Quote:
Originally Posted by spk74
Are the ceramic pistons are breaking because of heat, pressure, or both?
If you use street pads (like HP+) that lose effectiveness at a lower temperature (compared to track pads) and have to mash down on the brake pedal, could that added pressure break the pistons? Watkins Glen has some serious braking zones (i.e. where the NASCAR guys have warped the track surface). But could you have been better off (would the pistons be OK) if you'd used HT-10's or a DTC pad?
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The ceramic piston caps reduce heat transfer into the caliper pistons. In doing so, they also retain a higher temperature on the pad side, so they run hotter themselves. It's a tricky thing to get heat transfer rates correct enough so that each different material does not exceed its maximum temperature, yet also uses the thermal conductivity of other parts to cool the whole lot. We need to remember that the aluminum caliper does a bit of work in cooling the brake pad. Ceramic piston caps somewhat reduce the effectiveness of that function. If you can cool the pads from behind (like is done with racing calipers), then slowing the heat transfer into the caliper is a good idea. But when the heat has nowhere to go, you run the risk of failed components.
But to directly answer your question, it is the heat that kills them.
Chris