I am using 4 new GM Metric calpers with a new 1 inch bore, single piston Wilwood master cylinder. I am using stainless steel braided teflon brake lines. I am using a 7 to 1 pedal ratio. This is a combination of components that I have used successfully on 3 previous cars. I am sure that the calipers and master cylinder are properly bled. Here is the problem. I have a soft pedal with everything hooked up. If I block off the rear brakes and use only front brakes the pedal is much better... If I block off the front brakes and use only the rear brakes the pedal is much better... If I hook up all 4 brakes, I am back to a soft pedal.. ????? Any help appreciated! mac miller in INDY
Might have to go to an 1 1/8" or larger bore master. Sounds like you aren't moving enough fluid to activate all 4 calipers.
Sounds like your not moving a sufficient volume of fluid to activate all four calipers. I'm with frozenmerc. Go up in bore size to move more fluid.
Check to see if the callipers are perpendicular to the disc. There could be pad knock off due to the brackets flexing
Didn't end up with low drag calipers by mistake? Those will give a real low pedal without the correct quick takeup master cylinder.
Are you using the braided teflon lines for all of the brake lines or do you have hard lines also? There is some give in those lines that could cause a volume problem if long lengths are used.
Is the MC above or below the calipers? If it is below do you have residual pressure valves in place? Also are the calipers matched to the thickness of the rotors? Some aftermarket kits require a spacer between the pad and caliper to compensate for a rotor that is thinner than the caliper is designed for so the caliper piston is not over extended.
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