW Rabbit) 30+ years ago, but it was caused by the mechanic not tightening/ loctiting the bolts. It was a similar symptom/ feeling, i.e. engine disconnected from transmission.

I actually had that happen too, on the LH Inner assembly to Trans hub flange. I had pulled into convenience store parked and went inside. When came out hopping in the car I put it in reverse turning the wheels a little while while letting out the clutch. Suddenly I hear a loud clunk and steering wheel jerks out of my hand. I get out and look under the car only too see the LH axle hanging by one bolt from the transmission flange. 4 of 6 bolts were gone. I got very lucky it happened where It did. I can’t imagine what that the axle would have done flailing around under the car at 65 mph.


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[Ron]

It just seems strange that the axle would go back in when I stopped and I could get about another mile of driving before I lost power to the wheels again.
+1
...and that it didn't make a lot of noise while doing it.

[Bitsyncmaster]

Today was a warm day so I drove the D around the neighborhood. It drove fine but looks like I have a clutch slave leak somewhere. Since this was only the second drive since the new clutch, I backed it up on ramps to check the main line to the short pipe connection and it looked dry. I don't think the slave to pipe fitting is leaking either. Don't think it's the Hervey bleeder line either. Hard to see much so I guess I will pull the intake off to see what is leaking. This is a new Hervey sleeved slave so I hope it's not internal to the slave.

[DMCMW Dave]

Today was a warm day so I drove the D around the neighborhood. It drove fine but looks like I have a clutch slave leak somewhere. Since this was only the second drive since the new clutch, I backed it up on ramps to check the main line to the short pipe connection and it looked dry. I don't think the slave to pipe fitting is leaking either. Don't think it's the Hervey bleeder line either. Hard to see much so I guess I will pull the intake off to see what is leaking. This is a new Hervey sleeved slave so I hope it's not internal to the slave.

Have you lost fluid in the reservoir. or do you have to pump the pedal to get it to disengage? That will tell you if it's an internal or external leak.

The master can leak internally, externally, or at the reservoir hose (won't usually cause a problem until it's dry). The slave can only leak externally.

[Bitsyncmaster]

Have you lost fluid in the reservoir. or do you have to pump the pedal to get it to disengage? That will tell you if it's an internal or external leak.

The master can leak internally, externally, or at the reservoir hose (won't usually cause a problem until it's dry). The slave can only leak externally.

I get a dripping of fluid after I operate the clutch. That drip is off the transmission and looks like it runs down the drivers side right around the axle. Driving seemed normal with clutch operation. Yes I had to add fluid to the reservoir.

[David T]

The clutch slave cylinder will only leak when it has pressure, when you step on the clutch pedal. If it leaks it must be rebuilt or replaced. Eventually you will lose enough fluid so that when you step on the pedal it won't leak anymore because you have lost all of the fluid. At that point you can't disengage the clutch or shift. Usually if one cylinder is leaking (either the master or the slave) you rebuild both figuring if one is leaking the other will too soon. This happens because the fluid is not flushed, it gets acidic and corrodes the inner bore of the cylinder. Once the inner bore gets pitted the seal gets torn as it is moved over the pits. Once the seals get torn they leak. Bottom line, to avoid leaks you flush the brake and clutch fluid at least every other year. Once you develop a leak you rebuild the whole system. You learn it is a LOT cheaper, easier and faster to flush the fluid rather than to have to rebuild everything. If you ignore the leaky clutch cylinders and force shifts you will bend the roll pin inside the transmission. Now you have to rebuild the transmission and maybe replace the clutch. Like that old saying "An ounce of prevention is worth a pound of cure"!

[DMC-81]

The clutch slave cylinder will only leak when it has pressure, when you step on the clutch pedal. If it leaks it must be rebuilt or replaced. Eventually you will lose enough fluid so that when you step on the pedal it won't leak anymore because you have lost all of the fluid. At that point you can't disengage the clutch or shift. Usually if one cylinder is leaking (either the master or the slave) you rebuild both figuring if one is leaking the other will too soon. This happens because the fluid is not flushed, it gets acidic and corrodes the inner bore of the cylinder. Once the inner bore gets pitted the seal gets torn as it is moved over the pits. Once the seals get torn they leak. Bottom line, to avoid leaks you flush the brake and clutch fluid at least every other year. Once you develop a leak you rebuild the whole system. You learn it is a LOT cheaper, easier and faster to flush the fluid rather than to have to rebuild everything. If you ignore the leaky clutch cylinders and force shifts you will bend the roll pin inside the transmission. Now you have to rebuild the transmission and maybe replace the clutch. Like that old saying "An ounce of prevention is worth a pound of cure"!

