Weird stuff happened with my transmission - any ideas?

[JohnZ]

Hi there folks! I come to you with some weird stuff happened to my car last night.

I was driving carefree through a local mountain pass, which is not even the hardest one in my area, switching gears pretty normally and going up and down several slopes. I always had a slight difficulty to put in 1st and 2nd, as probably many of you have as well, and yesterday was no exception. One thing to notice is that it was very cold, around 2C/35F.

When I came to the top of the hill I stopped at a traffic light, ?cause the subsequent downhill is winding and very narrow, so you have to wait for other cars to come up the other way before hitting the road yourself. After about 3 minutes of idling, the light became green and I proceeded to put the car in first gear, and I could not make it! The second gear was stuck as well, and I heard a sudden loud noise coming from either the gearbox or the clutch area, or maybe even the gearstick zone. Luckily I was already downhill, so the car started to gently slide down the road, so I could go and manouver myself down the pass while in neutral. I was then able to put the 3rd gear on, and from then on I just stuck with it, until I arrived at my destination.

Now: some things to clear in order to give you the whole context:
1) the clutch has been replaced and flushed some months ago
2) master and slave were replaced around 2014, and I have the stainless clutch line
3) it was cold
4) I just came, as I said, from a moderately hard driving up steep slopes and turns
5) more importantly: when I finally came to my destination, after a long descent, I tried to put the car in 2nd and it went beautifully
6) after a 5 hours stop, I took the car and headed back home: the car switched gear perfectly, as if nothing ever happened. :)

The question is: what actually happened? Could it be that the fluid in the clutch line went hot and could not operate the system? Could it be that the clutch was someway temporarily stuck? But why? The ?heat? element, anyway, is the only thing that comes to mind.

Fun fact: I was with my girlfriend, and she was scared to death, because the moment in which I lost power over the gears was so inappropriate? cars behind me, a really narrow and steep and winding road ahead of me, not fun! :) Also the bang from underneath? and I said ?Welcome to the DeLorean world, baby!? :)

I will leave it to you gentlemen, for my and my girl came up with a charming yet unscientific answer: the DeLorean was just jealous that I was hanging aroud with another gal! The DMC threw a tantrum! :)


PS: it happened before, but back then it was a linkage problem that was fixed, as per this thread: https://dmctalk.org/showthread.php?10821-Unable-to-shift-1st-and-2nd-gear&highlight=gear

[dn010]

An easy test for when this situation happens is to put it in neutral and pump the clutch pedal multiple times, and then try to shift. If it will shift, then you know it is hydraulic related. If not, then linkage related or something other than hydraulics. As for the loud noise, it could be that you were trying to force it into gear with the clutch not fully disengaged (did it sound like a grinding noise?).

I'm sure you have upgraded by now but worth asking - do you still have the plastic clutch line or is it now the stainless braid line?
Last time you flushed the clutch hydraulic system?

I would check the hydraulic circuit, then go over all the linkages to make sure nothing came loose. Of course, since you had issues with the crossgate cable coming loose previously - check that as well.

As long as everything is in order (you have proper gear oil level, etc.), the temperature shouldn't be a factor (unless you have plastic clutch line), I drove this car in all sorts of conditions, especially lots of snow when I used to live in New York. The DeLorean was actually pretty great in the snow. Only problem I ever had was when the pivot bolt broke on me in the middle of a winter drive. After 20+ years, I don't remember what gear I was in but I rode that gear most of the way home and made it. I do recall slam shifting it a few times but kept it minimal so I didn't damage anything.

Also, if you have never replaced the shift linkage bushings, this kit really made a huge difference for me, you might look into it, it really got rid of a lot of play (slop) in the linkage:
https://store.classicdmc.com/k100776-manual-trans-shift-bushing-kit.html

Lastly, a new crossgate cable also worked wonders for me. All those years driving in snow took a toll on my original cable where it wouldn't move as smoothly. Obviously you'll want to find these parts closer to home than Houston, but the links are examples of what I am talking about. I don't know if anyone makes NEW crossgate cables but the last one I got from DMCH was unusable - they are NOS and the threads where the adjusting nuts were damaged. I did not discover the damage until a long time after the purchase so I now have a $60 cable that I can't use.
https://store.classicdmc.com/101363-manual-trans-crossgate-cable.html

[JohnZ]

Thanks Dan! In point 2 of my notes I wrote that I have the braided steel clutch line indeed!

