Rear brakes binding after new discs/pads
09-18-2021, 05:14 PM
#1
Junior Member
Thread Starter
Rear brakes binding after new discs/pads
Hi Guys
Long time lurker, first post!
I thought other owners might find this useful: Having changed the rear discs/pads they were getting extremely hot because they were binding - both side of the car. The (phenolic) pistons appeared to have gone back into the calipers pretty easily but I decided to investigate further by dismantling them. I cleaned the caliper and inserted the piston (without seal) - it went in perfectly until the last 1/2" and then stopped. I measured the pistons at the top and bottom and found that they had become tapered - effect of heat on the plastic over 80k miles? They were wider at the top - next to the pad. The difference in diameter was 0.002" but it was enough to wedge the piston in there. I put the piston on a mandrel on the lathe and "honed" it by hand using 1200 grit wet & dry until the taper was gone. The brakes are now working normally again. I have dismantled 4 calipers now and they were all the same.
Hope this is useful to others
Long time lurker, first post!
I thought other owners might find this useful: Having changed the rear discs/pads they were getting extremely hot because they were binding - both side of the car. The (phenolic) pistons appeared to have gone back into the calipers pretty easily but I decided to investigate further by dismantling them. I cleaned the caliper and inserted the piston (without seal) - it went in perfectly until the last 1/2" and then stopped. I measured the pistons at the top and bottom and found that they had become tapered - effect of heat on the plastic over 80k miles? They were wider at the top - next to the pad. The difference in diameter was 0.002" but it was enough to wedge the piston in there. I put the piston on a mandrel on the lathe and "honed" it by hand using 1200 grit wet & dry until the taper was gone. The brakes are now working normally again. I have dismantled 4 calipers now and they were all the same.
Hope this is useful to others
