Cowhorn

All of a sudden I am feeling some vibration in the car when I put it into reverse and first gears, but not every time I do so. I feel it also sometimes when I downshift. Is the clutch dying? Is this typically a slow demise or will the clutch just suddenly stop working? 1987 911, 75,000 miles, original clutch. TIA

Peter Zimmermann

Jim: It's probably worn out, and I'll bet the pedal action has gotten pretty heavy also. In L.A. traffic most cars of your vintage need the clutch done at between 45K and 60K miles, so I think that you've done OK.
Pete

ron mcatee

If it still has the rubber center type disk, it is time to change. Once the rubber starts breaking apart, you will have a hard time depressing the clutch due to the crumbling rubber not allowing the disk to engage. One way to check is to shut the car off and go through the gears. If it shifts easily, then that's a first indicator. If you start the car and it feels sluggish and doesn't want to go in gear easily, that is the crumbled rubber particles blocking the disk from going all the way down. If you do have to replace the clutch, make sure the improved fork kit is put in. The new kit eliminates the roller bearing and putting in a new solid pin and improved fork and makes a world of difference.

Diamond Blue

I ended up with a lot of vibration with mine but it let go in what felt like "I pushed it out of gear too soon" bang. This is what my clutch looked like when I opened it up.

ron mcatee

Diamond Blue, that is the rubber centered disk I was talking about. You want to put the spring centered disk in when you go back new.

Peter Zimmermann

Just be aware that a spring-centered disc will be noisy compared to the original.

Here's the deal with the throwout bearing fork... The original design used a fixed shaft secured into the bell housing. The fork was mounted onto the shaft with needle bearings, but dirt was able to penetrate the bearings, dry out the grease, and a very "heavy" clutch action resulted. The update involves using a special reamer to machine the shaft bore to a larger size in order to facilitate the installation of needle bearings with seals. The new shaft floats (rides) on those bearings, and the new release fork mounts on the new shaft with bushings. Visually, if you know what to look for, with the car on a lift you can see the early shaft's mounting tab, which is gray in color, bolted to the bell housing. If the release fork has been updated you will see a silver tab that is holding a plastic plug in place, which will keep dirt out of the left shaft bearing. The tabs, one or the other, will be found on the left (driver's) side of the bell housing near the top.

Good luck with the project!
Pete

LongLiveThe3.2

Pete -

This is great info and just what I was looking for regarding identifying updated G50 forks from the outside of the tranny. Is there any way you could post a picture or diagram identifying the tab you describe above? Does anyone have a picture of this? I know I can't be the only loser here who needs visual aids...

Thanks guys!

Peter Zimmermann

Hey, visual aids are a good thing! Unfortunately I don't have a pic, but if you get a Porsche parts CD it'll have a diagram of what you need. It's the only piece like it on the upper half of the left side of the bell housing. I would guess that it's about 12mm x 30mm - but don't hold me to it!
Pete

Diamond Blue

I was going to replace with a spring centered clutch until I scored a Sach's rubber center clutch kit for $200 on Ebay. Brand new! The first one lasted 18 years and 86,000 miles. Here is a picture of the clutch fork you can see where the needle bearings score the shaft. I am also doing the clutch fork update using the no drill kit. You also need a new 32mm guide tube as well.

Cowhorn

Thanks everybody. I guess it was inevitable. How much should I expect to pay for parts (the spring centered disk and improved fork kit) and labor? I won't be doing this myself.

Also, how much time/ how many miles would you think I have with this clutch before it MUST be replaced if I don't drive it too hard?

Thanks.

Diamond Blue

I would use the Weltmeister kit which uses bronze bearings and does not require drilling the tabs on the transmission. These tabs are weak enough without being made bigger. I would send a picture of the new kit but it is out with the engine where I have been doing the rebuild. The rubber center clutch is also more expensive than the spring centered, go figure.

Crivens

Id say so the T in your cluch is already worn right away.

Peter Zimmermann

Jim: The right way to do the clutch is with a factory clutch "kit," and the factory replacement fork/parts. You will also probably need a new flywheel, remember, you can't machine a hydraulic clutch flywheel. Also, you need a replacement throwout bearing guide tube, which was also updated, and if it hasn't been done yet, replace the hydraulic hose at the slave cylinder.
Pete

Cowhorn

Ugh.

Cowhorn

Crivens...Yes, you are right. It is gone...along with your apostrophe, period, capital "T", and membership dues! Just kidding, Homey. Good catch.