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Old 05-23-2002, 09:09 AM   #13
Scooby Specialist
Member#: 16215
Join Date: Mar 2002
Location: In a place with no laws, just "guidlines"
2002 WR WRX wagon


Originally posted by Jon Bogert
OK, so just using the fronts--as if the fronts are stopping 100% of the weight (which isn't far off), here's what I get:

Pedal pressure          100 lbs
Brake pad Cf            0.5	
Effective disc radius   0.36 feet
1/tire radius           1.07	

All up weight           1500	
Tire Cf                  1.2	
Stopping Force          1800	

Force ratio             93:1
Pedal ratio              6:1
Caliper to MC area      15.6 	
Caliper piston size     44.5mm
Caliper piston area     3111mm^2
x two calipers          6221mm^2	
MC area needed           399mm^2
MC diameter               23mm
So I should be fine with a standard 7/8" MC
You did it right!

Now keep in mind that if you want less pedal force (lower effort) then you will need a larger bore MC.

Now imagine that a 23.88mm MC is a commom size on many smaller cars. Now with out a booster it's nearly impossible to stop those cars. The only reason you can get away with a 23 is that the car is so light.
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Last edited by romanom; 05-23-2002 at 09:19 AM.
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