Also: if it was the misaligned linkage, shouldn't I be having difficulties in any situation? Instead, I just had troubles after some steep slopes and what I would consider "mildly heavy load" on the car, clutch and engine. Besides: soon after the whole thing found relief (cool breeze and fresh air, thanks to a gentle glide down the road with nothing but the brakes on duty)... it just went fine again.

My speculation is that the system I currently use, in terms of linkage adjustment, bleeding and so forth, is good until it works into a certain "window". If things are pushed a little too far, someway the system can't handle heavy loads or sporadic heat. Maybe I need to flush the system once more, or align the linkage just a tad to give the system some "room"...

I don't really know if what I'm saying makes sense... :)

EDIT: thanks for all the precious infos and the links! I will begin with a step by step check of the system, that, I'll say it once more, is working adequately on regular driving and just acted weird once, under those circumstances that I described!

[Bitsyncmaster]

Thanks Dan! In point 2 of my notes I wrote that I have the braided steel clutch line indeed!

Also: if it was the misaligned linkage, shouldn't I be having difficulties in any situation? Instead, I just had troubles after some steep slopes and what I would consider "mildly heavy load" on the car, clutch and engine. Besides: soon after the whole thing found relief (cool breeze and fresh air, thanks to a gentle glide down the road with nothing but the brakes on duty)... it just went fine again.

My speculation is that the system I currently use, in terms of linkage adjustment, bleeding and so forth, is good until it works into a certain "window". If things are pushed a little too far, someway the system can't handle heavy loads or sporadic heat. Maybe I need to flush the system once more, or align the linkage just a tad to give the system some "room"...

I don't really know if what I'm saying makes sense... :)

EDIT: thanks for all the precious infos and the links! I will begin with a step by step check of the system, that, I'll say it once more, is working adequately on regular driving and just acted weird once, under those circumstances that I described!

Since it was just first and second gear, my guess is cross gate cable adjustment. The pull up for reverse stop may have limited your movement left.

[dn010]

You may want to re-read what I posted, because I edited the post one minute before you responded.

What you are saying does make sense. However, the transmission needs two things to shift: it uses shift linkages that have numerous bushings and bolts, and also the crossgate cable which is what you adjusted the last time.

Try getting the car up and checking those things out. Who knows, perhaps the adjusting nuts came loose again?

[JohnZ]

Thanks Dave and Dan! To add a note: I flushed the circuit on September 2024 last time, when I replaced the clutch itself! And with the clutch and seals and stuff I also replaced a couple of bushings on the linkage! The pivot bolt I guess it's original, better put that in the cart as soon as possible...

You're right about pointing the difference between cable and linkage! I sometimes make one thing of two! :) I definitely adjusted the cable back in 2014, I think I will have to check on the fluid once again, and maybe give the cable that extra mm towards 1st and 2nd gear that is needed, just for safety... without sacrificing 5th gear of course.

Anyway, kudos to myself for not losing my cool and readily switching to 3rd to save the day... instinct, plus a bit of knowledge, makes wonders! :)

[Helirich]

This is suspiciously close to my experience. I was driving long distance. Not much for hills, but I was driving for 5 hours straight. Once off the highway, came to a light and couldn?t seem to get it in first. Was able to get second and proceeded. While I was driving, heard and felt a loud bang. Wasn?t sure if I hit something on the road that sprung up into the chassis. Anyways, had trouble for the rest of the 15 minute trip.

The next day, I pumped the clutch several times and it worked fine. I bled the clutch system and all worked in a test drive. I made the long trip home again and had trouble again in the last 10 minutes from the interstate to my house. I have made multiple 1 hour trips and have no problems.

I really don?t know what it was and if it is cured. I also don?t know if that noise was related. I looked under the car and didn?t see anything scraped up.

This all happened over a year ago and I?m just crossing my fingers. I pump the clutch Everytime I get in now.

[JohnZ]

Must be something related to traffic lights! :D

What bugs me it's not specifically what could go wrong in a transmission system, we sort of established that. What is weird is "why suddenly the thing doesn't work and after a while everything is back to normal?"

Similarly to Helirich, I've taken way longer trips with no issues (lately I went from middle Italy to the north-eastern part in an almost non stop 12 hours driving session), and also I've gone through mountain passes way steeper, longer and twistier than that, in that very journey by the way... and everything was fine.

It's paramount we find the key differentiator!

