A discussion of brake problems
Ever since I have had the SRT I felt that the brake pedal feel was worse than my old NA, if both cars use the same master cylinder I know why.
I had thought that a larger master cylinder bore would improve the brake pedal feel and possibly improve braking, this is patently not true I find and would lead to worse braking due to the extra force required at the brake pedal. See the explanation below.
The pedal length from the pivot and the master cylinder push rod distance from the pivot are designed to give the best overall results.
Soft pedal can be caused by air in the brake system or water in the brake fluid turning to steam when the brakes get hot.
Excessive pedal travel can be caused by too much play in a wheel bearing, sticky calipers and too much free play in the pushrod that actuates the master cylinder pistons. Our free play is not adjustable like many other cars brake pedal. Some free play is necessary to allow the expansion of the brake fluid as it warms up otherwise the fluid expansion would start to move the caliper pistons.
In this diagram if the master cylinder had a bore that was one square inch then there would be 6lb/sq.in on the caliper pistons.
But if the master cylinder was increased in bore size to two square inches then there would be only 3lb/sq.in on the caliper pistons and require twice the pressure on the brake pedal.
So increasing the MC size has an adverse effect on braking.
During braking the seals in the caliper piston grooves distort toward the rotor, when the pressure is released the distorted seal returns to its normal shape and pulls the pad away from the rotor by a small amount. The area of the seal that is touching the bore has a resistance to moving, so this area stays where it is and the seal in the groove moves distorting the seals shape, when the fluid pressure is removed the seal returns to its original shape and forces the piston away from the rotor.
If the piston is sticky in its bore the pad rubs against the rotor causing premature wear.
To be continued.
Last edited by onehundred80; 04-10-2018 at 10:04 PM.