D
Don-lo
Guest
I agree that a clean caliper assembly with fresh fluid and good lines are essential, but since this problem surfaced after removing the forks and wheel it is probably a problem of slightly bent forks, axle and alignment. The discs are essentially perfect "T"s coming out from the wheel, and forks need to track true to align. A small deviation will load one end of the brake pad, and thus one side of the piston, which does not easily move it. Leaving the caliper bolts less than tight is a way to compensate for this slight deviation. You can usually align the forks if the bend is not too bad. First, loosen the fender and any fork brace. Then, with the front end slightly in the air, loosen the top fork-holding bolts on ONE fork. This should allow you to spin the fork top. Look down the fork as you spin it and note if the wheel and forks are moving side to side and front to back (and probably binding as they go). I would choose the middle/ back location to set the forks. Make sure the fork top goes up to where you set them, tighten the fork-holding bolts, and then repeat this procedure for the other fork. Badly bent forks should be replaced, of course, and they will usually be accompanied by a bent lower triple clamp. Fork alignment then needs to be done (pumping them and retightening).
A bent front axle cannot be overlooked either.
A bent front axle cannot be overlooked either.