I did some searching and still have questions.

the car:
2005 GTO (~50K miles)
aps tt putting out 660/680

the transmisson:
stock T56
OZ700SB w/steel billet flywheel (~10K)
stainless steel hydraulic line
throw out bearing replaced when clutch was changed.

problem:
on the street (with street tires) the car runs fine, no issues at all. I can gradually run 3rd gear to wot without slipping and shift quickly to fourth with no problems.

However, at the track with drag wheels and slicks, it's a different story. Yesterday at the track when I tried shifting 1-2 the car would come out of gear, but would not go into the next until the rpms dropped a little (6500 shift point). Right after that run we bled the clutch completely and put new fluid in (valvoline synthetic). Next run I made the 1-2 shift, but the 2-3 shift was no good as well as the 3-4 shift.

The clutch does not slip at all! i was able to cut a 1.54 60' launching at 4500 under 3psi (race weight 3970). At no point in time does the clutch slip, street or strip. Also, never at any time do I lose pedal firmness!

Another thread advised the clutch could be dragging and said put the car in first, clutch pedal to the floor and rev the car and see if it creeps. well i've done that on several occasions and it does not. At the tree it doesn't creep.

I don't think it's the clutch because other people are having these issues with different clutches. I don't think it's the throw out bearing or master cylinder because it's only happening at the track and not all the time. But at the same time I don't think it's the transmisson because of the same reason, it only happens at the track.

Here's another thread with the same issue:
https://ls1tech.com/forums/showthrea...=670847&page=3

specifically this post!:
http://https://ls1tech.com/forums/sh...4&postcount=48

So please do not say, change the master cylinder or bleed the clutch!

At the flywheel the car is putting out ~759/782, is this too much for the T56?

I need some help. What is it?

Thank you!

 

I had a simular issue kinda. I was powering thru the clutch I found only at the track w/ the slicks. I attributed it to the clutch must have been getting hot.
But anyway I found that my shift light was the tell tale. it would come on early, or on then off again in the run.

You might be simply having heat issues with the fluid.Wrapping the braided line to sheild it from heat is also a good idea. I would also highly suggest flushing the clutch master's fluid out by bleeding. I know it helps me curb alot of problems. I maintain mine regularly , once it gets a little dark it's flush time.
Another big thing IMO is an adjustable master cylinder. The ability to adjust out the excess freeplay helped me tons in the powershifting dept.
I usually leave with a 2 step 5500+ & never lift of the gas pedal till the finish line.

I would suggest trying to do the easy stuff first & see if you can tune the pedal/clutch release to the optimumn before going into another clutch replacement.

 

I don't know if I can blame it on the clutch getting hot, the very first run was with the car coming right off of the trailer and running at operating temperature. the second (after the bleeding) was easily 30minutes later.

I already bought some heat shield tubing for the braided line. I always thought the clutch line ran very close to the turbos, but after some more inspectiong I saw that it really doesn't. This doesn't mean I will not wrap it. Also, like I said above, after the first run I changed out the fluid and it seemed to clear up the 1-2 shift (although it was still harder than it should have been to shift).
Also, when you talk about free play in the master cylinder, are you talking about the pedal being having no force feedback till you push it a goodways? My pedal is firm all the way to the floor.

I understand about doing the easy stuff first, I'm just not convinced it's the master cylinder

Thank you for your feedback!

 

Yes if there is a little play or no real fluid compression that is free play.
If you have the ability to adjust that out it will make the clutch come off sooner.
The pedal will move fluid sooner w/ the same stroke.
That really helps High RPM shifts.

My car sarted to get hard to shift when the clutch slipped, it must have been the heat + the fluid really took a beating & got dark much quicker.
I knew I had an issue then.

 

so i'll eat my words and cry in misery!

clutch = shot.
tranny = fine.

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I already bought a stage V tranny from RPM. That's why everything is out. Even though it looks like the clutch is the problem; I'm willing to bet money that after I get something stronger that the stock tranny will show its ugly head and fail.

Question now is, which clutch to go with?

 

by the looks of that flywheel that thing was red hot, may have a bad slave that caused it

 

I would go with a twin disc IMO. I did, love it no more problems in the clutch department!

 

slave was changed with the clutch, although i wont rule that out. i remember one time in particular that i burned the clutch at the track trying to launch a different way. could have caused the "glowing flywheel"

that's what i'm thinking i'm going to have to go with...which one did you get?

 

i know my flywheel had color spots in it and so did the clutch disc when i changed mine but it was because my slave went bad and did not lit the clutch fully engage

 

did you have problems with it all the time? mine only happened at the track.