David, Dave M said in post 153 that it was a NEW sleeved slave cylinder. That would mean a possible warranty replacement if it is leaking, rather than needing to rebuild an old neglected slave cylinder or entire system.

[David T]

If it is a new cylinder then something is wrong with it. Maybe the bleeder is not tight, the seal was damaged when installed, the pipe connection is leaking, could be a lot of things. You are correct, in this case it may not be simply a corroded inner bore and a torn seal. The OP must carefully inspect the cylinder and see where it is leaking from. No leakage can be tolerated no matter where it comes from.

[Bitsyncmaster]

Well I pulled the slave. The boot was pushed off and covered with fluid. Should the piston be held in with a lock ring? Anyway I blew the piston out and the seal looked good as expected since this is a new (last summer) sleeved unit. Not sure if there was any contamination on the seal. The finish on the sleeve is not really polished since I see machine marks.

[Ron]

Man!, the luck you are having with this...

Send it back!

[David T]

If it leaks either the cylinder is not smooth and round or the seal is bad or possibly both. If it was just sleeved contact the vendor you got it from. No leakage is acceptable.

[dn010]

It is probably the machine marks causing it to leak. There is also nothing holding the piston into the slave cyl except, when installed, the fork. The last cylinder I had was also from Hervey and it failed in the same way yours did (leaking out of the boot and ultimately all over my clutch!). I needed a replacement and wanted to buy from Rob but his cylinders were not ready at the time. I decided to buy the cheap 'Euro' slave cylinder from DeLoreanGo. It has been trouble free and it's actually even cheaper now than when I bought it in 2017.

[Bitsyncmaster]

It is probably the machine marks causing it to leak. There is also nothing holding the piston into the slave cyl except, when installed, the fork. The last cylinder I had was also from Hervey and it failed in the same way yours did (leaking out of the boot and ultimately all over my clutch!). I needed a replacement and wanted to buy from Rob but his cylinders were not ready at the time. I decided to buy the cheap 'Euro' slave cylinder from DeLoreanGo. It has been trouble free and it's actually even cheaper now than when I bought it in 2017.

Your probably correct. Either the machine marks or there was something on the seal. Any leak along the cylinder would cause leaking every time the clutch is used.

[Bitsyncmaster]

John is sending me a new slave and credit for return postage of the bad one.:)

[Bitsyncmaster]

I got the new sleeved slave from John. It's interesting that our slaves have 2 or three different internals (I remember John sold different rebuild kits for 3). The piston on the new one has the seal installed about a 1/3 of the way from the end. The old one had the seal right on the end of the piston. So the new one would not bottom out the seal if your clutch was using all the slave throw. Also I think this new piston is made of aluminum (non-magnetic) unlike the old one that was steel or iron.

Anyway, I bought some DOT-4 fluid today and did not see this bottle does not say LMA (low moisture absorption). This is CarQuest Wearever Brand. I thought all DOT-4 was LMA. Should I not use it?

[Chris 16409]

Castrol has re-branded their DOT 4 break fluid bottles. They no longer use the "LMA" nomenclature.

59050

This is what I have been using. It's getting hard to find locally. Amazon sells it though.

[David T]

That's the stuff. It is supposed to be the same as what they used to call LMA. They do call it synthetic but it really isn't. Dot 5 is synthetic (silicone) Dot 4 is mineral based. AKA paint remover (hint, don't spill it on painted surfaces!).

[FABombjoy]

Is there any evidence to support the need for Castrol GTLMA? It seems to be something that people have been saying for so long that nobody can remember why.

I'll start: I've ran Prestone DOT 4, ATE TYP 400 / Super Blue, Castrol GTLMA, and currently Motul 5.1. I've ran all of these fluids in both the clutch and brake systems with no issues to speak.