[Bitsyncmaster]

Cold would shorten the cross gate just a little. The cold could also make any grease if any in the cable move harder. There is not much movement there considering you need four positions, R, 1 and 2, 3 and 4 and 5th.

[Rich]

Must be something related to traffic lights! :D

What is weird is "why suddenly the thing doesn't work and after a while everything is back to normal?"

It's paramount we find the key differentiator!

Yes, you are asking good questions in order to prevent another such episode.

I suggest you inspect the location of your braided SS clutch line, particularly to see how close any section of this line is to the exhaust crossover pipe.

A theory explaining the failure is that some part of the line was too hot and the clutch fluid temporarily vaporized inside that section. This will prevent proper clutch disengagement until the line cools off.

When you idled the car after a long uphill drive the exhaust would be extra hot and there would be little cold air around the clutch line with the car stopped in traffic. Later on things are thermally different back there and the clutch/transmission runs normally.

The only thing this idea doesn't explain is how you were eventually able to start in 3rd gear to drive away at the top of the hill. Maybe the exhaust crossover was radiating less heat after 3 minutes of idling?

In any case see if you can get a look from below to check that the clutch line isn't very close to any of the exhaust components. I don't have a spec to share on the clearance.

Summary: Try relocating the line, just suspending it further from the crossover, using some bent steel wire as a temporary test, then drive the same route, speed, traffic idle and see if the problem disappears. If it's fixed then find a permanent way to relocate the last section of the line.

[Patrick C]

I think it couldn't hurt to change the clutch hydraulic fluid and bleed it again. I know it's less than 1.5 years old, but it could have moisture in it.

[JohnZ]

Thanks to all of you Dave, Rich and Patrick! Great inputs there! ;)

Knowing what we know about the transmission system, I think we have to start from the facts. To be precise, I think I didn't really start in third gear, I believe I just let the car roll down the hill in neutral, moved simply by gravity, and then, once I felt I had enough momentum, I maneuvered the 3rd gear in, to be ready with some power if needed. Another fact: this was a temporary problem, so whatever caused it was time-based, such as heat. After a simple 5 minutes cool down (moreover... still driving) the shifter was already back in business.

The routing of the clutch line is a good clue, I will look into that for sure! Also the shrinking cross gate cable is a good theory...maybe I can give it some more room, just a little notch!

Lastly, replacing the fluid and bleeding again carefully is a very simple task, so that can be done for some peace of mind!

Again, my guess is that my shifting is working on a narrow and tight band that is more than adequate 99% of the time. Now, when a series of causes present themselves all together and the system is forced to work outside that band...troubles begin, until the conditions come back to normal/average. So I think it may be wise to widen that band and consequently push the "limits the system works within" a bit further. This by setting the cable, bleeding the clutch, checking the routing of the clutch line and so on.

I hope I made myself clear with all this gibberish! :)

[David T]

Here is what I would do. Reflush and bleed the clutch hydraulics. It is possible you could have some air in it. Use DOT 4. Change the oil in the trans and use Redline MT-90. Check ALL of the rubber bushings in the shift linkage and go over all of the adjustments. A 1/4 turn may be all you need to make it better. If the shift lever has any play or "slop" in it, find the source and fix it. Check the transmission mounts for cracks. A cracked mount will mess up the shift linkage adjustments. Lubricate the shift linkage so it moves smoothly and that there is no lost motion. As mentioned it is a great idea to make sure the clutch hydraulic line is not close to any exhaust pipes. You should not have trouble with the 1-2 shift. If it persists you have a bent roll pin. The bad news is to replace that $0.29 pin you have to remove and disassemble the transmission!

[JohnZ]

Thanks David! I?ll see what I can do and especially WHEN I can do! :)

Another thing that comes to mind: is there a way to reduce the play between the pedal and the pushing rod on the clutch master? I have a couple of millimeters in which nothing happens, before the rod actually pushing? that could make me gain some travel on the fork I guess!

Any ideas?

[JohnZ]

Another thing that has come to my mind: when I installed the new braided stainless steel clutch line I was young, I was a fool and I was reckless. It was quite some years ago, and it was one of the first jobs that I did on the car.

The question is: is there a dedicated routing for the clutch line? Are there any clips or forced channels where the line is supposed to rest as per factory specs?

I have always felt as if my clutch line was just hanging there, unsecured and unsupported... It works, though... But maybe it can work even better if properly seated!

