3.6 conversion gurus, question about heavy pressure plate

[Jim2]

I've just bought a really nicely restored 1977 SC that has a 3.6 engine conversion. For some reason the PO installed a racing pressure plate (and a very light Patrick Motorsports flywheel). It takes so much effort to disengage the clutch I actually bent the clutch pedal during the 300 mile drive home. I suspect the PO had similar problems though he never divulged this. After straightening the pedal I wanted to make a minor adjustment to remove some play but I found the threaded cable sheath at the transaxle was at it's end of adjustment, leading me to believe that the clutch cable has stretched. Further to this I noticed that the pedal box flexes when I push the clutch in.

Besides the excessive pedal effort needed, the clutch seems to work fine. This is a stock 964 motor so there is no need for this monster pressure plate. If I run the existing pressure plate I'll have to reinforce the pedal arm and likely replace the cable as well.

Should I be concerned about the cable, thrust bearing, and pedal box etc and proceed with a replacement pressure plate, or am I worried about nothing?

(PS next I need to change out the torsion bars which are waaaaaaay to stiff! 23/32 for the street!!!)

[shbop]

bump for some more opinions. I'd sure like to know what caused the stiff pedal. Have you yanked the pedal cluster and checked the bushings and other related clutch actuating parts?

[Jack Olsen]

Is the omega-shaped helper spring present on the underside of the transaxle case?

[ischmitz]

Something is wrong. I would start by looking at the clutch cable itself. Maybe it is kinked or dirty resulting in what you observe. Also the bushings. I have not heard of a pressure plate that take so much effort that you bend the clutch pedal.

And you are rigth in that a 3.6 doesn't require a racing on/off clutch. It only stresses components. Get a regular Sachs clutch. We trashed a T1 VW motor in 1000 miles with a Kenedy racing clutch. The thrust bearing was ovaled out and resulted in lost oil pressure. Plus the car was a pain to drive with that clutch. After putting a milder clutch in it improved driveability like night and day.

On the torsion bars I would hold off and check what type of shocks you have installed. I have a similar combo of torsion bars in my Targa and couldn't be happier. Maybe get a adjustable Koni's so you can soften the ride for the street.

Cheers,
Ingo

[Jim2]

Thanks for the feedback guys.

Jon, I've inspected the clutch pedal shaft for play and I can't detect any slop. The dirt around the pedal assembly is residual media from when the car was soda blasted. I've cleaned around it, lubed the pedal shaft as best I could. When you wiggle the pedal it seems to move freely, but I'm unsure of the codnition of the cable.

Jack, the omega spring is in place. The only visible item missing is the backlash spring for the clutch lever, though this won't influence pedal effort. The pedal lever moves freely and has 1mm of clearance to the adjusting bolt. The pedal does have the usual over-center feel, just the effort of a racing clutch.

Ingo, I can't tell at this point what the condition the cable is on the inside. I'll take it out and have a look. I too have seen damaged thrust bearings from "racing clutches" back when I was a kid and running them on the street. This is exactly what scares me here, this is a driver and I don't want to bugger it up. Aparently it's had this clutch in place for 10K miles though. It justs seems like overkill to have a racing clutch on a driver.

The car actually does have adjustable Konis, but where I live the roads aren't the best. Highways are fine, but it's the city here where it's a problem.

When you say "get a regular clutch" would I order a stock SC/915 cast iron pressure plate 915-116-001-27-M38? My friend quoted a "sport clutch" which he said is aluminum pn 88-3082-746-M38 for about 3x price.

[ischmitz]

Hm, I have the sports clutch from Sachs with the Al pressure plate. It was something around 600$ for the complete package and I am very happy with it. On the other hand with the light flywheel a heavier iron pressure plate might be a good thing if the cost delta is that significant.

Ingo

[Jim2]

Hi all, here is an update. I've stripped the pedal box and restored the clutch pedal. The nylon bushings in the pedal box displayed some wear on the clutch pedal but I'd say less than .030". I've cleaned it up and rebushed it. Also bought a new clutch cable.

Today I removed the clutch and though nothing jumped out I noticed that the pressure plate has remnants of orange paint very much like the Patrick Motorsports centerforce clutches. I also discovered that the disk is a centerforce dual friction disk, exactly like those which Patrick sells.

The clutch actuation shaft in the bell housing requires a bit of force to move so I suspect it needs lubricating.

I'm unable to find any model references to this pressure plate on Pelican or the internet, so in light of finding no other issues I can only guess this is the racing clutch from hell. Unless someone has any better suggestions I'm going to proceed and order a regular 915 pressure plate tomorrow.

The disk measures 0.305". I believe it should be .330-.350 new so I'll assume I can get more life from this one, unless you guys say otherwise. The whole clutch (and engine package) only has 11K miles on it.

[ischmitz]

"F&S" stands for "Fichtel & Sachs" for what it's worth....

[Jim2]

I take it then that the pressure plate is not an aftermarket unit (like Centerforce) but rather a heavy duty replacement from Sachs?

You have any insight on the part number?