Warm issues with manual gearbox, 3rd and 5th

[VIN3802]

Hi all,

I have an issue with my gear changes when the car has warmed up after about 5 or 6 miles. When I change up or down to third it is very notchy and grinds occasionally. Also fifth gear is notchy and grinds occasionally when shifting up from fourth. The gears are perfectly fine when everything is cool for the first few miles. Fifth gear also seems to pop out and grind when you take your foot of the gas and the revs start to drop unless you hold the shifter in position.

I have changed the gearbox oil as recommended to a 80w 90 Valvoline Transaxle oil which has improved the feel of the shift in other gears but not solved my issues with third and fifth. I have also just had Earls hoses at Silverstone Race Circuit make me up a Stainless Steel braided hose to suit and fitted that as I have read that the old hose can expand when warm causing reduced clutch operation. This again hasn't solved my issues but has greatly improved the clutches feel and reduced the effort to disengage it.

PJ Grady in the UK did adjust the linkage for the guy I purchased the car from but didn't test it on the road as it wasn't at the time UK registered.

Any thoughts on what this could be? I haven't adjusted the linkage myself yet as I wanted to get some ideas from anyone who may have experienced this before. The car has covered 15k miles on the odometer so has not covered "spaceship" miles.

Cheers,

Mark

[John U]

I had a similar issue with second gear...crunching, popping out of gear. Mostly when cold however. I drained the 80w90 and use redline MT90. No issues now.

[PJ Grady Inc.]

The UN1 transaxle is somewhat prone to damage if the car is operated with a leaking hydraulic cylinder. Often the slide hubs are damaged when this occurs. Assuming your fluid is good, as you say it is, and the hydraulics are good (as in not leaking) then your particular problem is likely to be a damaged 3/4th slide hub and the third driven gear caused by a PO driving it with a leaking cylinder.
As for fifth the probability is a bent/damaged 5th gear fork (pops out of gear) and possibly a bad fifth gear slide hub (grinds into gear). Parts for these issues are hard to come by and expensive. I can probably supply you what you need if you can't source the parts locally. I am very familiar with this transaxle and have rebuilt dozens of them so I am rather confident that your problems will be solved by replacing these parts. Obviously a teardown and inspection is in order first to confirm the parts needed for the repairs. Sorry for the bad news but there is no magic bullet here!
Rob Grady

[David T]

The UN1 transaxle is somewhat prone to damage if the car is operated with a leaking hydraulic cylinder. Often the slide hubs are damaged when this occurs. Assuming your fluid is good, as you say it is, and the hydraulics are good (as in not leaking) then your particular problem is likely to be a damaged 3/4th slide hub and the third driven gear caused by a PO driving it with a leaking cylinder.
As for fifth the probability is a bent/damaged 5th gear fork (pops out of gear) and possibly a bad fifth gear slide hub (grinds into gear). Parts for these issues are hard to come by and expensive. I can probably supply you what you need if you can't source the parts locally. I am very familiar with this transaxle and have rebuilt dozens of them so I am rather confident that your problems will be solved by replacing these parts. Obviously a teardown and inspection is in order first to confirm the parts needed for the repairs. Sorry for the bad news but there is no magic bullet here!
Rob Grady

As bad as it may be, before you take things apart recheck the external linkage adjustments and check the rubber bushings in the linkage for wear or looseness. Make sure the level is correct and maybe even try Redline MT-90. It does sound like you have a bent 5th gear fork though.

[davidc89]

I noticed something similar with my car, except from 1st to 2nd gear. Doesn't happen every time when warm, but it does occur from time to time.

[PJ Grady Inc.]

That would be a damaged !st/2nd gear slide hub and adjacent gear. When it's time for a clutch that would be a practical time to split the cases and change those parts. I have them available now but could run out in the future.
I noticed something similar with my car, except from 1st to 2nd gear. Doesn't happen every time when warm, but it does occur from time to time.

[David T]

That would be a damaged !st/2nd gear slide hub and adjacent gear. When it's time for a clutch that would be a practical time to split the cases and change those parts. I have them available now but could run out in the future.

Problems with 2nd gear can also be caused by a bent roll pin. Happens when the clutch hydraulics leak, you don't get full release on the clutch, and you force shifts. Still means you have to pull the transmission and split the case but a roll pin is 49 cents. Gears and syncros are a LOT more expensive! First step is to make sure you have the transmission filled up to the level plug. A low level can also cause shifting problems. If you don't know when the oil was changed last or what kind is in there it is time to to change it. If the fluid in the clutch reservoir or the brake reservoir looks dark and thick it is also time to flush and change that.

