Clutch pedal return spring function

[Michiel van Wessem <jmvw@xxxxxxxxx>]

Hello,

I noticed something kind of neat when I installed a new spring to push up
my clutch pedal. At least I thought it was kind of neat. 

This applies to cars that have a push spring to return the pedal.
Apparently there are some that have a pull spring and that's probably
different.

I noticed that the spring only pushes the pedal up when the pedal is near
it's top position. At lower pedal positions, the spring actually pushes the
pedal *down*. I think this is intentional: at lower pedal positions the
hydraulic pressure coming back from the clutch pushes the pedal up. The
lower the pedal, the more push from the clutch and the less upward push
from the spring. Near lower positions, the spring pushes down and cancels
out part of the clutch upward push. Near the top pedal position, there is
no more push from the clutch, but the spring pushes the pedal up (good to
keep your cruise control going). 

I think the clutch return spring and it's position is designed so that the
sum of the two, return spring force and clutch force, will be moreless
constant - the pedal return force is independent of pedal position. 

I have noticed in the past how the clutch pedal doesn't seem to push back
more a lot when you depress it further. 

I don't know if I find this good or not, but I suppose that if clutch pedal
feel is modulated, that's a luxury car thing. I liked discovering that
something like this is carefully designed (or developed, considering that
some (earlier?) cars had the pull spring). Pretty neat.

Michiel ('87 325es <http://www.monmouth.com/~jmvw/cars/BMW/>)
PS: sorry if anybody minds me sending this to both lists. I can't make up
my mind; I like both. 
- ----------------
>From Jackson, NJ

  e-mail at night: jmvw@domain.elided
 e-mail while day: jmvw@domain.elided

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