[David T]

Thanks David! I?ll see what I can do and especially WHEN I can do! :)

Another thing that comes to mind: is there a way to reduce the play between the pedal and the pushing rod on the clutch master? I have a couple of millimeters in which nothing happens, before the rod actually pushing? that could make me gain some travel on the fork I guess!

Any ideas?

There is a shoulder bolt on the pedal that connects the linkage rod. On some cars I have seen the shoulder worn enough to introduce some lost motion. Get under the dash and move the pedal and see where the motion is lost.

[dn010]

I have the same issue with my car. Lots of travel from the pedal before it engages the clutch master cylinder. I have no wear and was trying to locate an adjustable linkage with no success. My car takes off with as little as 1/4" of pedal travel off the stop on the floor. Let me know if you find anything on your car that may be the cause.

[Emit]

There is a shoulder bolt on the pedal that connects the linkage rod. On some cars I have seen the shoulder worn enough to introduce some lost motion. Get under the dash and move the pedal and see where the motion is lost.

Agree

That shoulder bolt is a sneaky one, at first inspection you can't see it, you have to take the linkage apart at the pedal, but if you get under there and move the pedal by hand you'll see the slop in the linkage. Mine was nearly worn through completely, I was close to losing the clutch! Once I replaced it the car was much nicer to drive

[JohnZ]

Agree

That shoulder bolt is a sneaky one, at first inspection you can't see it, you have to take the linkage apart at the pedal, but if you get under there and move the pedal by hand you'll see the slop in the linkage. Mine was nearly worn through completely, I was close to losing the clutch! Once I replaced it the car was much nicer to drive

That's interesting! I will do an inspection as soon as possible!

By the way: can you please pinpoint the exact bolt you are referring to in this schematic? https://store.classicdmc.com/parts/brakes-wheels/6-4-0-pedal-box.html?srsltid=AfmBOort08VBKyVGr51ZjZl9UVfFeSYgO tRYPjjfvEAH8XBw4bUoYebZ

Whenever I rest my foot on the clutch while driving, as a rest pedal, I really feel as if I could take advantage of that extra play to gain some travel at the clutch itself... I can't really quantify it, but it's at least 5 mm of nothingness! Gotta find this bolt and check it out! :)

[Timeless]

Whenever I rest my foot on the clutch while driving, as a rest pedal, I really feel as if I could take advantage of that extra play to gain some travel at the clutch itself... I can't really quantify it, but it's at least 5 mm of nothingness! Gotta find this bolt and check it out! :)
You rest your foot on the clutch pedal while the trans is in gear and driving? That is terrible for the clutch.

[JohnZ]

You rest your foot on the clutch pedal while the trans is in gear and driving? That is terrible for the clutch.

I sometimes do (not all the time, to tell you the truth... most of the times it's just laying on the carpet), but when I do I feel that the pressure that is applied by my tiny foot at rest is nowhere near the pressure needed for disengage the clutch even slightly! Especially on our clutches pedal that are notoriously hard as stones! But I definitely feel the play on the pedal, that I guess can be fixed someway!

BUT if it really that terrible for the clutch... I'll change habits rightaway :)

[Rich]

BUT if it really that terrible for the clutch... I'll change habits rightaway :)

Yes, it is a bad idea to press the clutch pedal unnecessarily.

Before the pedal starts to disengage the clutch (which requires some pedal pressure as you note) the pedal causes the one face of the clutch throwout bearing to begin spinning against the fingers of the clutch pressure plate. It does this with very little pedal pressure. With your foot resting on the pedal you might be engaging that bearing.

That bearing face isn't meant to spin all the time. The free play in the clutch pedal assures no unnecessary spinning of the throwout bearing.
So best practice is to never touch the clutch pedal unless you need to disengage it while starting the engine, shifting or while idling in gear for a short time. You want that bearing to last longer than the clutch lasts.


The solution for resting the driver's left foot in a DeLorean? If yours doesn't have one already then install the Dead Pedal Kit (https://store.classicdmc.com/k111662-dead-pedal-kit.html). The dead pedal was added later in production. (check out the 5-star reviews on the parts listing page)

It also helps the driver stay in position during tight righthand turns at speed.

