View Full Version : Clutch slippage question

.Mad Hatter.
05-10-2012, 08:28 PM
Car: 2871R elim with 440cc tune.
Clutch: Southbend Stage 3 (good for 395ft. lbs)

I bought the clutch lightly used and re-surfaced my OEM flywheel. The disk has plenty of life left.

I broke it in accordingly (1000-1200+kms of city driving) and have not even done a launch. I did a pull tonight in 1st through 3rd and it slipped in all 3 gears at around 5k @ 21psi. I then drove home and pulled in 3rd to redline and it held.

The car sort of shutters if I start from a rolling stop. This all seems to mean a hot spot on the pressure plate I think. Any thoughts or experience? Is it possible I'm making more than 395ft. lbs @ the crank?


J Ozzie
05-10-2012, 09:25 PM
SB is bad!
Sounds like a piece of the clutch decided to stick to your FW! Ive had that happen like 3 times with my sb clutch and soon said fuck this! CM i went

05-10-2012, 09:27 PM
^^^^^^ CM FTW

05-10-2012, 10:17 PM
Shutter like as if you are FWD and your getting wheel hope?

Because that type of shutter is the disk skipping across the surface of the flywheel/PP because there isn't enough clamping load on the disk, this happens when the disk wears down and the clamping load decreases because there isn't as much pre-load once the disk has worn down past a point.

There can always be plenty of material on the disk, only a self adjusting clutch (SAC) will use all of the material because is it always adjusting to close the gap like a brake setup does.

395 lbs is the clutch rating at the clutch or basically at the crank. On a 1.8tq that is just 308 ft/lbs at the wheels. As you increase the load on the motor/driveline the higher the tq load gets at the clutch which means the clutch tq rating decreases.

.Mad Hatter.
05-11-2012, 06:07 AM
Correct Mike; it is similar to wheel hop but it seems isolated in the tranny...I also have a humming on cold startup which I am just now maybe associating with the clutch as it seems to have started around the same time.

I'm mostly curious how this would have happened. I allowed for proper break in, there were no visible hot spots prior to the install, etc. The issue only seems to happen under certain circumstances, which I obviously cannot pinpoint.

edit: pulled to redline again in 3rd...no slipping. I pulled (without launching) in 1st and it either bounced off the rev. limiter or slipped RIGHT at redline. Either way, I figure I'm making peak torque earlier in the powerband anyway so it was probably redline. I feel like if I can get it to start from a stop WITHOUT the stutter (don't feather, pretty much just let it out) that it will hold. A friend mentioned that sometimes if a hydro clutch is released too slow it will not grab at all. He also suggested I bleed the clutch (it has not been done in probably 3-4 years).