[davidc89]

That would be a damaged !st/2nd gear slide hub and adjacent gear. When it's time for a clutch that would be a practical time to split the cases and change those parts. I have them available now but could run out in the future.

How much do those run?

[davidc89]

Problems with 2nd gear can also be caused by a bent roll pin. Happens when the clutch hydraulics leak, you don't get full release on the clutch, and you force shifts. Still means you have to pull the transmission and split the case but a roll pin is 49 cents. Gears and syncros are a LOT more expensive! First step is to make sure you have the transmission filled up to the level plug. A low level can also cause shifting problems. If you don't know when the oil was changed last or what kind is in there it is time to to change it. If the fluid in the clutch reservoir or the brake reservoir looks dark and thick it is also time to flush and change that.

Yeah I am not sure when it was changed. The next thing on my to do list was to check levels and what not and go from there.

Thank you,
David

[VIN3802]

The UN1 transaxle is somewhat prone to damage if the car is operated with a leaking hydraulic cylinder. Often the slide hubs are damaged when this occurs. Assuming your fluid is good, as you say it is, and the hydraulics are good (as in not leaking) then your particular problem is likely to be a damaged 3/4th slide hub and the third driven gear caused by a PO driving it with a leaking cylinder.
As for fifth the probability is a bent/damaged 5th gear fork (pops out of gear) and possibly a bad fifth gear slide hub (grinds into gear). Parts for these issues are hard to come by and expensive. I can probably supply you what you need if you can't source the parts locally. I am very familiar with this transaxle and have rebuilt dozens of them so I am rather confident that your problems will be solved by replacing these parts. Obviously a teardown and inspection is in order first to confirm the parts needed for the repairs. Sorry for the bad news but there is no magic bullet here!
Rob Grady

I was hoping for the magic bullet... I guessed it would be something more serious once I had tried all the other potential fixes and they failed. Looks like I brought a bad car then for a primium price! I am gutted. I spent all my savings and more to buy this car and it sounds like it's going to cost me dearly to get it right.

Thank you Rob for your help and advice.

[VIN3802]

As bad as it may be, before you take things apart recheck the external linkage adjustments and check the rubber bushings in the linkage for wear or looseness. Make sure the level is correct and maybe even try Redline MT-90. It does sound like you have a bent 5th gear fork though.

The rubber bushings seem ok to me, there isn't much play at all in that respect. I have seen a YouTube video on adjusting the cable for the shifter but is there any other adjustment that may be required... I think I'm clutching a straws here, just hoping for a good outcome I guess.

[David T]

The rubber bushings seem ok to me, there isn't much play at all in that respect. I have seen a YouTube video on adjusting the cable for the shifter but is there any other adjustment that may be required... I think I'm clutching a straws here, just hoping for a good outcome I guess.

Forget the youtube video and go to the source. Page F:07:01-:02 in the Workshop Manual for the adjustment procedure. Do all of the simple, external stuff before you do the more intensive, expensive stuff.

[VIN3802]

Forget the youtube video and go to the source. Page F:07:01-:02 in the Workshop Manual for the adjustment procedure. Do all of the simple, external stuff before you do the more intensive, expensive stuff.

Thanks David, I'm going to get in the garage now and study that page you have quoted. I hope it's something else other than what Rob is saying I really do... I can't understand why it would only do it when the car is warm.

[jwrayth]

Thanks David, I'm going to get in the garage now and study that page you have quoted. I hope it's something else other than what Rob is saying I really do... I can't understand why it would only do it when the car is warm.

Also since you're UK based then a good source of parts and advice is GTO Racing (http://www.gtoracing.co.uk/index.php?option=com_content&view=article&id=12&Itemid=112)

[chris williams]

I had a similar issue on my car when I re-commisioned it. I ended up replacing no's 13 & 17 along with all the bushes in this http://store.delorean.com/c-289-4-2-0-manual-shift-linkage.aspx along with replacing the oil with Lucas synthetic gear oil and it sorted everything out. Not sure what part did the trick but it has been OK for 3000 miles now!
Chris

[flux3d]

I had similar issues to this, all of which turned out to be poor adjustment of the gear selector. I got this sorted, changed the trans oil and lubed all the exterior mechanism. It also tended to pop out of fifth if you didn't keep your hand on the gear stick when lifting off the clutch. This doesn't seem to be a problem now.

