Crunching Of Third Gear

[Tillsy]

When cold she works an absolute treat - when warm third gear Crunches into place, I can feel and hear the cogs crunch in.

All other gears are fine, and double clutching makes non difference.

For now I'm just revving a little higher in second and going straight to fourth, but keen to hear opinions what might be the cause of third doing this only when warm?

[Nicholas R]

Eeeek. Possibly a bad synchro for 3rd gear? Not sure how heat would affect that though...

[Tillsy]

Eeeek. Possibly a bad synchro for 3rd gear? Not sure how heat would affect that though...

Cheers - DMC5180 was thinking the same thing, but my realisation it only happens once warmed up is odd...

I will change the oil this week, can't vouch for its level or age, not sure if that would have such a highly specific impact though?

[DMCMW Dave]

Cheers - DMC5180 was thinking the same thing, but my realisation it only happens once warmed up is odd...

I will change the oil this week, can't vouch for its level or age, not sure if that would have such a highly specific impact though?

Not odd at all. When cold the oil is much thicker. Not necessarily a bad synchronizer blocking ring, more likely a bad sliding gear.

[DMC5180]

FYI: the Drain plug is 10MM and usually very tight. a 10MM square plug or 8 pt. socket works best. Tranny oil capacity is 0.9 gal (3.4L)

This is what the 3rd gear Synchro ring looks like.

11976

[DMC5180]

Not odd at all. When cold the oil is much thicker. Not necessarily a bad synchronizer blocking ring, more likely a bad sliding gear.

Certainly possible,especially if crunching for a long time. (excessive wear) But the ring must run interference in order to slow the rotating assembly. I suppose it could also be possible the Buffer springs could have failed or fallen out but that would hard to believe.

Remember the weird thing that happen to me with first gear where the synchro didn't function at all. It's been flawless since I fixed it.

[David T]

The amount and type of oil is very important. If you do not know exactly what kind of oil is in there the best advice is to just change it. Before you drain it make SURE you have removed the level plug FIRST! You do not want to find yourself having trouble getting the level plug out and no oil in the transmission! You should get a good brand hypoid gear oil GL-5. If you can find it, Castrol HYPOYC SAE 80W-90 is good or Redline MT-90. You may also need a minor adjustment in the shift linkage or some of the rubber washers may be worn. Do not overfill. It should be filled up to the bottom of the level plug when cold and the car is level. The drain plug should have a magnet on it. If it doesn't you can get them.
David Teitelbaum

[DMCMW Dave]

FYI: the Drain plug is 10MM and usually very tight. a 10MM square plug or 8 pt. socket works best. Tranny oil capacity is 0.9 gal (3.4L)
This is what the 3rd gear Synchro ring looks like.


And it won't be bad. The sliding gear is what fails. The points on the inner teeth get blunted and then it won't slide into the driven gear.

[DMC5180]

The amount and type of oil is very important. If you do not know exactly what kind of oil is in there the best advice is to just change it. Before you drain it make SURE you have removed the level plug FIRST! You do not want to find yourself having trouble getting the level plug out and no oil in the transmission! You should get a good brand hypoid gear oil GL-5. If you can find it, Castrol HYPOYC SAE 80W-90 is good or Redline MT-90. You may also need a minor adjustment in the shift linkage or some of the rubber washers may be worn. Do not overfill. It should be filled up to the bottom of the level plug when cold and the car is level. The drain plug should have a magnet on it. If it doesn't you can get them.
David Teitelbaum

The magnetic plug from DMCH is too tall. I bought one and it hit the Ring gear before it was tight. It would work fine if the ring gear was on the other side, but as we all know that would be bad.

[DMC5180]

And it won't be bad. The sliding gear is what fails. The points on the inner teeth get blunted and then it won't slide into the driven gear.

Too bad it's one of those $0.00 parts at DMCH.

[DMCMW Dave]

The magnetic plug from DMCH is too tall. I bought one and it hit the Ring gear before it was tight. It would work fine if the ring gear was on the other side, but as we all know that would be bad.

There is a very powerful magnet already inside the trans anyway. Unless you left it out.

That's funny - they show a magnetic drain plug online but I've never stocked one.

[DMC5180]

There is a very powerful magnet already inside the trans anyway. Unless you left it out.

That's funny - they show a magnetic drain plug online but I've never stocked one.

I have photographic evidence that my magnet is installed. I bought the magnetic plug as one of those why not it won't hurt anything. (It just didn't work as planned) :-)

[jawn101]

There is a very powerful magnet already inside the trans anyway. Unless you left it out.

That's funny - they show a magnetic drain plug online but I've never stocked one.

I think I got a set of the magnetic drain plugs from you, Dave. Unless those dropped straight from Houston. Actually I think they did. I don't believe I had any trouble installing them though Dennis.

[DMC5180]

I think I got a set of the magnetic drain plugs from you, Dave. Unless those dropped straight from Houston. Actually I think they did. I don't believe I had any trouble installing them though Dennis.

Set?

