Clutches on high performance cars?

GRtak

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I got into a conversation today about clutches. One of the guys in the group has a Saleen Mustang and said he has to have the clutch done about every 20k miles!?!?!? So he basicly has it done in the spring every other year(parked winters). Another guy has the same year Mustang GT and gets more than 40k miles. Is this normal or did Saleen not upgrade the clutch? And if a warmed over Mustang eats them this often, how often does a Porsche, Lamborghini, Ferrari,etc.?????

BTW: He thought it was a problem too, but everything checks out in the clutch assembly.
 

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This is somewhat normal with the Mustang, as I understand it. It has to do with the cable-operated clutch they use. It actually doesn't disengage the clutch all the way with the pedal in. Heavier performance clutches can make the problem worse.
 
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argatoga

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This is somewhat normal with the Mustang, as I understand it. It has to do with the cable-operated clutch they use. It actually doesn't disengage the clutch all the way with the pedal in. Heavier performance clutches can make the problem worse.
Wouldn't performance clutches weigh less?
 

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Wouldn't performance clutches weigh less?
The flywheels might, but that's not what causes the wear. It's the increased spring pressure of the pressure plates on performance clutches that makes it worse.

Remember, the more torque capability, the heavier the clutch effort (assuming the same actuating system.)
 

InfernalVortex

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This is somewhat normal with the Mustang, as I understand it. It has to do with the cable-operated clutch they use. It actually doesn't disengage the clutch all the way with the pedal in. Heavier performance clutches can make the problem worse.
Wouldn't this wear on the synchros pretty badly then?
 

thedguy

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There are cars like the e39 M5 which arent' much better engineered. They decided that the clutch from a 525 would be just fine under the double torque and HP increase of the M5 v8.... they last 60k even when mildly driven.

Wouldn't this wear on the synchros pretty badly then?
Yep.
 

Spectre

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Wouldn't this wear on the synchros pretty badly then?
Yes, but not anywhere as badly as you might think; an off the cuff guesstimate is that it reduces their life by about 10-20%. Typically, it lunches the input shaft bearing and the pilot bushing/bearing first as they're the ones that end up taking the increased load.

This is why Mustangs can seem to eat clutches and nobody thinks twice about it. GM has their cheap-specced transmission component problems; Ford has problems with clutch life on RWD cable-clutch cars.
 
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CraigB

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I can tell you my cheapy replacement clutch has lasted about 3k so far in my Mustang with tons of hard launches. I don't expect it to last much longer though, I think it's already starting to slip...
 

Spectre

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I know it's more or less irrelevant on most mid engine Ferraris, as traditionally the engine is removed at 30,000 mile intervals for maintenance at which time the clutch is changed whether it really needs it or not.

Most 911 types seem to have pretty long clutch lives for performance cars - most seem to get well over 60-90K out of a clutch.
 
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awdrifter

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What about double or triple plate clutches? Will they last longer in high hp cars?
 

Spectre

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Supposedly, yes - but the Mustang's wretched cable operation system means that the primary plate will get chewed up just like the stock ones.

If you want to watch this in action, jack up and properly support a manual Mustang sometime, take the driveshaft off, start the car, put it in reverse and have someone hold the clutch pedal all the way to the floor. Then go under the car and depending on which transmission and how much friction it has internally, watch the output shaft slowly revolve.
 

NooDle

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I hear Ferrari's, especially older ones, need a new clutch every 5-10.000 kms...
Expensive job too, at 2500? a pop
 

prizrak

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Supposedly, yes - but the Mustang's wretched cable operation system means that the primary plate will get chewed up just like the stock ones.

If you want to watch this in action, jack up and properly support a manual Mustang sometime, take the driveshaft off, start the car, put it in reverse and have someone hold the clutch pedal all the way to the floor. Then go under the car and depending on which transmission and how much friction it has internally, watch the output shaft slowly revolve.
So what you are saying is that hydraulic clutch would do a better job in this case? Or is it the problem with the actual system that Ford uses rather than a flaw of cable clutches?
 

thedguy

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So what you are saying is that hydraulic clutch would do a better job in this case? Or is it the problem with the actual system that Ford uses rather than a flaw of cable clutches?
It's just Fords failure to engineer it right.
 

Spectre

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So what you are saying is that hydraulic clutch would do a better job in this case? Or is it the problem with the actual system that Ford uses rather than a flaw of cable clutches?
I am not a fan of cable clutches in the first place, but they are easier to assemble (no bleeding required after installation on the line). A hydraulic clutch would have been better from a "range of travel" and self-adjusting point of view. However, a cable clutch system doesn't have to have the problem that Ford's does.

The problem with Ford's cable clutch design is that it's this Rube Goldberg contraption that doesn't have enough travel or adjustment available to it. You can't really adjust it so that it completely disengages the clutch when the pedal is depressed without having a problem with insufficient pressure on the clutch when the pedal is released (leading to slippage in gear while under power, which is even worse.)

They could have designed it to have the travel it needed, but then the bellcranks and stuff wouldn't fit - or the pedal effort would have been undesirably heavy, etc., etc.
 

CraigB

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The only ones with a bell crank are the 4-cylinders. The 5.0 has a single cable from the quadrant to the clutch fork. I eliminated the bellcrank on mine by finding an earlier turbo 2.3 bell housing and switching to a 5.0 style cable.

The stock setup is self adjusting, just pull up on the clutch pedal to re-adjust. However these quadrants where made of plastic and known to fail. I just helped a buddy of mine switch his '89 over to an aluminum quadrant and an adjustable cable. He says the clutch feels much better.
 

GRtak

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Supposedly, yes - but the Mustang's wretched cable operation system means that the primary plate will get chewed up just like the stock ones.

If you want to watch this in action, jack up and properly support a manual Mustang sometime, take the driveshaft off, start the car, put it in reverse and have someone hold the clutch pedal all the way to the floor. Then go under the car and depending on which transmission and how much friction it has internally, watch the output shaft slowly revolve.

Why not just lift the rear end and watch a tire spin? I have seen this on other manual transmission cars.
 
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