[DMC-81]

That's the stuff. It is supposed to be the same as what they used to call LMA. They do call it synthetic but it really isn't. Dot 5 is synthetic (silicone) Dot 4 is mineral based. AKA paint remover (hint, don't spill it on painted surfaces!).

David, do you have a source for that? I think that would be blatant false advertising if what you're saying is true. Although it is labeled as Dot 4, it also says that it exceeds Dot 3 and 4 specs and is billed as "Advanced Performance".

I did research on LMA when I was choosing brake fluid and I only found was that this product Replaced LMA but was not the Same as it.

[DMC5180]

Dana,

I did a quick search for The GT LMA MSDS and in the process ran across this communication between MG owner and Castrol product support.

This should answer your question.

https://uploads.tapatalk-cdn.com/20190118/dd78086f343ba490af744faddbc350db.jpg




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[David T]

Over at the Lotus forums someone did some research and that was the response. As for false advertising, if you include some minor amount of something synthetic you can claim synthetic. In the world of advertising you can claim a lot of stuff. For instance you can call your product juice if 5% of it is juice. DOT 4 does not mean synthetic. Products all the time claim they are the best. Does anyone believe that?

[SamHill]

....Hervey parts fail?

[Bitsyncmaster]

....Hervey parts fail?

That one did. He did send me a new one no questions asked.

[DMC-81]

Dana,

I did a quick search for The GT LMA MSDS and in the process ran across this communication between MG owner and Castrol product support.

This should answer your question.

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Over at the Lotus forums someone did some research and that was the response. As for false advertising, if you include some minor amount of something synthetic you can claim synthetic. In the world of advertising you can claim a lot of stuff. For instance you can call your product juice if 5% of it is juice. DOT 4 does not mean synthetic. Products all the time claim they are the best. Does anyone believe that?

Thanks Dennis. I decided to re-ask Castrol / BP today and here was the quick response:

Question:

TO: contactus_at_bp_dot_com

Hi There,

I understand that the below product replaced the former GTLMA brake fluid product (also pictured). However, I am wondering if GTLMA was simply RENAMED the product below, or if it is somehow different or enhanced.

Most importantly, is the new Castrol Brake Fluid DOT 4 pictured below truly Synthetic? If so, what percentage is synthetic (i.e. is it a blend or 100% synthetic) ?


New Product:
59055

Old Product:

59056

Thanks,
Dana

Response:

Thank you for contacting Castrol North America.

Castrol GTLMA has been renamed to Castrol Brake Fluid DOT 4. The product label and name has changed; however the formula has not been changed.

Castrol Brake Fluid DOT 4 (formerly Castrol GTLMA) has always been a fully synthetic brake fluid.

Thank you again for contacting Castrol, we value your patronage!

Castrol Consumer Relations


Basically, Castrol Brake Fluid DOT 4 (formerly Castrol GTLMA) is fully Synthetic. That's a good thing, as I use it for both the clutch and brake systems in the Delorean. I seems it is worth the extra trouble to seek it out. I can get it at a local motorcycle shop.

Thanks.

[Bitsyncmaster]

Found this on the internet.....so it must be true.

All DOT3 & DOT4 fluid is synthetic...ie it is man made and does not have a petroleum base. DOT3 & 4 can safely be mixed. HOWEVER DOT5 (or 5.1) brake fluid is silicone based and must NEVER be mixed with DOT3 or 4.

[FABombjoy]

5.1 is not silicone based, it’s the sequel to 3 and 4.

Whoever chose this numbering scheme needs to be brought to justice.

[Bitsyncmaster]

I put in the new slave from John. Bled about a pine through the system. So far no leaks. I cleaned the bottom of the transmission because if you have a slave leak it will drip from the there.

I pulled the mixture unit to remove and install the slave so I want to be sure no leaks before I put that back in.

[Bitsyncmaster]

Engine back running so took the D for a 10 mile round trip to the post office. Everything went well but seems maybe the clutch is grabbing a little lower than I remember. I will probably do another bleed of the clutch just in case there is any air in the system. It seems to shift smoother now. Now need to do a few more drives to build up my confidence again.