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Old 05-23-2002, 11:37 AM   #17
romanom
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Member#: 16215
Join Date: Mar 2002
Location: In a place with no laws, just "guidlines"
Vehicle:
2002 WR WRX wagon

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Quote:
Originally posted by Jon Bogert
Mike just to clarify, I think you got something reversed:

A larger MC results in...
> less pedal travel
> a firmer pedal
> less hydraulic advantage

A smaller MC results in...
> more pedal travel
> a softer pedal
> more hydraulic advantage

Larger caliper piston area results in...
> more pedal travel
> a softer pedal
> more hydraulic advantage

Smaller caliper piston area results in...
> less pedal travel
> a firmer pedal
> less hydraulic advantage
Say you have 2 tubes, one is 1 sq in the other 2 sq in. Tubes are filled with fluid with a piston inside. You apply 100 lbs to the piston.

The 1 sq in tubes will produce 100PSI at the other end while the 2 sq in tube will produce 50PSI at the other end. Which is all that's coming back at you. So your displacing the same volume but building less pressure with the larger MC which is why you feel less effort at the pedal.

It's similiar to flow through a tube, the larger the tube the less effort. Like an exhaust system, larger tubing and less back pressure.

So everything else you have is correct, but the effort part for the MC.

To put in non braking terms:

The larger the bore of a tube the less back pressure and the less hydraulic pressure at the other end. So with a larger bore you flow more, more easily, but get less force at the other end.


Unfortunately with many cars that have large volume requirements (to ensure full travel of the caliper piston) your sometimes forced to go with a large bore MC otherwise the pedal travel is just too long (imagine a MC in your SUV that's 80mm long, packaging and casting nightmare).
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