Brake Fluid / Rubber Compound Compatibility


Hello Sam:

I have not repaired Airhearts, but they must make a rebuild kit, and if the
cylinders have pitted surfaces, they need to be honed just like any other
brake cylinder. I have done lots of Triumph car slave and master cylinders in
this way. Gasket seals, compression seals, cylindrical cup seals - what else
is there to do? How about use the appropriate rubber kit for the appropriate
brake compound? According to published Airheart literature:

"...Make certain that the master cylinder you are using has the correct
seals to be compatible with the hydraulic fluid being used in the braking system.
Master cylinders with EPR seals are designed for use with automotive brake
fluid which meets the standards of SAE-J-1703 and DOT-3. Master cylinders
with Buna-N seals are designed for use with mineral base "Red" hydraulic fluid
which meets the standards of Mil-Spec. MIL-5606..."

There is better than a good chance the cylinders are fine but which have at
some time been cross-contaminated with the incorrect brake fluid.




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