Why won't my clutch work?

That is what happened to my clutch/pressure plate also.
Replaced clutch kit and car has been going strong ever since.

 

Here John, I found a pic of my failure

Looks like mine had some more metal fatigue than yours
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A long line of folks have suffered the same fate. You're in the company of some fine Fchatters (Pap348 notwithstanding )

Time for a new PP and disc.

 

Does AP know how to build a clutch that will last in a passenger car? Maybe they should stick to racing clutches that get replaced regularly. Breakage of that kind is nonsense.

 

What causes that?

 

Mine quit working when it only had one finger to salute with.


When I opened it up, the hydraulic clutch release "piston" had traveled so far that the guide rollpin had sheared off.
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Looks like a beer bottle opener now

 

So has there been any improvement in current production pressure plates from AP?

Has this ever been an issue with the 355 pressure plates from Valeo?

 

I read somewhere (in the Aussie section I believe) that the problem is supposedly caused by the throwout bearing having too much travel and it overextends the fingers as the friction disk wears. ferrarifixer posted this info IIRC. I can't attest to the accuracy of this "cause" however it is food for thought.

Dave

 

Mine has done that twice i the last 17 years!! Well, now I know that it just wasn't me!

 

Is it only the twin-disc clutches that are breaking pressure plate fingers, or are there also single-disc clutches doing the same thing?

Is it only AP clutches breaking, or are Valeo clutches also breaking?

I've been looking at the manual. It says that the maximum stroke on the hydraulic clutch bearing is approximately 20mm (around 3/4"). I wonder what the rating is for the maximum stroke on the pressure plate fingers? If it's less than 20mm, then bingo, we gots a problem! I couldn't find this figure on the AP website or in my Essex catalog. But it certainly seems that the fingers are being overextended.

Possibly also related to this, the manual says that the maximum travel on the clutch pedal (limited by adjustment screws) is supposed to be 126mm (just about exactly 5"). QUOTE: "Do not use the entire cylinder stroke (on the clutch pedal) because this would be excessive and give the sensation of forcing the pressure plate spring."

Hmmmm. They are saying here that too much travel on the pedal (and thusly on the slave cylinder) is plenty bad medicine, Kimosabe. I tried to measure the travel on my pedal, and it isn't easy, but it looked like 5" all right. It's important to note that the pedal does NOT go all the way to the floor if it's adjusted for 5" of travel. If your clutch pedal goes all the way to the floor, you better find out why, because it apparently isn't supposed to.

When I recently replaced my worn out AP single disc clutch, I was rather unhappy with what I found. For one thing, the diameter on the AP disc is smaller than the specification in the manual, giving 10% less surface area than a Valeo disc of the proper diameter. And the hub on the AP disc is not a separate part, it's part of the metal plate, and doesn't look near as stout as the Valeo hub, which is very solidly rivited in place.

Personally, I would keep clear of AP components if possible.

 

Maximum release travel for the pressure plate fingers is definitely less than 20mm. Pretty sure it's 12.5mm, which is more than many other clutches with only 9mm allowed.
On the topic of clutches, if my numbers are correct, disc thickness should be 8.38mm new, and minimum worn thickness of 6.88mm.

As for AP components, they're at the top of the game in clutch and brake components for racing. Nothing better. But somehow these OEM street parts have problems.

 

Thats right. Ferrarifixer and one of his mechanics I think, said that the 348 clutch setup was 'overthrowing' the pressure plate fingers, causing them to stress/break over time. They were looking into it, but now Ferrarifixer is banned.........so will never know.

 

Did anyone experience a soft pedal or problems with pedal adjustment before total failure?

 

My pedal felt the same, but I was having trouble selecting gears. Upon disassembly, I found 6 fingers were broken off.

 

Wow, I got to say, I have never seen this in all the clutch service I have ever done on Corvettes, Triumphs, Datsuns/Nissans, Volkswagens and BMWs. I am now going to minimuize the number of shifts I do per drive.

 

Funny because I've also seen it on Nissans and BMW's. Sad on Ferrari's though, because they generally have very few miles.

 

He had an 'altercation' with the Aussie Mod.