[dn010]

Check out this diagram to see the pedal linkage and what to check:
https://store.classicdmc.com/parts/manual-transmission/4-4-0-clutch-pedal-linkage.html

[JohnZ]

Ok thanks Rich that was very informative! I still find it hard to believe that the tip of my foot gently laid on the pedal and barely applying the lightest of the pressures can have such an effect! But I trust you on that! :)

Anyway I do that exclusively in traffic situations, to be ready to shift frequently... generally speaking my foot is on the carpet! Also all the clutch related items were replaced about a year ago, so everything is pretty much brand new! Let's keep it as fresh as we can though! :)

I'll surely get in there and see if I can make the pedal feel tighter! One of the downsides of owning such a rare car is that you don't often have other cars to compare yours to! Not that readily anyway... Don't you agree?

Maybe sometimes some things are just the way they are and certain features are just simply shared by other cars, and are supposed to be that way! :)

[Rich]

Ok thanks Rich that was very informative! I still find it hard to believe that the tip of my foot gently laid on the pedal and barely applying the lightest of the pressures can have such an effect!

....One of the downsides of owning such a rare car is that you don't often have other cars to compare yours to! Not that readily anyway... Don't you agree?


Two things:

1. It may be possible your very light resting of your foot will not engage the pivot arm and the throwout bearing. It depends on how much force is on the pedal. You could test someday with a friend and with your car raised for inspection. When you on the clutch pedal with your normal force your friend looking up from beneath the car can tell you whether the Clutch Release Arm is being moved by the clutch slave cylinder. If the arm does NOT move from its rest position in this test then your foot-resting-on-pedal will not cause premature bearing failure. The force from your foot may not be enough to overcome the return spring (in the pedal box) on the clutch pedal and start to activate the release mechanisms.

2. Yes, I'm sure it is a downside for a DeLorean owner not to be located near a reference car.

Luckily you will have many opportunities to explore other DeLoreans in Belfast in June. I look forward to meeting you there (without my car).

[JohnZ]

You being in Belfast next June comes as a great surprise! As years pass by I get more and more involved in the technical and also human aspects of DeLorean ownership! So I'm sure that this eurofest is going to be even more fun and interesting for me than the last time I went there in 2016! :)

Just for fun this morning I made a short video about what I mean by occasionally resting my foot on the clutch pedal, as you can see the weight of the foot applies but a tiny pressure, that is maybe or maybe not triggering anything back there! I'll give you the link so you can judge by yourself! :)

https://youtube.com/shorts/XYnK2gwux_c?si=kWO8GIYT_8nq9eA-

[Rich]

Thank you. That video tells some of the story.

From viewing it 3 times I cannot be sure the shaft to the master cylinder is moving forward or not from its rest position. For sure the clevis pin at the end of the pedal linkage moves/rotates but this alone may not be enough to move the clutch release fork and engage the throwout bearing.

An inspection with your foot at the pedal while a friend looks at the slave cylinder and release fork may help verify your light foot pressure is OK. If the release fork does not move that's good proof your foot pressure isn't a problem.

For extra credit you can also test with your friend's help to discover how much foot pressure is needed to start any movement at the slave-fork connection. Then you will know the practical "resting" foot force limit.

[JohnZ]

Next time I will have the car on the lift I will surely check that!

I can assure you that the push rod at the master cylinder doesn't move when I rest my foot on the pedal, hence my disbelief towards the fact that it could be such a terrible thing to do :)

basically what the foot does by resting there is taking advantage of the play of the whole leverage... In other words that little pressure gets lost well before the rod starts to push... that is my take :)

[Helirich]

I believe you are safe. There is a lot of play there at the pedal. I?ve always wanted to make a new link to get rid of that play. I believe they sell them, but it really would be easy to make something. Just need to find the time. You can feel when you are actually doing something back there. If you want confirmation, I believe someone could reach the arm from above while you try it. Don?t need to lift the car.

[David T]

I believe you are safe. There is a lot of play there at the pedal. I?ve always wanted to make a new link to get rid of that play. I believe they sell them, but it really would be easy to make something. Just need to find the time. You can feel when you are actually doing something back there. If you want confirmation, I believe someone could reach the arm from above while you try it. Don?t need to lift the car.

There is no definitive definition of "Light Pressure". Any pressure can be enough to cause the throwout bearing to come in contact with the pressure plate and over time it will prematurely wear out the throwout bearing. Best practice is to never rest your foot on the clutch pedal. Use the "dead pedal" and if you don't have one, get one. Same thing for the brake pedal, never rest your foot on it either or you will drag the brakes. While we are talking about pedals make sure the floor mat cannot interfere with the gas pedal.

[r00b]

I've combined an autozone master cylinder and a fork from a different master cylinder, my setup moves the engagement point towards the middle of the pedals travel.