Lost Clutch today

[KGTM]

Hi All,

was driving the car today and noticed lots of clutch free play and stop shifting, long story short got home by pushing the car home with some help ( was not far from home), once car cold off the play got less a could drive it so I can get it driveway to garage.

what do you guys thing is wrong? Master or slave or air in line...

Everything was fine before small play as it should, reservoir is full to top slightly above limit.

Thanks,
Mostafa

[cob427sc]

Could be the small pin that acts as the pivot point on the fork. Mine fell out at one point.

[cob427sc]

This pin is accessible, not easily from the outside of the bell housing so you shouldn't have to split the engine/transmission to repair.

[KGTM]

Now that it has cool down it sort works just has more play than before but good enough to put it gear and move it, so if pin was out would it work at all?

could there still be some air in lines and expands when it was hot and cause more play?

Could cylinder be bad?

Mostafa

Mostafa

[VRaptor SpeedWorks, LLC]

My guess is air in the lines or slave......or the lines run too close to the exhaust and the fluid is boiling in the lines.

[KGTM]

I am very confused by this,

1. if the seals are bad then why just more free play and still applies good pressure?
2. if air in line then why free play is much more that before? I check all connections, they are look good.

I just want to make sure I fix the problem.

Thanks,
Mostafa

[VRaptor SpeedWorks, LLC]

What transaxle do you have?...G50 or Mendy?

[KGTM]

G50-20.

I think the only thing that make sense is very old fluid, looks like Dot 4 boiling temp will drop to almost to half over 6 years, I think mine been there for over 8 years. and may be boiling increase the vapor in the line.

What is funny I have noticed my clutch be much darker then the brake, and my be the combination of extra heat affects it.

what do you all use ? there seem to be high temp versions.

Mostafa

[VRaptor SpeedWorks, LLC]

Every single GTM we've had in the shop over the years (32 of them) is the same way with the clutch fluid. The brake reservoirs stay clear while the clutch fluid turns black almost immediately. Why....I'm not sure?

The "free play" that you're talking about.....that is just the "feel" in the clutch pedal? If so, I'd still guess that my #5 post is a good guess. The other (much worse) possibility is that you've broken off one of the clutch fork pivot ears inside the bellhousing......but I would guess at that point you would not be able to disengage the clutch at all.

[KGTM]

The free play as I called it is just how to adjust the clutch and master cylinder so that it does no always push in clutch once release, and may be there was some air in there but still worked as it was not much.

Also noticed over time my levels a bit higher but no really sure since have not look at it for a long time.

The clutch works now and actually drove it in forward and reverse, so I think is not the fork:)

I will try to bleed and is that worked, I will change to Dot 4 supper had much better temperature range. what od you use for fluid?

Thanks,
Mostafa


Mostafa

[VRaptor SpeedWorks, LLC]

I generally just use Dot 3 brake fluid unless the customer provides or specs out something else. If all of your clutch lines are routed away from the exhaust, the clutch fluid should not really be subjected to boiling temps or anything close to boiling.

[KGTM]

There is one area it is close, but do not see with car moving how it will get hot, possible if stopped but still not sure, will try to bleed it and see.

when I push the paddle the first %40 the slave move only a bit and after that moves ok, so must be air.

if that will fix it will add protection in that area and change to better DOT 4 fluid.

Thanks,
Mostafa

[crash]

Here is what we use in the FFR PDG GTM race car...

https://www.summitracing.com/parts/mtl-101667?rrec=true

Reasonably priced(compared to other racing brake fluids) and the WET boiling point is very high. If you can get your clutch fluid to 400 degrees...well, you have some sort of serious problem.

If you want to save a few bucks, here is what we used to use...

https://www.summitracing.com/oh/parts/mtl-100949?kr=rbf600

The wet boiling point is almost identical.

[KGTM]

I looked at these also they look really good, the ATE200 was a bit cheaper but only few degrees less, should be better than what I have ,I am also going to wrap with aluminum backed foil so combo hopefully will be good.

How close to exhaust is too close? there are areas that can not be far from exhaust , specially on the right.

Mostafa

[crash]

I don't know if you have looked at Shane's cable retention system?

My estimation would be that if they are within two finger widths, then that is too close. Of course a lot has to do with direction as well. Four finger widths would be WAY too close if the cables go above the exhaust, and two fingers should be plenty if under the exhaust with some shielding. Airflow also has a lot to do with it. Again, see Shane's products.

We have found that the aluminum backed products "are not optimal". Although the DEI products are very good with the fiberglass liners. Far better off with a thin shield of 304 stainless steel and an insulated product like the DEI stick on gold stuff with ceramic mat.

[KGTM]

Thanks Crash, for most part it is about 4 or son expect few short places, I have loom around the area and do not see much effect on them as they are lower temp than the oil should be, there is a very short area that was close may be an inch or so, so will add something, I have some DEI foils the ceramic backing, hard to add in and plates at this time, but I think the combination for wrapping foil and Oil type change should help.

Thanks for help.
Mostafa

[RR46]

What Shane and Crash said.
Air, poor fluid. Issue presents itself significantly first time over a certain temp.
Almost every race weekend and definitely every time we had the trans iut, I return from first practice session and ask team for rebleed of clutch. We use great fluid as outlined by Crash and car is bled well, still there is a miniscule difference in total compressibility one heat cycle in. Fix it = bleed, or eat syncros, or dogs on a racing transaxle.

Not unique to GTM, had this on Pcars too. I found Endless RF650 to be good as well, particularly good at keeping clutch consistent at extreme temps.

[KGTM]

All my oils where also old so I changed all brake and clutch with Motul 600, now clutch feels same as before, if happens again I will rebleed as you are suggesting, no need to change fluid this time.

Thanks.