Steve Weiner-Rennsport Systems

Seized needle bearings is the normal cause. As these get contaminated with clutch dust, they require increasing force to move the release fork and finally the aluminum boss fails as the hydraulics are strong enough to do this.

One either welds the broken piece back on and remachine the bores, or install something like the CMS component.

I've never installed the Cup HTOB in a 964/993 so I cannot say how well these work. The only HTOB's I've used are Tilton ones made specifically to work with 5.5" race clutches and these have a VERY short throw.

Indycam

I see that two mounting screw holes are already there .
http://www.tiltonracing.com/content.php?page=hydraulic

JasonAndreas

The most inexpensive fix will be to create new mounting bosses. The most difficult part will be finding someone that can build up the welds properly. Try the welding instructor at a local community or technical college. You'll want to use a graphite EDM rod ($20) as a positive (male) mold and then build the welds up around it. Porsche sold a special cutting/reaming tool to create the proper diameter openings. I may have posted the part number and pictures a few years back. Make sure you drain the case and you'll need to do things in small incremental steps with external cooling but the whole thing can be fixed for less than $500. (BTDT)

Laker

Cheers Steve

John Rygg

Had the same thing happen to my Cab about 10 years ago, about 1 month after buying the car.
Had an expensive intro to 964s but it has gotten better ever since.

had to swap the housing out and went through the transmission while it was out. Gave me an excuse to get rid of the dual mass flywheel.

PChar

Thanks Steve, I think I will go the welding route. I have found someone local that can diss/assemble the tranny and ship to Arizona (Patrick Motorsport) which will do the repair for $475.

I dont think so, just the diss/assemble of the tranny goes into the $1800 without the repair itself. I am hopping that the shop who will dismantle the tranny will not find too much wrong with it, because it will significantly increase the overall cost.

Steve Weiner-Rennsport Systems

I think thats a good plan since properly done, its a solid and permanent repair.

PChar

I have had a local shop reweld the clutch fork mounting boss, below in the picture although now I am very confuse with wich clutch fork shaft to use. So many things have been suggested that I ended up buying two different ones.

I have started another tread to have faster response

https://rennlist.com/forums/964-foru...ml#post9403913

PChar

VERDICT:

Clutch Pedeal improperly adjusted.

I ommitted to adjust the clutch pedal travel after replacing the salve and master cylinder as well as new clutch kit. This caused the master cylinder to push to far on the clutch fork, which in turns pivoted too far leaning against the cassing of the bellhousing putting extreme force on the mounting boss. which ultimately failed.

So lesson learned,... always check your clutch pedal adjustment/travel when new clutch component.

Vandit

Interesting.

I just replaced the slave cylinder on my car and did not adjust anything on the pedal.

What's the procedure for properly adjusting the pedal?

JasonAndreas

You don't need to disassemble the transmission to weld repair on new bosses to the bellhousing, draining the oil will be enough. You don't even need to replace the input shaft seal. BTDT.


Do you remember hearing any clicking sounds as the clutch pedal was fully depressed? For anyone else that finds this thread, when the pedal is too far out of adjustment the backside of the release fork will hit the pressure plate and make a loud clicking sound as it grinds away at the sachs logo and part number.

c didy

I'm stuck home with my 3 year old twins today so I thought I'd do a little learning. This is a very nice thread with some juicy bits for sure.

Can someone please tell us how to adjust clutch pedal travel correctly? I know there is a TSB on this but it only lists correct throw, (15.5cm +/- if I remember but don't quote me), not how to measure or achieve it.