Been a while since I was here. Problem: I changed the front rotors on one of my bikes to Braketech floating ductile iron cryogenically treated ultralight rotors. After doing so I had a big problem with the front brake lever losing movement, as if the system fluid expanded, and after several miles the front system completely locked up and the brake lever would not move.
I first re-aligned the axle by loosening the fork pinch bolts and the axle while bike on ground, roll bike and hit brakes, roll bike hit brakes, etc., and then tighten one fork tube and tighten the axle end and then tighten both pinch bolts. This did not fix the problem.
Next I removed the calipers, dismantled them completely, cleaned them, inspected the pistons and casings for any defects (found none), replaced the inner and dust seals, reassembled, and was able to get the pistons to withdraw all the way, whereas before they would not (the dust seals were gooey, so that was a slight problem). Unfortunately, the problem was still there. Even if I bled out some fluid (more than once).
Leaving the bike in the sun just caused the problem to occur with no driving. The heat caused the lever to completely lose any movement and the brake shoes became pushed against the rotors so hard I could not move the bike. I again bled the fluid, and the problem simply reappeared again, even after I bled the fluid, until I finally decided to take all the fluid out, at which point the problem was gone and the rotors were completely free.
Any suggestions? I have talked to Brake Tech. They walked me through some measurements to make sure I had the correct shoes on the calipers (they sold me the shoes), and they were correct and there is plenty of room between the rotors and the shoes. I took off the master cylinder to dismantle and inspect it, but if it is like the calipers, I am not going to find anything. I hope I do, but I would like to hear from anyone who can shed some light on this problem. Thanks.