This post is open for everyone, the more advice the better. Hopefully my good friend Amber from Six Speeds Inc. will chime in


The good:
3 weeks ago I bought a 2004 GTO. Lingenfelter sleeper cam, with an ATI Procharger DS-1SC. Some other goodies that I don't need to list, but it also has an RPS 2900# clutch and GMM Shifter. 540rwhp 11,800 miles. NEVER (remember this!) NEVER beaten on. It's been down the track 7 times from the previous owner, LIGHT passes....540hp and could only get a 13 second pass...so very light passes lol

This car was driven by the previous owner for gas mileage...i can't stress enough how babied this car has been.

Which leads me to the bad:
Drove the car 1.5 hours home, couple hours that day. Drives like a dream. After about a week, I notice that shifting from 1st to 2nd, it started to grind going in. It would go in just fine, not hard or anything, just came along with a grinding noise

My fix:
Bleed the clutch, the flood was cooked, black.

Fix didn't work, problem got worse and reverse started to get hard to get into. Looks like I ran into the common problem with GTO's of the slave going out

This weekend, I put in a new slave, stainless clutch hardlines (no more factory rubber section) and Wilwood high temp brake fluid. Bleed everything out, good to go.

Now the ugly: - Test drive (today)
went to back the car out of the garage, it went into reverse like a dream. SWEET had to pull back in, went into first, no problem....awesome!

started down the block, no issues from 1st to 2nd. staying under 3k rpm

moment of truth, back road, get above 3k rpms (boost is coming on)....GRINDS INTO 2ND! F*CK

so the problem has improved greatly but I still have the 1st to 2nd grind. Since my initial thought was the clutch wasn't disengaging fully, should I shim the slave? Or....have the syncros gone bad?

at first everything seems to point to the clutch not disengaging...now...i don't know


I know these MN12's and T56's are supposed to be so strong....and since this hasn't been beaten on....why would the syncros be bad???


I really can't afford to have a rebuilt trans....especially if it doesn't need it?



What do you guys think? I'm pissed that i might have to tear this down again....
bad clutch?
air in the lines?
trans?

 

Im in a same boat as you but worse, I put had my transmission rebuit, and its grinding going into 5th.. Im not 100 % sure of the cause though My slave and master is new, and the car doesnt move when you do the RPM test with the clutch pushed in..

 

You would still benefit from an adjustable master IMO.
But you may be looking into a trans overhaul in the future anyway

 

Amber and the SixSpeedsInc crew are in Joliet, IL for the races this weekend so not sure if she'll be checking the internet or not.

 

I'm sure the trans will need an overhaul eventually, but its REALLY been babied... 540hp or not

I've done some other checking around and people seem to think that the clutch is still not fully disengaging...since its only grinding at HIGHER rpm's, the increase from the pressue plate is causing it not to disengage 100%

I'm going to drive it a bit more, bleed it good again. If that doesn't do the trick I'm going to add a shim. I really don't think the syncros are bad yet.



For the adjustable master...how could that benefit (i really don't know)? The master on the GTO's looks like a PITA to pull. I'd like to try these other options (even the shim) first

 

Any other clutch sponsors out there want to chime in?

 

Is the fluid still clear? Does the car creep when you free rev it in the driveway in gear holding the clutch pedal down?

Regards,

Will Baty
Centerforce Clucthes

 

fluid is all clear, since i just put it in

free rev's just fine


maybe when i'm under load though, the slave just doesn't have enough throw to force that higher clamping force off...hence a shim?

 

Is the pedal stiff compared to stock & at what point does the car start moving when you let up on the clutch pedal (top or bottom)? Does it seem to get worse with heat (after you have been driving for a while) & does the car have headers? The heat from the exhaust has an effect on the fluid it changes the viscosity of the fluid and doesn’t work as well. Another question is what type of transmission fluid are you using we have seen some X brand miracle fluids do nothing but create release problems. Amber would be a better person to elaborate on this. There are so many things that cause release issues and most of the time the clutch is the first to blame but in most cases it tends to be something else. But you can always give Rob a call at RPS (818) 993-9174 he may have run into this before with his 2900# clutch? You may just need to change to an adjustable master to fix the problem if the pressure plate throw-out bearing load is too high? The stock hydraulics sorry to say are not that great…this is an issue for every aftermarket clutch company. So any and everything you can do to upgrade the stock hydraulics is a bonus. I hope this helps a little?

Let me know your findings,

Will Baty
Centerforce Clutches

 

Heat isn't an issue (anymore) since I just took it for a test drive yesterday and again today, and she has the Wilwood High Temp (600*F rated) fluid.

Today I noticed a new symptom...when taking off from first, like a normal person, you press in the clutch, and then put it into 1st. no problem

but I tried something else....lean the shifter over (so all I have to do is push it forward). I pressed in the clutch and then right away pushed it into first....it grinds!

So it seems like if I leave the clutch in and pause, I don't have any grinding issues....at all.

so again...clutch? master? trans?


Rob didn't have much to say other than try the hardlines or buy his $2400 twin disk (SCREW THAT). He did say the 2900#, that some of them have too heavy of a pressure plate and that they cause problems like this...maybe I have one.

Engagement...well it seems...normal. the throw on the GTO is SO much shorter than my Fbody, that it just seems right...I would say right in the middle'ish? or slightly lower

I'm not sure what the previous owner ran in the trans, but I just put Mobile 1 ATF in it.


totally lost and REALLY angry

 

talked with the previous owner, only 5-6k miles on the car

NOT hard on it

 

bump for fresh eyes

I don't know if the stock master can be made adjustable? its different than the Fbody

There is no adjustable made for this car yet...if I went with Tex, they only recommend stock hydraulics


so...clutch? trans?

 

Here's an idea, have you check the transmission fluid itself? Maybe its a little low? From what you said when you push the lever to the left and it grinds 1st it sounds like maybe a synchro is bad? Maybe bent shift fork?

 

refilled the transmission when i did the slave swap

I said about moving the shifter to the left, that way i would have a "quick shift" into first

 

took it for some more driving today
it seems to be engaging towards the top for sure

my questions is...if for some reason the clutch is going bad....are these symptoms?

I mean it ISN'T slipping, but could it be something else with the clutch?

I'm about ready to call up Textrilla and get one....so if your a Tex sponsor, chime in!!

 

Just got off the phone with Byunspeed about a Textrilla

They said to go with the Z Grip since it will NOT slip under boost


Think my current clutch is starting to do that? slip under boost?

this is just stupid...shes sometimes grinding going into first if I do it quickly....but I don't see how syncros could be BAD for 1st gear?! especially on a non abused car