Stiff clutch pedal = failing clutch?

Bernie Benz b.benz at
Sun May 4 09:12:37 EDT 2003


Your point is well made, that it is clutch disk wear that alters the
diaphragm spring's "clamped" static position and thus the operating force
required to release this nonlinear spring.


> From: DasWolfen at
> Kneale and Wolff,
> The reason a clutch feels the way it does involves how close to "center" the
> diaphragm arms are on the pressure plate and thats a function of clutch
> thickness.
> The center or breakover point of the pressure plate diaphragm is the point
> of max resistance. Its very like a compound bow, when you begin pulling the
> bowstring the effort required increases until you get to the breakover point,
> once past that point effort drastically decreases. A new clutch disc is thick
> enough to keep the pressure plate very close to its breakover point. As the
> clutch wears it gets thinner and requires you to move the pedal further to
> reach the breakover point. Eventually the clutch gets so thin that you never
> reach the breakover point of the pressure plate. You feel this effect in the
> pedal as stiff at the top and easy at the bottom when new and easy at the top
> and stiff at the bottom when old.
> Sorry for the poor explanation but its the best I can do without drawings.
> Keith

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