Clutch - ZR-1 Net Registry Forums

Demps · 06-19-2014

I'm not so sure I want to open the back-and-forth expert discussion but this may help some of us non-experts. I would like to offer my observations on installing two different clutches in the same car.

The car: '91 SGC 350 with 400rwhp thru B&B with pup cats and x-pipe. Car is my HPDE car. It has a Fidanza, Hurst short shifter, RC injectors and a lot of other mods not pertinent to this discussion.

Initial problem: clutch went out at VIR.

Diagnosis: throw out bearing failure or disk material separation. The car had mostly sat for ~2 years prior.

1st solution: Carolina clutch stage 2 with LT1/4 pressure plate and "green" throw out bearing.
Result: a very grabby clutch that shuddered moderately on progressive take up/let-out AND action at the very top (top inch) of the clutch pedal. The sprung hub disk dampened most gear rattle at idle and under a bogged load (gear-high acceleration). The clutch held up fine on road course. Clamping force was always suspect. It finally slipped on the drag strip at BG to the point it was done.

2nd solution: back to stock Valeo disk and LT5 pressure plate with US throw out bearing.
Result: a stock clutch and accompanying feel--smooth progressive engagement/release at bottom of pedal travel. The solid disk allows light gear rattle at idle and moderate whine under bogged load. Still breaking clutch in so assumption of stock clutch performance will hopefully be validated with time.

Observations: stage 2 disk nominal thickness at take out was 0.285. Valeo was 0.305 at installation. The diaphragm spring and material in LT5 PP had more to it--while I didn't measure it, Jim Jandik (PowerTorque) referenced +10% and in my setup I'd say he is conservative. I was moving quickly so I eye-balled the stage 2 disk on LT1/4 PP--about 1/3-1/4 of disk material outside of PP mounts. Valeo & LT5 PP--over 1/2 of disk thickness outside PP mounts.

Conclusions: stage 2 disk may be a good option for some but it let me down in my application. It was difficult to control engine revs on road course with release at top of pedal. There is a critically small margin of travel between flywheel and PP. If quality control is good, I think the stage 2 disk & LT5 PP would be a good option for performance applications. I think RAM is next. I am very pleased in going back to stock setup.

Ted

06-19-2014	#1
Demps Join Date: Jan 2006 Location: Niceville Posts: 998	Clutch I'm not so sure I want to open the back-and-forth expert discussion but this may help some of us non-experts. I would like to offer my observations on installing two different clutches in the same car. The car: '91 SGC 350 with 400rwhp thru B&B with pup cats and x-pipe. Car is my HPDE car. It has a Fidanza, Hurst short shifter, RC injectors and a lot of other mods not pertinent to this discussion. Initial problem: clutch went out at VIR. Diagnosis: throw out bearing failure or disk material separation. The car had mostly sat for ~2 years prior. 1st solution: Carolina clutch stage 2 with LT1/4 pressure plate and "green" throw out bearing. Result: a very grabby clutch that shuddered moderately on progressive take up/let-out AND action at the very top (top inch) of the clutch pedal. The sprung hub disk dampened most gear rattle at idle and under a bogged load (gear-high acceleration). The clutch held up fine on road course. Clamping force was always suspect. It finally slipped on the drag strip at BG to the point it was done. 2nd solution: back to stock Valeo disk and LT5 pressure plate with US throw out bearing. Result: a stock clutch and accompanying feel--smooth progressive engagement/release at bottom of pedal travel. The solid disk allows light gear rattle at idle and moderate whine under bogged load. Still breaking clutch in so assumption of stock clutch performance will hopefully be validated with time. Observations: stage 2 disk nominal thickness at take out was 0.285. Valeo was 0.305 at installation. The diaphragm spring and material in LT5 PP had more to it--while I didn't measure it, Jim Jandik (PowerTorque) referenced +10% and in my setup I'd say he is conservative. I was moving quickly so I eye-balled the stage 2 disk on LT1/4 PP--about 1/3-1/4 of disk material outside of PP mounts. Valeo & LT5 PP--over 1/2 of disk thickness outside PP mounts. Conclusions: stage 2 disk may be a good option for some but it let me down in my application. It was difficult to control engine revs on road course with release at top of pedal. There is a critically small margin of travel between flywheel and PP. If quality control is good, I think the stage 2 disk & LT5 PP would be a good option for performance applications. I think RAM is next. I am very pleased in going back to stock setup. Ted