944 Clutch Issue - Need Advice

[brettdawnj]

I have an 86' 944 that I just rebuilt the engine on. I didn't touch the clutch, other than study the wear on the plate, because the previous owner had just had a Porsche dealer replace the whole clutch assy within the last 10,000 or so miles.

Upon my engine install, everything was perfect. But within the first 3,000 miles, while driving and pressing the clutch, it slammed to the floor and got stuck... much like I have learned from many of the wonderful threads on this site. But, I believe my issue is much more than a master and slave rebuild and bleed job.

When I take off my slave cylinder, I can grab the release lever and activate it back and forth with out any issue... in fact it seems to have too much stroke.

I can't get my head into this location to really see clearly what is happening, so I have taken a couple of photos to assist me with the view. Here they are:


This first one is a little further back for a better overview:


This next one is closer in to see the throwout bearing and clutch plate in more detail:


From what I am seeing through the inspection hole is that it seems that the throwout bearing has come loose from the pressure plate. In fact, when I imagine the motion of the slave rod pushing on the release fork, it appears that this system is designed to have the throwout bearing "PULL" on the pressure plate to release the clutch.

My experience from other cars is that the throwout bearing is always pushing on the pressure plate to release it. But this car seems to have a method of "attaching" the t/o bearing to the pressure plate and it "PULLS" it out to release the clutch... IS THIS CORRECT???

The following illustration is what I "IMAGINE" is happening. Could someone confirm if this is right or wrong? If this is my problem, then it looks like this car will be dead until someone can do the 20 - 30 hour grueling task of a clutch removal.

Here is the crude sketch of what I think is happening:



Any advise would be greatly appreciated as I want to make sure I really need to do a complete tear down before I attempt it.

Thanks - Brett

[John_AZ]

Brett,

Nice graphic.

My guess is the retaining clip on the TO (throw out) bearing was not installed correctly or broke. Here is a picture from Art Z and the link to explain better:



How to remove throw-out bearing retaining ring?

Complete removal of clutch is required anyway.

Your picture shows a lot of rust on the PP (pressure plate).

Was the clutch underwater?

John

[brettdawnj]

John, to answer your question, the car stood with the engine out while I was doing the rebuild. So I suspect some rainwater got down there and created this surface rust.

You stated that I will need to take the clutch out for a rebuild, but I still am not sure if what I am seeing or imagining through the hole is correct. Does the T/O bearing somehow pull on the pressure plate tabs to release the clutch? This seems backwards of other cars I have worked on.

Also, the clutch removal process that I read on this site, does not seem like a couple of hour job. Although is doesn't appear to be too difficult if everything comes loose, it seems to take people 20 - 30 hours to do so.

I have also read that there are 3 approaches for this replacement:

1. Most common way seems to be to remove the rear axles, tranny and then the torque tube to get access to the clutch.
2. Another seems to go in from the front side and remove the engine... and for this, it seems there is 2 common approaches. A) Bottom side removal per most manuals, and B) top side removal (what people tell me who run them at the track). Note I did a top side removal for the engine build and found this challenging with removal of the speed reference sensors and also the engine to bell housing alignment.
3. The least read about method was to drop the axles/tranny/torque tube as an assembly. This seems to look the easiest if one has the vehicle at the right height for removal and you can handle the complete parts as an assembly on the way down

Does anyone have any recommendations on which method to use if I have limited time to do the work?

Thanks, Brett

[Rasta Monsta]

I just did my 931 by dropping it down. Saw no real advantage of this approach, and installed it from the top. 6, 1/2 doz.

[brettdawnj]

Still looking to see if someone can clearly confirm if my illustration is correct on how the clutch releasing actually works. Does the T/O Bearing actually "PULL" on the flex plate instead of "PUSHING" on the flex plate?

Also if anyone has any comments about what method of access to the clutch is best, I would appreciate hearing about the pro's and con's of each method.

Thanks Brett

[Rasta Monsta]

Yes, the TOB pulls on the PP fingers to release it. Your diagram is correct.

[John_AZ]

I have a picture that will explain Rasta's correct answer.

In your graph, the clutch fork will fit between the flat wide surface on the right of the picture and the right ridge of the TO will be where the fork "feet" grab.

In your pictures, I think the snap ring broke or was not seated correctly. There is too much of a gap between the PP diaphram spring fingers and the snap ring.

More info at:
http://media.centerforce.com/DiagGuide/DiagnosticGuide04DL.pdf




Methods.
Back breaking and miserable.
Allow 2 full weekends==Friday night to Sunday night. 3 weekends if you have trouble with bolts or the sensor bracket.

You will need to buy parts in between.

I use the "drop transaxle" rear method.

Get your parts from our forum sponsor-Pelican.

A tube of CV grease.
New transaxle fluid and cleaner to polish the transaxle.
New clutch fork bearings
New fork rod if the fork bearings pressed deep into the fork rod
New clutch fork if any cracks or the feet are excessively grooved---minor groove, smooth flat
New pilot bearing
New disc guide tube
New RMS----yes replace the rear main seal
New FW bolts and you should get new PP bolts
New ehxaust manifold flange gasket
New TO bearing if yours is old
Check the thickness of the clutch disc------if minimum replace. If rubber replace.
Resurface the FW
If the PP finger tips are worn down--replace
WYAIT--replace the heater control valve if it shows signs of leaking at the pivot.
Regap the sensors
Change the fuel filter
Change the fuel tank to pump hose
Replace the fuel tank fuel strainer
Tools.
Buy a set of SnapOn metric triple square (cheesehead--12 point or XZN) hex or similiar quality.
Buy a set of SnapOn metric hex or similiar quality

A sturdy floor jack to remove the transaxle.

Thats about half of it

A couple of procedures:
The black background makes it more dramatic...
944 clutch repair

Rasta's favorite:
Clutch Replacement

GL
John

[brettdawnj]

Thanks guys, I clearly know this is a full clutch removal process... I was really hoping that my understanding was wrong and I wouldn't need to remove the whole thing. You guys are great. Thanks for being so supportive. Brett