Problem with Testarossa clutch

I'd have to say that it shouldn't be that unexpected to have a problem in a hydraulic system after ~20+ years if it has never been disassembled and truly cleaned and rebuilt (especially one that isn't used regularly -- even if it's been serviced per schedule). Your symptom is most indicative of some debris and/or corrosion products sometimes getting caught between the close-fitting piston and bore (either at the master end or the slave end), or in the close-fitting areas of the throw-out bearing mechanical motion pieces, and then sometimes clearing itself or getting sufficiently ground up/crushed to a smaller size to "go away". It's also possible that you have some sort of mechanical problem with the pressure plate mechanical mechanism, but the least invasive thing to try as a fix is to (aggresively) bleed/flush the system and hope that you get the crude out (i.e., bleed, do some pumps, bleed, do some pumps, etc.) -- and that that's the trouble, or, if not, pull the pumpkin off which then gives you access to clean/rebuild the slave cylinder, clean/refresh the throw-out bearing motion pieces, and check the pressure plate condition (regardless of who the bad player is -- i.e., once you're in that far labor-wise, it wouldn't make sense to not do all 3 IMO).

Has your clutch hydraulic system been regularly flushed?

Any long periods of disuse?

Have the pumpkin internals received any attention before?

 

Steve, I have often had this problem on C4 Vettes. My experience is that it NEVER cures itself with use - it just slowly gets worse.

The ZR-1 gurus all say to replace EVERYTHING if you replace ANYTHING - i.e., if you need a new slave, replace the master too and the line. Their notion is that you can never get all the crud out without a full replacement.

How do you see that? Urban legend to make us spend more money, or the real deal?

 

I think it's hard to say that there's a one-size-fits-all decision for every car as it's a (design x cost) issue, and you really need to stop/fix the source of the debris. For example (and this is just speculating), let's say that there is some specialty coating used in the master and slave pistons or bores that is particularly susceptable to damage from water, but works well as long as the fluid is changed regularly. But once damage to the coating has occurred, then, even if the system is well-cleaned and the fluid is well-maintained, the (exposed) base material sheds or generates more new debris. In such a situation, I could see how, once you have a problem, you could never resolve the problem unless everything is replaced. Same things for the lines -- if they are a continuing source of debris, you could flush things out, rebuild the slave, and it could work well for a while, and then the slave fail again. Sorry I can't be more specific, but you can only really rely on the collective group experience (and for us, that's even more difficult because of the lack of use).

I agree with you that the OP will be very, very lucky if just a vigorous bleeding/flushing solves his problem for any length of time. We argue about the time interval for timing belt changes, if the OP's system has never been opened, one could argue that 20+ years of service isn't too bad

 

OK, just as a side-issue rant...why, oh why - did we almost universally go to the hydraulic operation system rather than simple mechanical linkage?

OK - I know why. Engine location got in the way of simple linkages. But not, I submit for Corvettes and other front-engine cars.

But, all of this kind of makes you look back in fondness for the lever to the bellhousing, (or at least lever to cable to bellhousing) in previous cars.

 

Lower pedal pressures with heavy duty pressure plates required on high HP cars. I used to work out with 750lbs on a leg press and some of the clutches in old big block cars of the 60's and 70's were difficult to press. Hydraulic clutches have made driving a 500HP car something anyone can do.

 

Thanks, Rifledriver - but educate me a little more.

First, these hydraulic systems are not assisted, are they? Doesn't all the energy come from the foot pressure still? Or are they just using a sort of hydraulic "leverage" to get big pressure with little travel to work the heavy clutch springs?

Second, I seem to recall that the same general effect is possible mechanically - specifically, later P 911 cars had something called an "overcenter spring" to lighten the effort but were still mechanical, or do I hallucinate? For sure, my 993 is as light or lighter than my old low-HP 911T,E,orS cars.

Third, from the real land of the Yik-Yak - I seem to recall a Bugatti (or maybe some other classic - Stutz or Duesenberg) patent that made a lightly sprung clutch grip harder at higher RPM due to centrifugal forces - does that still get used in modern cars.

Thank you - I too am far to fragile (or far too lazy) for a 750lbs leg press now.

 

They are not assisted but by juggling the cylinder sizes ease of compression can be achieved within the limits of the physics involved.

Old 3 finger coil spring clutches often had centrifugal weights even in the US, it was quite common. Problem with those is at high rpm it becomes even harder to compress the clutch, not good for quick shifting. Diaphram clutches used in most modern cars, including Ferrari since TR/348 have the benefit of geometry that requires less pedal effort to hold it down than to push it down. At least until the clutch wears to the point that the geometry changes due to different angles of the fingers. The reason Ferrari went to a double disc on BB/TR was to reduce clutch pedal pressure. The springs are lighter because the surface area is much greater and you can get away with it. The side effect is a clutch "Feel" that many cannot get used to with the result being less clutch life on a very expensive clutch. TR512 went to a single disc which was a big improvement and further fiddling with design of the release system kept the pedal pressure down and the feel was easier for most to cope with. The same clutch found its way into 456, 550 and 575. May still be in use for all I know.

 

Mine does the same thing from time to time

 

Thank you, sir.

 

So the next question is, can the 512TR clutch be retrofitted in place of the dual-disc TR clutch? I imagine the hydraulics would have to be changed as well.

 

Lots of spensive parts.

I talked to the owner of the local TR that has 225,000 miles on it the other night about possibly bringing it in for a clutch. I asked him which clutch we would be changing. He told me it was the second. He had the discs relined once and now the original pressure plate has just given up.

Do you think you really need to upgrade?

 

Dear Ferraristi,

To add to Rifledrivers postings...


On the slave cylinder actuator, there are 3 seals. One an outer, an inner and a dust seal. The dust seals go bad and get hard over time.(The others go bad and leak). It can make the clutch pedal stick and increase the effort to push.

I'm in the process of replacing these seals and Ferrari told me that they don't even sell the dust seal anymore because they caused more problems than they fixed. Ferrari told me to just leave it off....seal # 28 on TAV 28 Chassis # 80095-80146 US. When I removed mine, it was hard, brittle and broke up in little pieces as I removed it. Oh yeah, it made my pedal stick to the floor....not fun.

I go with Rifledriver....check the hydraulics.


Shamile

Freeze....Miami Vice !

 

No, I'm easy on my clutches but always interested in taking advantage of design improvements if they are cost effective.
My TR got a fresh clutch about 6k miles ago so it won't be an issue for a while yet, (I hope).

 

I have thought about doing it to ours just for the sake of a better, nicer clutch feel but there is no bolt together conversion and you really do need to buy a bunch of spendy stuff to get to the point where you can fab the rest.

 

So all Testarossas up to the 512TR have dual plate clutches?

My 86 feels just fine to me, but then I hardly ever slip it. I just let it all the way out at idle and then go.

With this much torque, slipping it is hardly ever necessary.

 

The clutch as it is feels fine to me, especially in comparison to the heavy clutch in my old 308. (Great exercise).
I'll just leave it be.