Almost certainly. So far, however, circumstantial evidence only.
Done that (see first post).

I can't think how a fork failure would result in the clutch being permanently disengaged -- can you? Doc has shown an example of a disk failure that seems consistent with these symptoms, though.

I'll certainly check that once I've got everything apart, but there hasn't been any noticeable bearing noise. Last time I checked play (clutch job last year) it seemed fine.

 

Mark,

I installed the Vertex Power Friction disc on my '87----I checked on Vertex and if I did it correctly for your S2, the disc should be the same.

I have had no issues for 2 years and recommend the Vertex disc.
The friction material is Raybestos, and comparing the "thickness" to OEM spec, the Vertex disc is slightly thicker than spec.

I have attached a couple of pics. note the Vertex continuous band that is riveted to the inner spring plate. Compared to the Sachs with multiple 2 rivet attachments.

 

Thanks for that recommendation and info, John.

I got up to removing the transaxle today, so tomorrow I should get to the clutch, and find out what's what.

I'll post pics if anything interesting enough to warrant.

 

Be careful with aftermarket clutches.
They frequently require more force to operate than the stock equipment and, in the long term, this will effect the engine's thrust bearing, wearing it out.

 

Presumably this concern is only for set-ups with a stronger clamping force on the PP? An aftermarket clutch using only the stock PP (such as the Vertex) couldn't cause any additional wear on the thrust bearing, could it?

 

Well Doc, when you're right, you're right (see attached photo at end):

Question is: What do I order as a replacement? Chris White has suggested that a "whippy" torque tube that doesn't exhibit other symptoms may be the underlying cause, but I think it would be premature to replace the torque tube at this stage. A bit more evidence required for that. Like another clutch disk or two.

I'm inclined to try an aftermarket clutch disk next. Something robust, but not too expensive (in case the next one also decides to self-destruct in the near future.)

Another candidate is this one from ClutchNet:



It looks a bit beefier compared to the Sach units regarding the ring attachment to the hub (which actually strikes me as a bit flimsy once you see where it's broken). This ClutchNet disk is the organic lining model SM7281, which sell for $149 (even less expensive than the Vertex for $199.)

Any thoughts on the ClutchNet disks generally?

 

I would ask to make sure it works with the stock pressure plate, but if they say yes, then give it a shot. That looks like a much better solution than the sachs disc.

 

Do you ever want your wife to drive the S2 alone again?

I doubt if it was her driving that caused the problem. Unless you loan your car to the neighborhood teen devil ----it was your fault. I do not mean you do rear rolling "J" burnouts for the car shows, I mean whatever you do now will cause your wife to either drive the car again or be afraid of the next breakdown.

Here is the clutch diagnosis from Centerforce.
The only part that stood out similiar to your (probable) disc damage is "too much power for the disc".
Another reason is that the FW and PP were out of balance and the vibration caused the disc damage due to vibration.
Take a look.
http://media.centerforce.com/DiagGui...cGuide04DL.pdf

I know that PorscheDoc can change a disc with air tools and a lift in 10 hours or less and have lunch inbetween.
You will take a minimum of a weekend and possibly more if the FW got scarred with bits of the disc.

You have to consider if spending an extra $50 or $100 on a disc is worth it.

I have not used a Clutchnet disc. Old reviews on the net are mixed. I had trouble with the Clutchnet.com site. They are based in CA and there may be local info on other forums.

Clutchnet has to cut corners somewhere. It could be the tensile strength of the metal or rivets to the friction material.

GL
John

 

ROFL, that's insulting. My record is 3:50 on an S2. A tick under 5 hours on jackstands. And air tools are a thing of the past....electric baby!

 

I know and she knows it wasn't anything she did. It was just unlucky she was driving when it decided to let go. Of course, there is some teasing value in this, but she knows full well the metal fatigue would have happened during track driving.

Interesting read, although I couldn't see anything that really comes close to the disk failure I've experienced here. Certainly no symptoms of noise or imbalance anywhere. Clutch was very smooth and well behaved, in fact -- right up until it decided to let go. Even then it did so without much fuss -- I was surprised how quiet the whole failure was. Not a peep before, during, or after!

FW looks fine. This disk broke cleanly into just two parts -- inner and outer.

As I say, there was no grinding (or noise of any kind) indicating a metal-on-metal problem.


What sort of trouble? Technical website problems, or sales/service type problems?

I don't know. To me, it's not such a mystery how a company can "only" charge $149 for a clutch disk. It's much more of a mystery why they should charge $300+! (as in the price of the OE units.)

In any case, I've got the clutch disk out today, so the diagnosis is now confirmed, but now I've got to wait for 1-2 weeks for an new disk to arrive. So most of time is actually going to be spent waiting for international shipping from the US. The clutch job itself is not so much of a big deal for me -- I typically work for a few hours at a time, rather than all day, and for the most part I find it enjoyable. (I really don't mind working on the 944, and working at a fairly relaxed pace makes it more enjoyable, I find.) Day 1 -- remove the exhaust. Day 2 -- drop the transaxle. Day 3 -- remove pressure plate. (That's where I am up to now.)

Days 4-18 -- do other jobs (such as getting the seat upholstery redone) while waiting for clutch disk to arrive from US.

Days 19-21 -- put it all back together.

No, it's not a daily driver. :-)

My feeling at this stage is that the standard 944 spring centered clutch disk may be a bit marginal for the S2. To tell you the truth, I've always found it a bit surprising that they upgraded just about everything else to turbo spec for the S2 in order to handle the extra power and torque, but left the clutch at the original 2.5L 944 spec. A weak link, but one that is only likely show up if a car is tracked? I don't know, but I've gone through two clutches now since I started tracking the car at club events. Before that, no problems at all (in fact, the first clutch I blew up on the track was actually the original rubber centered unit that was getting on to 20 years old! And I suspect it might still be in service today if it wasn't for tracking the car...)

I'm now ready to try something else beside the OE Sachs unit. If I get an aftermarket clutch disk, and it fails as well, I'd probably look seriously at upgrading the car to a 951 spec clutch. If _that_ fails, then I might have to consider possibilities like torque tube bearing problems.

But one step at a time. :-)

 

Mark,
Thanks for the detailed response.

In the first attachment is a picture of a disc with your failure. It has some causes as well.
You did not mention any additional damage to the FW or TO bearing, good to hear.

Here is the entire link--it is a PDF:
http://www.schaeffler.com/remotemedi..._086_us_us.pdf

GL
John

 

Thanks John. I'll have a good look for clues while the car is in bits to see if I can identify any possible problems as indicated in the LuK document (e.g. pilot bearing). Cheers.