Quote:
Originally Posted by pdxmotorhead  You need to bleed the brakes after every track session, if you want to keep brake performance at peak. You should also check the dust seals on your calipers for baking. The rubber parts of the caliper do get baked hard on track, sometimes after a couple days the rubber soaks up enough fluid to soften them and they work better.. But if I'm tracking a street driven car I'm going to regularly tear the calipers apart and replace the O-rings, and the dust seals.
The dust seals are optional on a track only car, I don't even install them on race cars.(They just bake away anyhow...)
Aslo when you change your brake pads, and your compressing the calipers, open the bleed screws so
you don't force grungy fluid back into the ABS pump and master cylinder. Instead just let it run out the bleed screws into a catch bottle.
later
Dave |
Here is what a Belgian brake engineer writes:
The one-time longer pedal travel you experience the first braking manoeuvre after a quick run is caused by the brake pads getting retracted from the hot brake disc (by a rubber inside the caliper). This is what is supposed to happen, otherwise your brakes would be dragging during driving. Next thing that happens is the brake disc cooling and getting thinner a couple of fractions of a millimeter. The slightest difference between disc and pads creates a long pedal travel. (someone should calculate the travel ratioŽs to have some impression, or you could try putting a thin feeler guage between your pad and disc, retract it and press the brake pedal, youŽll notice the longer travel)
The extra effort is simply caused by the lower friction of the pad, which has been affected by the high temperatures. This is only the top layer and will disappear over time (gradually, as there isnŽt a line to draw of where the lower friction part of the pad is)
The prolongued travel is caused by a increased compressibility of the top layer of the brake pad (again fractions of a millimeter), also caused by the heigh thermal stress on the pad. When this layer had worn off, the longer pedal travel has gone."