Determining clutch engagement issue?
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,823
Likes: 43
From: East Aurora NY
Determining clutch engagement issue?
Long story short, I lost reverse in my RPM built M12 trans. I called RPM to get a cost estimate to fix the transmission and it was brought up that the symptoms I am seeing usually are caused by clutch engagement issues. I don't want to rebuild the trans, and have it happen all over again, so how does one determine if they are having clutch engagement issues (even very mild issues)? I am running a Mantic 9000, tick master, remote bleeder.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Car on flat level road. Start the engine. Put the trans in 1st, clutch fully depressed. REV the engine to about 5500 rpm with the clutch depressed.
If the car creeps forward at all,, the clutch is not fully disengaging from the flywheel and or pressure plate.
I also jack the rear wheels off the ground. Car in gear and clutch fully depressed. If you can hold the rear tires from rotating by hand,,, the clutch is still driving the prop shaft. This is how I adjusted my TICK Master Cyl. I would give the adjust rod a 1/4 turn at a time until the wheels no longer were driving.
NOTE! You may have some minor rear wheel rotation even with it perfectly adjusted. BUT,,,,,, You should easily be able to stop it by hand.
Once I have it adjusted so its not driving the wheels with the clutch fully depressed, I find out the exact point where it engages by slowly letting out the clutch. That allows you to add a little or remove a little to put that point where you want it.
I've see C5 that have a VERY difficult time getting the wheels from driving. Each time it was the result of NOT having the correct slave cylinder shim depth. Not enough shim and you will not be able to add enough adjustment to be able to push slave piston out far enough to fully compress the pressure plate springs and release the disk.
On the other side of the coin,, Too much shim and the pressure plate springs will always be riding on the throwout bearing with enough engagement to cause the clutch to slip under power. That's when you burn up brand new clutches and throw out bearings.
Bill
If the car creeps forward at all,, the clutch is not fully disengaging from the flywheel and or pressure plate.
I also jack the rear wheels off the ground. Car in gear and clutch fully depressed. If you can hold the rear tires from rotating by hand,,, the clutch is still driving the prop shaft. This is how I adjusted my TICK Master Cyl. I would give the adjust rod a 1/4 turn at a time until the wheels no longer were driving.
NOTE! You may have some minor rear wheel rotation even with it perfectly adjusted. BUT,,,,,, You should easily be able to stop it by hand.
Once I have it adjusted so its not driving the wheels with the clutch fully depressed, I find out the exact point where it engages by slowly letting out the clutch. That allows you to add a little or remove a little to put that point where you want it.
I've see C5 that have a VERY difficult time getting the wheels from driving. Each time it was the result of NOT having the correct slave cylinder shim depth. Not enough shim and you will not be able to add enough adjustment to be able to push slave piston out far enough to fully compress the pressure plate springs and release the disk.
On the other side of the coin,, Too much shim and the pressure plate springs will always be riding on the throwout bearing with enough engagement to cause the clutch to slip under power. That's when you burn up brand new clutches and throw out bearings.
Bill