One thing that occurred to me is do you still have the original clutch line? That runs down the car next to the hot cooling pipes and tends to swell once the car gets warm. This causes the clutch to not disengage when shifting and could cause the problems you mention.

Don't get too discouraged. These cars have a tendency to throw curve balls at you.

I'm up in Leicester, not far from me. I'd be happy to look over it for you. No expert but I've done loads on my car since i got it. Be happy to help, and it's always great to have a fellow owner near. :) sent me a message if you like.

[VIN3802]

I had similar issues to this, all of which turned out to be poor adjustment of the gear selector. I got this sorted, changed the trans oil and lubed all the exterior mechanism. It also tended to pop out of fifth if you didn't keep your hand on the gear stick when lifting off the clutch. This doesn't seem to be a problem now.

One thing that occurred to me is do you still have the original clutch line? That runs down the car next to the hot cooling pipes and tends to swell once the car gets warm. This causes the clutch to not disengage when shifting and could cause the problems you mention.

Don't get too discouraged. These cars have a tendency to throw curve balls at you.

I'm up in Leicester, not far from me. I'd be happy to look over it for you. No expert but I've done loads on my car since i got it. Be happy to help, and it's always great to have a fellow owner near. :) sent me a message if you like.

Thanks, that would be really helpful... I replaced my clutch line with a custom one which Earls Hoses at Silverstone Race Circuit made up for me. I did the transaxle oil replacement too using a GL5 80W90 as recommended (Valvoline). The oil which came out the box was really thin and black... The new stuff is thick and sticky like glue. I did filter out the old oil and didn't find anything extra in there.

34128

[VIN3802]

Also since you're UK based then a good source of parts and advice is GTO Racing (http://www.gtoracing.co.uk/index.php?option=com_content&view=article&id=12&Itemid=112)

Thanks James, that's good to know for parts if it comes to it... Will be a while if I do have to strip the gearbox (unless my numbers come in).

[VIN3802]

I had a similar issue on my car when I re-commisioned it. I ended up replacing no's 13 & 17 along with all the bushes in this http://store.delorean.com/c-289-4-2-0-manual-shift-linkage.aspx along with replacing the oil with Lucas synthetic gear oil and it sorted everything out. Not sure what part did the trick but it has been OK for 3000 miles now!
Chris
Hi Chris, I checked number 13 and 17 when I had my car up on its stands when replacing the clutch hose yesterday as a chap on YouTube had pointed those out to be a problem coming loose but mine seemed solid with little play at all. My whole linkage system seems to be well lubricated too which looks recent so maybe PJ Grady did it when they had the car for the PO. I have attached a picture of how my shifter sits in neutral... It looks right to me from what the Delorean Manual quotes but not sure whether the rods need adjusting or do they just determine where the shift pattern is?

34129

[chris williams]

It does all seem a bit odd, as Flux3d wrote these cars can seem to throw curved balls on occasions. I replaced all my clutch system less than 3 years ago with a new DMCH Master/Slave and DOC(UK) S/Steel clutch line and it seems that one of these has failed on me, again thats with only about 3000 miles of driving on them.
Certinally odd, may well be worth asking/contacting Martin Gutowski over on one of the UK forums, he did the video on YouTube that I guess your using for reference and he seems to know how to set up the linkages well.
As an after thought the reason number 17 is mentioned a lot as they did wear/break on the shaft. I cant remember what symptoms this caused but may be worth another check on this part.
Chris

[VIN3802]

It does all seem a bit odd, as Flux3d wrote these cars can seem to throw curved balls on occasions. I replaced all my clutch system less than 3 years ago with a new DMCH Master/Slave and DOC(UK) S/Steel clutch line and it seems that one of these has failed on me, again thats with only about 3000 miles of driving on them.
Certinally odd, may well be worth asking/contacting Martin Gutowski over on one of the UK forums, he did the video on YouTube that I guess your using for reference and he seems to know how to set up the linkages well.
As an after thought the reason number 17 is mentioned a lot as they did wear/break on the shaft. I cant remember what symptoms this caused but may be worth another check on this part.
Chris

Your master/ slave or line has failed in that short space of time? What shifting symptoms are you experiencing with this fault. My master and slave don't appear to be leaking but certainly don't look new. My reservoir hasn't dropped at all since yesterday and there are no signs of leaks on my system... I have just put her up on the ramps again to look and all seems fine. I have just checked 13 again and it looks fine and 17 seems to be holding things ok. I might remove it and have a closer inspection tomorrow just in case.
I'll see if I can PM Martin for some advice also... Thank you for your help :-)

[PJ Grady Inc.]

