70 "S" Clutch Dilemma

[Cornpanzer]

Well.....I am officially out of money!
Getting the "S" ready for the trip out to Sonoma this spring. Along with a long list of maintenance and upgrades, I decided to pull the engine/trans to deal with some MFI oil leaks. My mechanic buddy convinced me that "While you are in there" I should seperate the engine and trans and check the clutch. Now I have never had any clutch issues, but wise advice. The clutch isnt terrible, but it is getting pretty thin.

My problem now is that I simply dont have the money to buy a new pressure plate, throwout bearing and disc. I have dropped about $3500 this winter on the car and I am tapped out.

If i pop a new disc in and leave everything eles alone will the Porsche gods seek retribution for my sins somewhere halfway between Ohio and Sonoma? Keep in mind that the car is generally well maintained and the clutch exam was more curiosity than anything else.

Comments and opinions?

[Cornpanzer]

As a side note, the presure plate is aluminum. Is that a factory piece on a 70S?

[afterburn 549]

I would not hesitate to drop a new one in and leave all else alone. In fact I had my curent one rebuilt (45.00) Been two years of flogging (10,000 miles) and my trans axle is moaning but the clutch dept is holding. I know the purest will have a finger rachting report on their key board here over this ,but I just say what works for me- might work for you. Whats the worst that can go wrong ?? save a bundle or pull it again and spend a bundle..i will take the 1st choice as my labor is ezr then $$

[DByers]

I recently replaced the clutch in my 71. I only replaced the clutch. PP, flywheel and TO bearing were fine. Its been 500 + miles with no issues. My .02 is that you will be fine. A PM to Grady would not hurt to ease your mind though. Maybe he will chime in.
Do you know if and when the other parts (PP, flywheel & TO) have ever been replaced?

[silverc4s]

Originally posted by Cornpanzer
Well.....I am officially out of money!
Getting the "S" ready for the trip out to Sonoma this spring. Along with a long list of maintenance and upgrades, I decided to pull the engine/trans to deal with some MFI oil leaks. My mechanic buddy convinced me that "While you are in there" I should seperate the engine and trans and check the clutch. Now I have never had any clutch issues, but wise advice. The clutch isnt terrible, but it is getting pretty thin.

My problem now is that I simply dont have the money to buy a new pressure plate, throwout bearing and disc. I have dropped about $3500 this winter on the car and I am tapped out.

If i pop a new disc in and leave everything eles alone will the Porsche gods seek retribution for my sins somewhere halfway between Ohio and Sonoma? Keep in mind that the car is generally well maintained and the clutch exam was more curiosity than anything else.

Comments and opinions?

My 70 S clutch is aluminum also, I think they all were, but Grady or another expert will confirm, I'm sure.
I would not hesitate to reuse the PP & flywheel if they are within spec. A new TO bearing might be good peace of mind insurance though...

[Grady Clay]

Sorry for missing this thread. Too often when I have to deal with the docs something escapes. Thanks to the Pelican who e-mailed me.

The ’70-’71 225 mm clutches were originally all (T, E & S) aluminum clutch pressure plates (PP) as I remember. By ’72 some (most?) had iron moving pressure piece. In ’78 we saw the first all iron clutch pressure plates on the 911SC.

So what is an aluminum PP?

The outer housing is aluminum with 9 steel bolts attaching it to the cast steel flywheel. The diaphragm spring is (naturally) spring steel. There is a steel wire ring for the diaphragm spring to pivot on. There are three leaf springs and hardware that act to transmit driving torque and keep the moving pressure piece concentric. The “trick” part is the moving pressure piece is aluminum with flame sprayed steel facing for the friction surface.

Can someone post the link to the Sach site? I’ll bet there is much info there.

If everything else is OK, I wouldn’t hesitate to just replace the disc.

The other things are to carefully inspect the PP for cracks, damaged leaf springs & mounts, eccentric moving pressure piece or a broken diaphragm spring. A daub of moly grease in the pilot bearing is necessary and clean everything. You need to confirm the clutch release arm pivot update and lube those parts.

It is very subjective but feel the clutch release bearing. Do not clean the bearing in solvent or anything – it isn’t a sealed bearing. Wipe the bore and apply a little molly grease. Clean and inspect the outside of the guide tube and apply a little molly grease.

At Rennenhaus we would always replace the engine flywheel seal, the transmission input shaft seal, install the “dam seal” mod and replace all the hardware.

Clean the transmission input shaft splines and inspect the pilot bearing running surface. Take the new disc and test fit it to the transmission input shaft splines. Apply a miniscule amount of moly grease to the splines and run the disc axially back and forth, repositioning occasionally. Wipe off any excess grease. You will ruin your new disc if you leave any grease that can get spun onto the friction surfaces. You can hose off the PP & flywheel with WD-40 and wipe/blow off the excess.

The last thing to do before assembly is to wipe the steel friction surfaces of the PP and flywheel with brake clean. When tightening the PP to the flywheel, go very slowly and evenly to not bend the PP. I’m sure this is what causes cracked PPs and broken diaphragm springs.

Don’t forget to reinstall the starter ring gear.

I have done several detailed posts on this subject, do a search and post links.

Best,
Grady