Sl500 Rear Brakes Locking On..

[davidsl500]

Picked up my car from the merc specialist after having a front wheel bearing replaced which was noisy. Mechanic suggested I keep an eye on the rear brakes as the edges of the brake discs were an orangey rust colour rather than the usual colour and he suggested that it might be due to sticky calipers.

6 Miles later the rear brakes locked up pretty solidly....

after about 30 mins it was possible to move again but within a quarter of a mile the drag could be felt once more. I got the vehicle recovered back to the specialist to look at.

The rear discs are worn but not to minimum and the pads are still like new. The specialist has reported that the caliper pistons are okay and moving freely and cant find anything out of place at the rear. He is now presently checking the rest of the hydraulic system.

Has anyone else had a similar problem? I have the feeling that the rear brakes are applying themselves .[/b]

 

[Arnie]

With piston calipers, it is only the pliability of the rubber dust shield boots that helps the pistons move away from the discs after releasing the brakes.

1.) make sure that these boots are OK and not broken (service kits are available)
2.) make sure there is no rust on the pistons.
2.) make sure that the rear of the pads are clean.
3.) Flush the brakes and change the brake fluid and bleed any air.

If the brown ring on he discs is only in the edge where the pads do not reach, this is OK, but it would be good to have the discs turned at the edge to remove the excessive lip. Otherwise, for peace of mind, change the discs and pads (as well as the above).

 

[davidsl500]

Thanks

Thanks for the reply. The specialist has stripped down the rear brakes and reports the calipers to be clean and free moving. Discs are only rusty on the extremities ie not near the pad contact area and all seals dust covers are in place and serviceable etc (it had a major brake overhaul in 2002). The hydraulic system has now been flushed out and system refilled and bled and the specialist reports all seems well - though he never felt the lock ups i experienced.

I shall be picking it up Thursday and hopefully all will be well. It is very disconcerting driving around waiting for the dreaded lock-up !

I shall be having new disks and pads all round in the next few months anyway, the specialist wants to ensure everything is okay first rather than overheating the new stuff if the problem continues.