Mike Murphy

Good question. It can easily be argued that the rubber center will absorb drivetrain vibration and engine noises, but how come some spring clutches make noise and other don't?

Peter Zimmermann

ice: You've got a spring-centered disc, it's the only one available. Remember, the 915 cars are a completely different animal. Porsche tried the rubber-centered disc in early SCs, the result was a total disaster. Failure before 20K miles was not unusual, by '82 all new SCs were delivered with a spring-centered disc.

dshepp: Now that would be a monumental task, involving complete disassembly of no fewer than twenty cars and making many measurements, after each was evaluated using db meters, etc. Even then an answer might not be apparent. Sometimes issues like this must just be accepted.

murphy: You are the owner between a rock and a hard spot! You have to figure out how many miles are on your just-failed disc, if possible, then try to figure out how many track hours are also on it. Your car's PO might not have been a technically correct driver, so loads might have been placed on your clutch that will even skew the total mileage. If you're planning on doing a DE every weekend during the summer you might have to compromise and use the spring-centered disc. I think that it will be decision time for you after the engine is out and you see exactly what failed on your car.

David: The amount of noise that your little gem will make with the pretty stuff removed from the floor of your car is amazing. My first time in a real race car was a true wake up call - cars are really noisy, and I thought that everything was either breaking, broken, or falling off. Once I was conditioned to the environment inside that car the noises no longer mattered. In your case what you want to concentrate on is change. Establish a baseline noise level, you'll know when something is changing. Cheers!

theiceman

Hey Pete thanks for the update ... it was only from a year ago....

PS I'm reading through the 8th edition .. ( I kinda fancy a 993 now ) ..

Mike Murphy

I will update this post after I see the damage. Hopefully, I can take pictures as well.

theiceman

make sure you take pics ... I have never actually seen an exploded clutch ...

good luck

Joe Rose

Say folks, let me throw in my two cents worth here. It's been a year since I started this thread--a year since my unpleasant experience with a spring-center disk. All I can say is that I love the quiet of the rubber-center one that replaced it. The original disk in my '89 Carrera was one with a rubber center. It lasted 80K miles and was somewhat worn--not exploded--when I had it replaced. If the rubber center disk I now have lasts that long, I'll certainly be happy. Let me remind you, though, my car is strictly a street car. It sees no track time at all. Those of you who regularly do DE, etc. may really be better off with the spring center disk, despite the risk of having more gear rattle for street driving. I guess this boils down to a matter of individual choice based on usage.

theiceman

Joe where did you get your clutch? Is it still available from Porsche? ( the rubber centred one ? )

Joe Rose

I didn't do the job myself. I had it done at Eurowerks here in Charlotte. No matter, though, the rubber center clutch is still available from Porsche. The part number for my '89 is 95011601204. I just checked the Porsche price (from Stoddard in Ohio) and it lists for $600. It is also available from Pelican for $542. I didn't check the price of the spring center one, but it is quite a bit less expensive if I remember correctly.

Mike Murphy

Joe, there is a similar thread on pelican: http://forums.pelicanparts.com/showt...=&pagenumber=2.

Most people have reported that the spring clutch produces no more noise than the rubber one. Based on the fact that you had an increase in noise going from one spring disc to another, I'm starting to wonder if there was something wrong with the original disc, either in installation or in material defect. Granted, the rubber one might be a tad quieter, but there are so many who have the spring version and no noticeable increase in noise.

Joe Rose

The dude on the Pelican board--oregonmon, I think--has an SC with the 915 tranny. Please discount these cars when considering that "there are so many who have the spring version and no noticeable increase in noise". It's only the beefier 950 tranny in the 3.2 cars that seem to experience the increased noise...and not all of them, either. It seems the 950 gearbox was designed by Porsche to last through a series of increased engine displacements--to be able to take the anticipated increases in torque that future engines would produce. As a result, the parts in the 950 are bigger and heavier. If the tolerances in these trannys are on the high side--and most are--gear rattle will be more of an issue with the more rigid spring-centered disc. My mechanic says about three cars out of one hundred will be OK with the spring clutch. The rest will exhibit increased gear rattle. Considering you already say you have some input shaft rattle, I'd say you're a good candidate for the increase. A friend and I did a clutch replacement a few years ago on his '82 911, and we used a spring-centered disc. The results were just fine--no increased noise. Remember, though, this car had the 915 tranny. Even Porsche switched from rubber to spring on these cars after the earliest rash of exploding clutches.

theiceman

interesting..

ron mcatee

I went from the rubber centered to spring clutch in my 88 Carrera several years ago. I haven't had the rattle in this car, but my 87 Carrera had it. Even though the 87 had the rubber centered disk, it still had a rattle. Porsche came out with a "kit" in mid 87 that helped alleviated the problem, but not totally. The 88 and on production cars had all the upgrades incorporated to do away with the rattle.

r911

950?

dshepp806

Spider911:

What were those specific incorporated upgrades you speak of?

Best

KC911

I interpreted the "9" as an upside down "G"