924Board.org

[ZV]

Just look at these pictures of my old clutch.

Good thing the new clutch is spring-centered.

Aaron.
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Shifting is an art, learn it, love it, live it.

1976 Porsche 914 2.0 - Driving Restoration.
1987 Porsche 924S - Daily Driver

[Sickofstreetracing]

I know exactly what you mean. I wish I had a camera when my clutch was replaced. The entire disk was split in two and jagged like crazy on either end! It was a bit of a rough ride
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'87 924S Guards Red, Not stock anymore!

-Weltmeister Throttle Response Cam (gotta start somewhere...)

www.cardomain.com/id/wannabedrifter

[gohim]

Just how long do you expect a clutch to last?

Most people don't expect their tires to last more than two or three years.

Why would you expect a clutch disc made from the same basic material to last longer?

Many people complain about the extra rattling and vibration that they experience after converting from the rubber centered clutch disc to the spring centered clutch disc. Porsche Engineers spec'd the rubber centered disc for a number of reasons. The shorter life (compared to a spring center clutch disc) of the rubber center is the trade-off for decreased driveline vibration and rattling noise. You can't get something for nothing.

[ZV]

[Lizard]

ouch, that is bad, although I had a spring centered one that looked almost new and I managed to break the steel part of it, almost like it pulled itself apart
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3 928s,

[gohim]

You think the rubber centered clutch discs were used because they were leftover from early 944 production? 944 cars were built with the rubber centered disc from the beginning until the end of production.

All the watercooled 4-cylinder Porsches, and many/most of the 911 based cars built since the 924S have been supplied with rubber centered clutch discs.

And I expect tires to last me at least 50K-60K miles before they wear out. I do not buy the super soft traction compounds or dirt cheap tires either. But people keep telling me (and the tire shops and manufacturers state that tires should be replaced every four to five years because of changes/deterioration of the rubber compounds due to heat cycling and environmental conditions.

You may only drive your car 10K-12K miles a year, and get 60K miles from a set of tires. So your the tread on your tires may last 5-6 years. But most people drive their cars farther than you do every year. For the last 10 years, I have averaged 22K miles a year. For the 10 years before that I averaged about 10K miles a year, and for the ten years before that around 25K miles a year. My Porsches get driven less than 5K miles each per year. Most of my mileage is driven in my 96 Ford Taurus. So, according to you the tires on my Porsches should last 12 years or more. That just don't happen, the sidewalls start to crack after 2-3 years, and cracks in the tread area start within 3-4 years. Tire manufacturers do not replace tires that are old for free, just because you did not wear them out before they rotted of old age.

Face it, spring centered clutches are noisier, and transmit more vibration. In some severe use cases, they may/will last longer than a rubber centered clutch disc. Spring centered clutch discs are not better for all drivers under all conditions. Just as rubber centered clutch discs are not indicated for all drivers under all conditions.

Rubber center clutch discs deteriorate and fail because of old age, heat, environmental conditions, abuse, and wear. They may need to be replaced, before the contact surface wears out, because of deterioration of the rubber material, just as tires may need to be replaced before the tread is worn out.

[Phogphire1]

Well I replaced a rubber center disc on my 84 944 with the spring centered disc. The PO bought the rubber hub and kit off e-bay for around $500. It Lasted less than 3 months and less than 2k (but he did have a teenage son) But during the clutch job, you could see all the new parts that he did install. But with 2 buddies and 20+ hours of labor. I don't think that I would ever buy another rubber hub disc again. I never saw the clutch disc before he installed it but maybe it was a manufacturing defect, or maybe it sat on a shelf somewhere.
_________________
Extremism in the defense of liberty is no vice. And moderation in the pursuit of justice is no virtue.

Life, Liberty and the Pursuit of thoose that dare screw with it.

[ZV]

[ProudGecko]

I'm guessing the reason Porsche used a rubber centered clutch is that Porsche has a tendency to stick with their methods no matter how old and out dated they seem to be. 914's originally had rubber centered disks and my guess is Porsche just stuck w/ that design (obviously larger disk to handle extra power tho). Thankfully the clutch in my dad's 914 is the 6 spring 911 clutch
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1988 Porsche 924S
1986 Kawasaki Concurs ZG1000
1984 Mercedes 190D
1973 Honda CB500

[ZV]

[gohim]

ZV, you wrote:

"... Porsche engineers specified the rubber-centered clutch because that's what was left-over from the early 944. There's a reason that the spring-center is a direct, drop-in replacement; it superceeded the rubber-center clutch in the 944..."

Porsche never spec'd a spring centered clutch disc for production model 944 and 924S cars. The Porsche does not sell a spring centered disc for these cars. The spring centered disc is marketed by Sachs (an OEM supplier for Porsche for 924S and 944 clutch discs). Porsche does not sell the spring centered clutch disc as a superceed for the rubber centered disc.

The 924S engines were not leftover early 944 engines. The 87 924S received the same engines used in 86 944 production. These engines have later part numbers, not the parts used in 82-84 2.5 engines, and the internal parts are not compatible with the earlier engines. The 88 924S received the same 160hp 10.2cr engine that the 944 received. How can you state that the 924S has a early 944 engine? It may have the same or similar power output, and most physical dimensions are the same, but they are not the same engine.

[gohim]

Cast iron will last longer than rubber when exposed to air polution, and UV energy.

Does that mean that tires should all be made of cast iron?

Of course not. Performance Characteristics also help determine what the best material to make a component from would be.

Longevity is one characterisic that should be consider by sometime considering a new clutch. To some people, a quiet, vibration free clutch is more important than simply going out and buying component with the highest usable mileage claim.

[Joes924Racer]

Never had one both of the ones I ve had to work with[the old one that I removed ]and the new one I put in were spring discs.
Joe D.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[ZV]

[ZV]