Overheating front brake

I have an ongoing front brake problem. The brake fluid heats and expands forcing the pads to bind to the disc. The bike slows to a halt. I have to release the fluid pressure by cracking open the bleed nipple on the caliper.
I have renewed the master cylinder and caliper piston seals. The caliper appears to slide on the small caliper shafts but there does seem to be some play in one of the shafts.
My next move will be to replace the brake hose but I can't see that curing the problem.
Does anyone have any ideas?

the hose can be collapsed (sp) had that happen on a race car once, on that one we rebuilt everything and after a short run the right front was grabbing, it would lock the wheel up in the pits, so yes it may be the hose on the inside that is giving you the problem

After rebuilding your caliper and master cylinder did you use fresh fluid from a sealed container? It sounds like you have water in your system that heats up and begins to expand.

Later, Doug

check the master cylinder pressure return/release orifice. it is a tiny passage inside the master cylinder and needs to be clear. what you look for is the fountain squirt out of the reservoir when the brake lever is squeezed then released.

the other option I can think of is that the brake caliper piston is sticking inside the caliper bore and not relaxing after pressure is released.

the last thing is if the brake lever has a threaded bolt as a adjuster to the plunger and the adjustment is too tight.

good luck

I can only find one drilling between the reservoir and the master cylinder. There is what looks like a drilling but appears to be a casting spot with muck in it. Could this be the return orifice?
There is no adjuster between the lever and the piston.
I renewed the caliper seal recently and the piston seemed free.

"appears to be a casting spot with muck in it."

Yep! If that bleed is blocked off the system can't take fluid back from the caliper.

kzcsi