Sticky brake caliper.

My 45 has started suffering from a sticky front o/s brake caliper. It sticks quite hard and gets very hot indeed!



The first thing I did was just to lever the pads to force the piston in a bit, and make a bit of clearance, so that I could check that the pads weren't sticking in the carrier and the sliding guide-pins were free. All seemed OK but the problem remained, so I have swivelled the caliper out of the way and taken out the pads and shims, but I can still find nothing definitely wrong.



I thought there might be some damage to the shims, but the shims on the outside of the pads, and the shims that fit where the pads locate in the carrier seem perfectly OK. However the round shim shown in the manual as fitting to the piston is absent and appears never to have been fitted. The piston is not seized - I can move it inward with heavy thumb pressure, but it is quite stiff. The dust seal doesn't appear to be torn, but it is not in its groove all the way round.



The disc is quite scored, and I think I will probably need to replace both before the next MoT, but I've checked with a dial gauge, and the run-out appears to be only about 1 thou, so within spec.



Does it sound like the problem is with the piston, or should I just clean, grease and reassemble and try it again?

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