It's because the gear oil viscosity is so heavy when cold that it cushions the gears better and slows down shifting to the point of masking the warm fluid condition. I'm sorry but i'm pretty sure of the parts that you need but by all means try all external measures first to see if you can improve things a bit.
Rob


Thanks David, I'm going to get in the garage now and study that page you have quoted. I hope it's something else other than what Rob is saying I really do... I can't understand why it would only do it when the car is warm.

[PJ Grady Inc.]

I've seen quite a few DMCH slave and master (both brk. & clutch) cylinders fail within a couple years to be perfectly honest. We're sleeving all the cylinders with brass or stainless depending on "Garage Queen" verses "daily driver" conditions. Brass is best for the former and stainless the latter for reasons I will save for later. I'm working on sourcing/making new seals as my NOS stock dwindles down. These should last much longer than two years! We also carry the stainless slave pipe and braided fluid line and a hardened adjustable clutch link (at the pedal not the cl. mstr.) for shorter drivers or those that want to save on the cost of the braided line.
Rob


Your master/ slave or line has failed in that short space of time? What shifting symptoms are you experiencing with this fault. My master and slave don't appear to be leaking but certainly don't look new. My reservoir hasn't dropped at all since yesterday and there are no signs of leaks on my system... I have just put her up on the ramps again to look and all seems fine. I have just checked 13 again and it looks fine and 17 seems to be holding things ok. I might remove it and have a closer inspection tomorrow just in case.
I'll see if I can PM Martin for some advice also... Thank you for your help :-)

[PJ Grady Inc.]

Totally valid point David. A lot depends if the shifter feels rubbery/notchy as you go into 2nd. The broken pin leaves the shift rod and fork over shifting past the broken pin and then springing back into position with the help of....you guessed it...a spring! If it also grinds then it probably needs a slide hub either way but if there is usually no grinding the pin generally goes before the fork so this one could end on a better note. Either way however count on a day's labor for someone to pull the tranny and another one to split and rebuild it (less if you're me!!!).
Rob



Problems with 2nd gear can also be caused by a bent roll pin. Happens when the clutch hydraulics leak, you don't get full release on the clutch, and you force shifts. Still means you have to pull the transmission and split the case but a roll pin is 49 cents. Gears and syncros are a LOT more expensive! First step is to make sure you have the transmission filled up to the level plug. A low level can also cause shifting problems. If you don't know when the oil was changed last or what kind is in there it is time to to change it. If the fluid in the clutch reservoir or the brake reservoir looks dark and thick it is also time to flush and change that.

[PJ Grady Inc.]

I just spoke to Stephan at DMCH as I know their supply is very low and he was unsure if they have any available. If they do the cost is currently listed around $300- but they may not have any at that price. He said he'd check back with me soon/tomorrow. My cost from my English source is well above that so I guess you'd have to say it depends where you have to source it. As David said it may just be the 2nd gear roll pin is bad. PM if you want to discuss your particular symptoms.
Rob


How much do those run?

[Nicholas R]

This is just a side note, but since it's come up several times in this thread I figured I'd mention it. When I called Redline Oil, they specifically said that we should not run MT-90 in our gearbox, or any other transaxle where the gear train shares oil with the differential. The oil is designed strictly for helical and spur gears (and could even work in a bevel gear differential), but is not designed for sliding hypoid gears (pretty much every normal differential). It even says on the MT-90 website "not for use in differentials with hypoid gears."

Redline recommends using 75W-90NS in our transaxle. This is the same oil they recommend for Porsche, Subaru, and Ferrari transaxles.
http://www.redlineoil.com/product.aspx?pid=47&pcid=7

I know that people have run with MT-90 without any issues, but just be aware that the manufacturer recommends against it.

