In a message dated 6/24/2005 12:34:09 PM Eastern Daylight Time,
eanderson@carolina.rr.com writes:
Hi Georges,
Yes, it was you that suggested the apex seal as the possible
culprit. Actually, the flash point of the brake fluid used is only 240F!
Not much above the boiling point of water! The brakes had been used -
but, nothing abnormal, I did not make a panic stop or such, I have put on the
binders much harder and never had a problem. But, it had to be the brake
pads and I can easily see 240F of heat being generated by them.
Also the brake pads always ride touching the rotor - nothing to hold them
back. I guess this does not normally cause a problem.
Ed
The single piston slider type calipers rely to some extent on rotor runout
to help knock back the pads, once pressure has been released.
In aircraft applications this does not work worth a damn because the wheels
are so light and are turned over so little. Also the slider mechanism has so
much friction that the non piston pad almost always wears faster than the
piston end pad. A plane used often has little difference in pad wear. Also when
applying pressure the "O" ring seal will deform slightly as it is pushed along
with the moving piston.
When pressure is released, the deformed "O" ring returns to normal and
retracts the piston.
This may not move the slider end of the caliper at all. If there is some
runout in the rotor, the rotor will knock back the slider end pad slightly. Even
side loading the wheel will deform the assembly enough to knock the pads back.
If there is no flex line to connect the caliper to the fixed brake line,
then the aluminum brake line must flex with each brake application. Aluminum has
a very short fatigue life. The tighter the bend radius, the lower the pressure
rating, and the shorter the fatigue life.
A racing tip. Fresh "O" rings keep the brake drag down.
Lynn E. Hanover