Cannot shift when cold.

[Jon Lane]

Searched, read, and have yet to find this issue dealt with. Simply, this car cannot shift into any gear but reverse when cold - pedal engagement point is at or below the floorboard. Car has a TRE trans with Amzoil 75-110 (this is Florida), new master and slave cylinders, a single flexible line between them, 20k on CC stage 2 ceramic clutch, and I've adjusted it by the usual methods.

When warm the car shifts completely normally - midpoint engagement, smooth gear changes.

It appears that I can only shift when in pump-up, although the clutch is at mid point and not at the top of it's travel when the car is warm so I'm not sure if it is pump-up. That is the only thing I've not yet tested. I've added travel by backing out the cruise switch as usual for these cars.

I believe I've bled the system well, but while I do not need instruction on how to do so, it may be possible I should bleed at the slave cylinder end, using the slave plunger. I'm doubtful this is it, however.

My question is if I assume there's nothing wrong with the hydraulics, what would be expanding sufficiently when warm to allow a car to shift then when it will not shift cold?

Again: I do not need advice on how to bleed anything; I'm asking what, if not the hydraulics, could cause a dimensional difference in the system that's temperature sensitive? On the other hand, if this is hydraulic, would air do this, and would I best remove it by bleeding the slave end of the line? I've bled the rest of the system four times, including with a vacuum pump. The line appears bled.

 

[Jon Lane]

FWIW, we're currently thinking this may be a cupped pressure plate that's thermally cycling to effectively change the thickness of the clutch disc between cold and warm states.

 

[TrevorS]

FWIW -- I replaced both cylinders, flushed, bled via pumping the clutch pedal and draining at the slave fitting, and have no clutch issues over my Delaware temp range. So, if your clutch actuator rod is adjusted properly and you bled properly then it must be something else.

 

[Jon Lane]

Unless it's air in the slave end, it's something else. Yesterday I confirmed that the master cylinder is adjusted just under pump-up, but cold the engagement point is under the floorboard. Very weird.

Local mechanic (who I do not trust) announced that the "clutch is collapsed". This despite it working fine when warm. It's possible, just not likely as far as I can tell.

 

[Mjrsplat]

I had this same issue just before my master cylinder went out, I'm in the process of getting the car back together now. any updates would be beneficial.

 

[Jon Lane]

Update: New master, new slave, about six bleeds, from vacuum to gravity to pedal. No difference.

Out comes the trans - as the only remaining component, it has to be the clutch, which is a CC Stage 2 that's never really felt right. I had a long talk with Jon at TRE and we're speculating that this could be a cupped pressure plate. Lots of clutches have insufficient mass to deal with heat before they deform.

That's conjecture but I've no other alternative but to yank everything and start inspecting and replacing things.

The DSM aftermarket I'm finding to be more and more incompetent as I go along.

 

[Mjrsplat]

Thanks for the update, it appears I'm pulling my trans to replace a clutch fork that's worn (shimming seems like a band aid fix to me) while I'm in there, I'll be sure to see what's going on with my pressure plate. I have an act 2900 so I'm not sure how common pressure plate issues are, but I'll check it out and post results within the week.

 

[Jon Lane]

I have an act 2900 so I'm not sure how common pressure plate issues are, but I'll check it out and post results within the week.

Act clutch failures.

 

[prdsmracer03]

Where are master and slave from?????? That's # 1 question I just had this issue a couple months back on my 2g. If your using advanced auto, autozone, pepboys BS then theres your main problem........I wish I had kept pictures of the difference between aftermarket and OEM masters because they were way different.

LJ

 

[Jon Lane]

Where are master and slave from?

Current slave is an Exedy, previous was OEM. (Exedy is a major Japanese OEM and I'm told had built ACT.) Current master is something from Rock Auto. Previous one was OEM. NO difference whatsoever in feel or function. Neither the OEM master or slave were leaking.

I wish I had kept pictures of the difference between aftermarket and OEM masters because they were way different.

In what ways?

I was only able to shift if I ran the master in pump-up mode and after warm-up. With the master adjusted correctly (just under pump-up) there's no way to get any clutch disengagement whatsoever.

 

[97gst_spyder]

Just so you know there is a big difference between OEM and aftermarket masters and slaves. Not saying thats the issue, because its not just some info.

http://www.dsmtuners.com/forums/dri...aftermarket-clutch-master-slave-cylinder.html

What fluid are you running in the trans? Ever drain some and check for shavings?

 

[Jon Lane]

Just so you know there is a big difference between OEM and aftermarket masters and slaves.

Thanks for the link - some excellent info in it. In all my reading I never saw it.

Now I'm reconsidering the master cylinder. What's weird, though, is the temperature dependency this system has. Heating the slave didn't do anything; I'm wondering if it's really possible that engine compartment air has to heat the master to get the system to have sufficient hydraulic "hardness".

Months ago when this first began, a long drive at speed would lower the engagement point toward the floor and I always assumed it was air in the line relaxing as the front of the car cooled. Driving around town would bring the pedal back up.

These symptoms may be consistent with a dished pp or some other major defect in the clutch that's also temperature dependent, so who knows...

What fluid are you running in the trans? Ever drain some and check for shavings?

Well, with the 2nd gear syncros gone now, it wouldn't surprise me but I'm not driving the car until the trans has gone back to TRE for that repair plus solving some major gear over-run noise since it was new. Also having the EVO 1st installed.

 

[Mjrsplat]

I believe my problem is due to an aftermarket master cylinder combined with a worn clutch fork. I'm going to replace the clutch fork and inspect my clutch/pp and go from there I guess.

 

[Jon Lane]

A new headache: The vertical clutch hanger - the piece the pedal is welded to - has let go somehow. I can't tell until it's taken apart, but it may have snapped or slipped right around the pivot point to the master cylinder input rod. The bottom moves more then the top of this arm and the master cylinder isn't being driven enough to disengage the clutch.

There's plenty of resistance to this movement around that point, and the pedal and bottom part of the pedal hanger haven't dropped off, so I'm hopeful something else just needs to be rebuilt, and that the whole darn arm hasn't failed.

I've never heard of this component breaking. Does anyone have experience with the pedal hanger? Is there a diagram of the assembly online? Does anyone know where to get parts for the 2G clutch pedal assembly.

This seems to be the perfect storm of all known 2g clutch issues now compounded by an under-the-dash trainwreck.

 

[97gst_spyder]

2g's normally dont ever break. Its the 1gs that do. Now when you get a replacement, make sure its from a turbo car. The NT 420 and 4g64 have a crappy petal assy.