yahh

Hey guys
I've been having some trouble with my T56 M12 (GTO TRANS) after rebuilding the motor. I'm getting gear lockout at high RPM but only when loaded. I can neutral rev to 6k and shift into gear fine, but when I try to go gear to gear it locks me out. I have also noticed that I have gotten some fluid coming out of the breather hose on the trans when at redline and trying to shift. I have about 6k miles on this setup and this is the second or third time i've had it on or off and have never had these problems before. Any ideas?


M12 Trans
LS2 Flywheel
LS7 Clutch
F-Body B&M Short Shifter

I've tried re-bleeding the clutch and there is absolutely no air in there and I have removed the reverse switch to check to check the fluid. The trans was slightly over filled so I let it drain until it stopped coming out of the reverse switch.
Thanks!

Guitar

iTrader: (9)

Could be that you need a Tick Master (or do the drill mod). Another issue could be the pressure plate, which turned out to be my issue and replacing the clutch/PP fixed it for me.

yahh

Forgot to say that this is swapped into a 1995 BMW M3.

murphinator

iTrader: (2)

how did I know it had an LS7 clutch before opening thread.... because I have one and same issue too heavy for hydraulics ( heavier than ls1/ls6 clutch) and self adjusting pressure plate to boot.

Guitar

iTrader: (9)

Must have been the problem with mine, I had that clutch before I put in the Monster Stage 3.

Albertan

I've had the same problem. Mine is in a 97 318i! Spec twin disk clutch. I replaced it with another Spec clutch. I put in a Tilton 7/8" dia master. Still can't pull it out of gear at anything over 5000 rpm. If I keep the engine at 5000, then it come out just fine. It seems to not release the clutch disks. At 4000 or less it shifts very nice. Driving me crazy.

ranmas2004

iTrader: (1)

Anyone ever figure out an answer to this? I have a Nissan 300zx LS7 swapped. Using Katech LS9x Clutch kit and it does the EXACT same thing to me above 5000 rpms lockout....down low shifts OK a little notchy.

HioSSilver

iTrader: (8)

Yea.....**** pressure plates. Put a good clutch in it and stay away from that heavy ****.

JD_AMG

What master cylinder are you using?

2011grandsport

Master cylinder does make a difference.(Need Tick adjustable). I ran into with the same situation of not wanting to shift at high rpm's, this was tolerance stacking or better yet the lack of having any tolerance in the clutch set-up. I do not have the ls7 clutch but i did have a monster level 3 and found that there were no tolerances, everything was too tight. The optimal is approximately .125" or 1/8". I also learned by checking the slave cylinder and finding that they are not all created equal. I tried to use one purchased at the local parts store and it looked identical to and was supposed to be the gm slave, wrong. It appears to be and has all the numbers to match but when i purchased my next slave i went to tick along with getting their master cylinder and speed bleeder. Upon receiving the new parts i compared them to the old and the slave from tick had 1" overall travel verses 3/4" on the local part store version. Now to the tolerance, once clutch was installed and bell housing i checked the distance to the fingers from the face of the bell housing and then checked the slave on the trans. Had approximately .250" tolerance so had to add shim behind slave putting it within the range required. Installed trans and bled with speed bleeder, drove for approximately 585 miles before high rpm launches at the track and she worked flawlessly at 6500 rpm shifts. My best guess is with no or too little tolerance in the set up the slave cannot over come the inertia created by the spinning of the clutch by having too much g-force against it, result will not release the clutch enough to shift.