If you put one in the fill plug hole it won't be very effective. But It won't hurt anything either. The oil will splash around though. In My case I attempted to install the magnetic Drain plug the same number of turns as the old plug. It crunched the ring gear and broke the magnet a couple turns shy of the original plugs exterior protrusion height. I wasn't about to simply back it off a couple turns and run the risk of it falling out or leaking.

[jawn101]

Set?

If you put one in the fill plug hole it won't be very effective. But It won't hurt anything either. The oil will splash around though. In My case I attempted to install the magnetic Drain plug the same number of turns as the old plug. It crunched the ring gear and broke the magnet a couple turns shy of the original plugs exterior protrusion height. I wasn't about to simply back it off a couple turns and run the risk of it falling out or leaking.

Yeah, I accidentally rounded off my plugs during the transmission overhaul, so I ordered 2 replacements. They both came with magnets on them. I didn't see any evidence that they were hitting anything inside though, I will double check that! :)

[kings1527]

Chris, did you find a solution to this?

I'm having a similar issue with first gear. I changed my oil with 80-90 and I still have it but not when it's cold (like Dave was talking about). If I'm at a light when it turns green and I push the clutch in quickly and put it in first, sometimes it'll crunch. If I shift to second before going into first, it's fine.

When I first started driving my car after it had been sitting for several years, it was pretty consistent. Now having driven it close to 6k miles along with a trans oil change, it's somewhat rare and only if it's warmed up.

I had someone recommend getting rid of the adjustable link at the pedal and going back to the original link. Maybe try an 85-90? Any ideas?

[refugeefromcalif]

An old thread that I missed and discribes Perfectly the problems I've been have with my transmission. Shifting cold is no problem, after it warms up, then it all starts.

Double clutching when Down shifting into third works fine, Up no. If I upshift slowly to third though, it's OK.
I'll go ahead and change my fluid to see what happens, (because I don't know when it was changed last). I assumed DMCF did but,...

Alex, I've noticed the same thing when shifting into first after sitting at a stoplight.

I brought this up an another thread a bit back and Dave S. brought up the synchro issue.

George

[DMCMW Dave]

If I'm at a light when it turns green and I push the clutch in quickly and put it in first, sometimes it'll crunch. If I shift to second before going into first, it's fine.



That's actually pretty normal.

[kings1527]

That's actually pretty normal.

:aniclap:

Excellent...I guess I'm not going to worry about it! I'll monitor it and if it gets worse, I'll go from there. Thanks again, Dave.

[David T]

:aniclap:

Excellent...I guess I'm not going to worry about it! I'll monitor it and if it gets worse, I'll go from there. Thanks again, Dave.

This is also an "issue" with the transaxle in the Lotus. Their solution was a magic elixir called Castrol TAF-X 75W/90 with the appropriate Lotus part #. Don't get too excited about this. For a long time it was only available at Lotus dealers in the US who would pony up the big bucks for it and buy it in 5 gallon pails. Some would dole it out to anyone who wanted it and had a can and a lot of money. Now it is unavailable. Maybe some dealers still have some old stock. What everyone is using now is Redline MT-90. A LOT cheaper and locally available. Lotus won't recommend it because they haven't tested it. No surprise, the newest car that last needed it is 2004 and they are not about to spend a lot of time or money supporting it. From anecdotal evidence it seems to be at least as good as TAF-X. I am not saying you should use MT-90 in the Delorean. You should be able to use any good hypoid GL-5 goop since we are only pushing 130 HP as opposed to the Lotus running 350 HP. The key is to use a GOOD fluid. If you do not know what is in there or how long it has been in there, it is time to change it. If the rubber bushings in the linkage are worn it is time to change them. If you are crunching it may be time to replace the clutch. If, after all this you still have trouble shifting, you may have to replace the syncros. Any time you have trouble shifting and you are pulling the transmission to replace the clutch, IMHO the transmission should be opened and inspected. If for no other reason than to replace the roll pins in the shift linkage. If, at any point in the car's history, the clutch hydraulics did not work properly and the driver forced shifts, those roll pins are bent. Bent roll pins will cause problems with the 2-3 shifts. Problems with the 1 shift is either a clutch or lubrication problems.

[Tillsy]

Chris, did you find a solution to this?

Whoops, I neglected to update this thread.

Yes, all good now. Not 100% fixed, on rare occasions I can 'feel' it's still not quite right but it absolutely does not crunch in any way.

All I did was change my transmission oil to a better one, and then flushed it again a few weeks later. Been a dream ever since.

So your next question will be what oil... I'll have to double check that tonight ;)

[kings1527]

Thanks Chris!

Thanks David T...great info there that I had no idea about. Interesting background that explains a lot.

[Tillsy]

Whoops, I neglected to update this thread.

Yes, all good now. Not 100% fixed, on rare occasions I can 'feel' it's still not quite right but it absolutely does not crunch in any way.

All I did was change my transmission oil to a better one, and then flushed it again a few weeks later. Been a dream ever since.

So your next question will be what oil... I'll have to double check that tonight ;)

80W-90 GL5 is what I filled with, twice to flush her out.