[VIN3802]

It's because the gear oil viscosity is so heavy when cold that it cushions the gears better and slows down shifting to the point of masking the warm fluid condition. I'm sorry but i'm pretty sure of the parts that you need but by all means try all external measures first to see if you can improve things a bit.
Rob

Thanks again For the advice Rob. Do you have an estimated price for the parts I need? I guess I will need to include new seals for the box too. Is the job very specialist and requires specially made tools or would you think it could be in the bounds of a home mechanic who has all the manuals to follow but never stripped a UN1 before?
Do your UK branch offer gearbox repairs or does it get outsourced?

Also you say potentially that external measures may improve things but is this just masking an issue that will in time only get worse? If I drive the car currently how it is now with all the mentioned symptoms what damage am I doing to the gearbox and will I make things worse? Will it damage other parts seemingly ok presently?

Sorry for all the questions but I don't want to cause more damage and I need to know whether to just leave it in the garage until I can afford to do the repairs.

Cheers,

Mark

[DMCMW Dave]

This is just a side note, but since it's come up several times in this thread I figured I'd mention it. When I called Redline Oil, they specifically said that we should not run MT-90 in our gearbox, or any other transaxle where the gear train shares oil with the differential.

Redline recommends using 75W-90NS in our transaxle.
.

I've heard the same thing when I talked to RedLine. My personal experience, others may vary, is that even the 75W90NS may be too "slippery" and cause the occasional gear crash. I switched back to standard 80W90 and the problem went away.

It is important to change the gear oil once in a while (30K miles is the recommended interval), but in my experience using oil that's "too good" can cause issues.

[PJ Grady Inc.]

Probably the best way to fix this would be as an exchange for a fully reconditioned transaxle due to the rarity and expense of the particular parts you will need. Your problems may gradually get worse and it's hard to say whether more parts will be damaged or just the same parts damaged further. Yes I meant you may be able to mask the internal problems but they're not likely to go away. If you sent the box over I would replace needed gears, all seals and gaskets and glassbead the cases to look as new. See attached photo. Please PM for further info if you're interested.
Rob



34139

Thanks again For the advice Rob. Do you have an estimated price for the parts I need? I guess I will need to include new seals for the box too. Is the job very specialist and requires specially made tools or would you think it could be in the bounds of a home mechanic who has all the manuals to follow but never stripped a UN1 before?
Do your UK branch offer gearbox repairs or does it get outsourced?

Also you say potentially that external measures may improve things but is this just masking an issue that will in time only get worse? If I drive the car currently how it is now with all the mentioned symptoms what damage am I doing to the gearbox and will I make things worse? Will it damage other parts seemingly ok presently?

Sorry for all the questions but I don't want to cause more damage and I need to know whether to just leave it in the garage until I can afford to do the repairs.

Cheers,

Mark

[chris williams]

I've seen quite a few DMCH slave and master (both brk. & clutch) cylinders fail within a couple years to be perfectly honest.
Not wishing to detract from the point of the thread, nor start DMCH bashing for having brought a product to market but 2 years really? On a car that's used weekly is that the best a BRAND NEW not NOS part lasts nowadays? It's the master that's failed/failing, do they do re-build kits for them? What's failing on them?
Chris

[PJ Grady Inc.]

I don't want to start a flame either I was just making an observation of a problem for all of the vendors. I think the issue is that most of the aftermarket parts for 8o's era cars are now made in China and quality just isn't job one anymore if it ever was! All of the old British and French aftermarket companies that supplied these types of parts are long gone and no one is taking thier place except China. No one is currently making rebuild kits except John H. and his fail after a year too so that is not the answer. China is not the answer!!!
We are making drawings of all the hydraulic seals to shop to an American manufacturer and I'm hoping this will solve the problem combined with sleeving the cylinders.
Rob



Not wishing to detract from the point of the thread, nor start DMCH bashing for having brought a product to market but 2 years really? On a car that's used weekly is that the best a BRAND NEW not NOS part lasts nowadays? It's the master that's failed/failing, do they do re-build kits for them? What's failing on them?
Chris

[David T]

Redline MT-90 is not necessary for the UN-1 in the Delorean. It is being used in the Lotus application of the UN-1 with good results so far. For the Delorean any good GL-4 80-90W gear oil is fine. It is easier to source a whole transaxle than to get some of the bits. It would be a shame to have to do that if all you really need is the 49 cent pin though. It doesn't require any special tools to split the transaxle open for inspection and cleaning. If, after opening the unit, you find gears crunched up, then you might replace the whole thing. Parts can be found but they are not readily available nor inexpensive.