rear brake sticking - The Unofficial BMW M5 Messageboard (m5board.com)

doc_76544 · 31st March 2006, 08:58

hey all,
i've noticed that after a short maybe 15-20KM drive my drivers side rear brake gets really hot, enough that you can feel the heat from it. there is also excessive brake dust on the wheel from this and it appears that my disk is getting quite worn down quite quickly. now i know i'm most likely going to have to replace the pads and rotors in the rear now as i would never only change just one on a set. but what could be the cause of this? perhaps a stuck piston? or perhaps the little pad slides are gummed up? would i have to replace the caliper as well or can it be un stuck easily?

thanks
shawn

corneredge · 31st March 2006, 09:37

I've had this happen on older bimmers. Its most likely a stuck caliper. In the short term as a fix I've been able to "work" the piston free by removing the caliper and using clamps to work the piston back and forth. I bleed the brakes, and its ok for a short while. Depends on the exact problem.

Correct fix is to rebuild the caliper or get new.

-Russ
'94 M5

M540i LE · 31st March 2006, 09:56

I agree that it sounds like a sticky piston.

Best solution is to buy a rebuild kit (cheap), remove the calipers (relatively easy) and either rebuild them yourself or have someone elsedo it. In either case, much cheaper than a new caliper. Should get away for under 100 Euros in total.

Good luck

doc_76544 · 11th April 2006, 07:56

update: i parked my M5 for a while due to this problem and the lack of funds. when money came i ordered all neccesary parts two rear disks, set of pads and all the other little parts but not the caliper. i figured maybe i could inspect it and possibly free it up with lubrication and a little work. WRONG. after the M was parked for about a week and all the parts came in i went to grab it and take it to the local u-do-it place with lifts and all that. jumped in, warmed her up a bit and stuck it in first as usual and it took a little more pedal than usual to make her move. that caliper was frozen to the disk, it freed up but not without a loud crack noise. so since it was only like 200 meters to the lift place i drove it there, tossed it up on the lift and took everything apart i of course did the easy, unfrozen one first no problems, got to the other side and took it all apart, took the caliper off to realise the piston was completely corroded and unmovable. so i put the car back together less caliper and pushed it out of the lift area to park it as the lift place charges by the hour. and went back to the parts place to see if they had rebuild kits and or a already rebuilt one, no rebuild kit but they were able to order an already rebuilt caliper for exchange so i did it that way, i'm still waiting on that part to come in though hopefully it will be in tonight and i can finish my car and not have to ride my bicycle to work in the rain.
Shawn

M540i LE · 11th April 2006, 08:10

Doc

Bad luck. At least it was the more generic rear caliper (which is common with the 540i) and not a far more expensive - M5 only - front caliper.

Hope it all gets sorted soon.

Kind regards

Quote:

Originally Posted by doc_76544

update: i parked my M5 for a while due to this problem and the lack of funds. when money came i ordered all neccesary parts two rear disks, set of pads and all the other little parts but not the caliper. i figured maybe i could inspect it and possibly free it up with lubrication and a little work. WRONG. after the M was parked for about a week and all the parts came in i went to grab it and take it to the local u-do-it place with lifts and all that. jumped in, warmed her up a bit and stuck it in first as usual and it took a little more pedal than usual to make her move. that caliper was frozen to the disk, it freed up but not without a loud crack noise. so since it was only like 200 meters to the lift place i drove it there, tossed it up on the lift and took everything apart i of course did the easy, unfrozen one first no problems, got to the other side and took it all apart, took the caliper off to realise the piston was completely corroded and unmovable. so i put the car back together less caliper and pushed it out of the lift area to park it as the lift place charges by the hour. and went back to the parts place to see if they had rebuild kits and or a already rebuilt one, no rebuild kit but they were able to order an already rebuilt caliper for exchange so i did it that way, i'm still waiting on that part to come in though hopefully it will be in tonight and i can finish my car and not have to ride my bicycle to work in the rain.
Shawn