I am sure not everyone is real familiar with the pull type clutch system used on the 930 but some will likely have some input.
Some times things are hard to explain, however the T/O bearing is pulled back by a internal fork in the bell-housing. The fork makes contact on to flat areas of the T/O bearing which in turn gives it a good place to draw back the T/O.
My clutch made a snapping noise and the pedal went limp. I can see the T/O bearing inside an inspection hole, the flange where the fork pulls on the bearing has broken off. Luckily at this point nothing else has been damaged.
Does this happen much and is there some other things to look at which might have caused this.
I am trying to get a head start before dropping the transmission.

I would think this could be caused by overextending the clutch. When you step on the pedal (when it worked) did the pedal effort go from hard to easy, then hard again? If so, you're hitting the end of your clutch spring travel. The effort should get less the farther you press down the pedal.

so one of the little fork "ears" that grabs the t.o. broke off? Or the t.o. bearing itself broke off? Either way, that sucks. I haven't heard of that one yet, but have limited experience as well.

If the actual fork broke, I would say talk to Bill at Bill Brewster Auto (I think that is what he calls his place) in San Clemente down by you - right off the 5 (look him up, I don't have his # with me). Anyway, I bought my 930 from him and he seemed to be a straight-up, super-knowledgeable guy that has been a Porsche mechanic for years, so he has certainly seen more than a few 930s in his time. Maybe he has seen this, and if he hasn't, then hopefully that is a sign yours was a fluke... and he can probably locate another fork for you easily.

If the t.o. bearing broke, then talk to Kennedy. I hate how stiff these Kennedy clutches are...

Well I was able to fish out the parts from the inspection hole and it seem both T/O bearing ears broke off. I depressed the clutch at a stop and felt/herd a snap, I then rolled into parking lot and depressed it again and herd another snap. Both ears were still hanging on and didn't get involved with anything. I have an idea the T/O support tube may have developed a ridge and it just stopped the bearing movement. I also think bondo and byndbad914 have good ideas, for one I have never set a limit to the clutch movement. I really don't think that was a problem however because the limit of the slave is set real close. I am using a much longer outer clutch arm and have very little movement to spare. That has been something I have thought about prior to this setback. I must admit I have sprayed WD-40 on the T/O bearing and the support tube and the clutch effort got far less. No big deal here just another little thing to do some R&D with. Well see by tomorrow whats going on inside. What else can you do? Fix it and move forward. I would like to surely replace the guide tube and T/O bearing along with making sure the alignment is good.

The guide tube should be greased. If WD40 helped, that means it was under-lubed. Sounds like that may be your problem.

Hey that may be just what was going on, I did put some grease on the tube a number of times but its not easy to get good coverage while the transmissions in the car. I also realize WD-40 is a solvent and it may have cut the tube up over time and created a ledge that just got big enough to bind up the bearing as well. I knew I was playing with fire using the WD-40. Your thought about bottoming out the T/O bearing is still a real possibly. I seem to remember feeling the clutch pedal moving down just a slight bit more in the last two days. The T/O flanges are cast so I don't think they would bend much and if they did surely only once or twice before all hell broke loose. I may get the trans out tonight or surely tomorrow morning.

Hehe, I can't even imagine trying to lubricate that while it's installed in the car. I don't think I'd spray WD-40 in there either, for fear of it contaminating the clutch friction surface. They do make spray grease, but I guess that's a little too late to help.

in fact, any grease you had in there you would have washed out with the WD40. That stuff is really bad news - clearly you knew you were not using the right thing from your post, sounds like may have been a tough "I told myself I shouldn't do that" thing. I do that all the time - "dammit, I knew better..."

You will have to get another guide tube for sure.

A little white grease goes a long way - the tolerances are tight enough (should be at least!) that you won't get a thick amount on there. The small amount is good 'nuf.

And definitely check the overall disengagement travel - bondo is right on about that. I set my clutch just enough to fully disengage. I attempt to roll the car back with my left foot (sitting on the long - car shut off of course) and engage with my right foot. I set the pedal travel just a little passed the point the clutch is disengaged enough to allow me to roll it back freely. That is the simple "one man" way to do it at least, and I have yet to ever over-extend a clutch.

Sorry to hear you have to remove the trans and put a few new parts in (guide tube & T.O. bearing). These parts will cost approximately $250-300. Actually, I'm quite glad to hear that you didn't explode your box or some other real expensive ordeal...still a pain in the ass I know. I had plently of trouble getting my Kennedy clutch package, T.O bearing, guide tube, and custom hydraulic clutch to work properly on my V-8 car. I had the god damn trans on and off the car about 8 times (in less than a month!) I learned two things: One, I did not have the proper grease on the guide tube. It wore away real fast and my clutch effort became insanely difficult...not that it wasn't like a leg press to begin with. Two, I learned how to remove my trans and have it laying on the floor in about 30 minutes. I talked to Bobby Hart @ CA Motorsports and he recommended me to use Mobil 1 synthetic grease on the guide tube. After installing a new T.O bearing & guide tube (with proper grease) it worked flawlessly. I'm betting you are right...when you take the trans off you will immediately discover your guide tube looks like it was in the middle of Word War III.

Good luck,

Bill

Surely if it were any other car I would unload the thing, but after getting it to run right its just way to fun to drive. Most times when it brakes I can look back to a decision I made where I knew better. I did see some wear marks on the T/O tube but instead of replacing it I just buffed it out. Bad idea, I also didn't know what grease to use so I just used bearing grease, another bad idea. I love the way the car accelerates its just pure fun so a break down now and then is just the price you pay to go fast, or in my case rushing things along.

I removed the transmission and here are the parts The T/O tube had a ridge and it looked like it may have bottomed out against the tube flange as well. I am replacing the T/O, the tube and the internal clutch fork. I think with the new parts and correct adjustment things will be fine.

I'm actually surprised to see the guide tube looking as good as it does. I do see some wear though. How long does it take to drop your trans now? I assume you have had it on/off a few times...like I have.

Yes I have had it out countless times, I have air and it takes about 30 minutes. I don't rush it. Installing it is a different story, as you know seating the input shaft / clutch is a bit more detailed.
The tube has more wear on the bottom side, thats not the norm considering gravity but I have a spring pulling up on the outer clutch arm to help carry the extra weight of the outer assembly. Its hard to see but there is a grove acting like a small curb and the wear marks travel to the end of the flange. I am not sure what happened but it looks like the T/O bottomed out with hydraulic volume to spare. I must have pushed the clutch 1/4 inch or so further and snapped the flanges. When I first noticed something I depressed the clutch and herd a snap, kept the pedal down and left off in first gear, depressed the clutch again and herd another snap. Then there was no clutch pedal effort anymore/ pedal just sat on the floor / not good news in traffic. I got lucky and rolled into a parking lot.


The fact WD-40 helped with pedal effort says there was a lot of friction in the mechanism. I am going to make sure everything is new and lined up along with having the correct grease. Waiting for parts now. It's likely going to cost around 500 bucks to get it going again. Sh*t happens!


Since I have it out you know I am trying to cook up a different clutch pedal master system(still trying to come up with something new). I keep looking at how we use electric motors, IE windows. The idea of using an electric / linear actuator seems possible. You couldn't or its not likely that a foot control would work, it seems a finger control would be essayer to modulate. Well shoot I keep trying to get the idea going................................................................................................................................................... Ha Ha Ha