spewing rear brake

[Steve@Motowest]

If the bleeder fitting in the caliper is leaking remove it and check it closely. They can be easily crushed if overtightened - look at the passage hole in the side of the bleeder, is it round or oval. It should be round, they turn oval as they are being crushed or it might be smashed flat. Either way replace it.

Those finned coolers that mount on the master cylinder are near worthless, they are mounted too far away from the heat generated in the caliper to do any real good. There are some heat-sink type coolers available that attach to the caliper, that could help a little. And use the Motul 600 brake fluid, it has a very high boiling point.

We are working on a fluid circulation system (like they use on race cars) that will circulate the fluid through a cooler and back to the reservoir each time the pedal is pumped. This is the only real way to deal with overheating fluid.

[gasgasman]

Try the Ford Motorcraft brake fluid.
It is DOT 3 with a minimum dry boiling point of 500 °F (260 °C)



There was a company that would machine your caliper piston and install a Teflon button where the pads ride to reduce heat transfer to the caliper.

[LAWMAN]

thanks for the advice! I have cut off the bottom of the stud but did not get to finish adjusting the pedal. if I have time by Sunday, I'll try to find the exact source of the spew, but I may just have to ride it as is on Sunday. I think it will help a lot to have the pedal lower, we will see.

thanks again for all the help.

[iancp5]

Originally Posted by gasgasman

Try the Ford Motorcraft brake fluid.
It is DOT 3 with a minimum dry boiling point of 500 °F (260 °C)



There was a company that would machine your caliper piston and install a Teflon button where the pads ride to reduce heat transfer to the caliper.

On my KTM they have a piece that pushes into the piston on the rear - wondered why, now I know.

[LAWMAN]

status report: cutting the stud & raising the pedal seems to have solved the problem.

for the benefit of future generations of GG newbies, here's how I did it: I cut 5-6mm off the stud with a Dremel tool & cut-off wheel. I forgot to leave a nut above the cut, so I cleaned up the threads a bit with a die, nothing to it. then I adjusted the pedal as low as it would go & went riding at a gnarly place in the Ozarks, & no problems (so far). I'd get it a little lower if I could, but I think it will do.

thanks to all for the help!

[LAWMAN]

Well, here's the late final:

I thought I had this fixed, but no joy--it would still get hot after a while & boil, altho it was better w/the pedal lowered--it took me longer to boil it. I knew that something mechanical had to be wrong w/it, but I could not tell what it could be & did not have the time to use trial & error replacing everything 1 part at a time.

so I eliminated all the variables at once--I replaced everything behind the master cylinder (since I'd already had it rebuilt) where fluid could be leaking. this entailed the hose, slave cylinder & bleeder valve.

& that fixed it, now it works great. thanks to all for the advice!

John

[GMP]

Yes, I cut the studs for a lower pedal as well. Organic pads(less heat transfer) and a solid rotor(less wear on the pads) help as well.