How do you check brake calipers

[Kibokojoe]

Need to know how to check brake calipers. Lost a rotor last night to a new set of semi metalic pads. Pads were installed on Sunday and the rotor and the exterior pad on the left side of the car are destroyed with less than 2 hours of driving. My thoughts are caliper piston could be sticking or that the caliper is not sliding on the pins. How do you check both of these for proper operation?

[yaofeng]

A C-clamp.

[Kibokojoe]

I think I may have found my problem. I normally hi-temp grease the caliper pins but looking on this forum I have discovered they should be installed dry, or at least using a specialized coating. I bet the grease has caused the pads to bind up. I will pull the brakes tonight and do a through cleaning. New rotors and pads with a clean caliper should do the trick. I will look into the pin lube though

[whiskychaser]

Need to know how to check brake calipers. Lost a rotor last night to a new set of semi metalic pads. Pads were installed on Sunday and the rotor and the exterior pad on the left side of the car are destroyed with less than 2 hours of driving. My thoughts are caliper piston could be sticking or that the caliper is not sliding on the pins. How do you check both of these for proper operation?
With no pads in, you should be able to move the caliper on the pins by hand. The piston can go in crooked and jam and I use a G clamp push it in. I'd leave a small gap between the clamp and the piston and press the pedal. Then check to see if I could back the piston in again easily. If thats ok, I'd chuck the old pads in and stand on the brakes to see if I could make it jam-no point messing up a new set unless you are happy. HTH

[Kibokojoe]

Will give it a go. Parts are suppose to be in this afternoon

[Bill R.]

even though you're supposed to put them in dry and clean a number of people here have greased them in the past without the problem that you had

Even with a sticking caliper i haven't seen one kill the pad in only a couple of hours, it usually takes weeks and is pretty obvious by the pull on the steering wheel




I think I may have found my problem. I normally hi-temp grease the caliper pins but looking on this forum I have discovered they should be installed dry, or at least using a specialized coating. I bet the grease has caused the pads to bind up. I will pull the brakes tonight and do a through cleaning. New rotors and pads with a clean caliper should do the trick. I will look into the pin lube though

[632 Regal]

Back looking at this stuff for todays issues. Amazing info.

[shogun]

we had some cases especially on E32 750 with the H31 brake unit in our warehouse which were long time parked, that the brake calipers were stuck. The problem is the brake master cylinder, inside there are some seals and a bakelite ring, this bakelite ring 'swells' by age and then the master is stuck at some point. I know of some people which has disassembled the brake master and 'polished' a bit off the diameter of the bakelite ring.
Here a pic how it looks inside a H31 brake master cylinder, probably the others look same / similar

[genphreak]

we had some cases especially on E32 750 with the H31 brake unit in our warehouse which were long time parked, that the brake calipers were stuck. The problem is the brake master cylinder, inside there are some seals and a bakelite ring, this bakelite ring 'swells' by age and then the master is stuck at some point. I know of some people which has disassembled the brake master and 'polished' a bit off the diameter of the bakelite ring.
Here a pic how it looks inside a H31 brake master cylinder, probably the others look same / similar

Amazing. What a find. I guess if you strip the master cylinder down and the ring is binding... its staring you in the face. eek! Can it be that the wrong fluid was used?

[genphreak]

kibokojoe, re the binding caliper, I doubt the grease is the culprit*, IMHO it isn't used because the grease only attracts dirt which will cause abrasion, even allow larger things to stick potentially (?)

* unless you hit some sand/fine debris which somehow got lodged in a piston caliper and caused it to bind. Never seen this happen.

[shogun]

Can it be that the wrong fluid was used?
no, the problem is the age of the material of that bakelite ring. Many E32 750 and E31 850 owners have the same problem. But no big problem, replacement is available even from aftermarket and remanufactured ones for less than $200.
ATE once sold the bakelite ring as well as the seals as single spare items, but no longer available, they now only sell cpl. reman ones.

[genphreak]

no, the problem is the age of the material of that bakelite ring. Many E32 750 and E31 850 owners have the same problem. But no big problem, replacement is available even from aftermarket and remanufactured ones for less than $200.
ATE once sold the bakelite ring as well as the seals as single spare items, but no longer available, they now only sell cpl. reman ones.

Sorry @shogun; I was talking about the caliper pins- but replied to your post re the master cylinder. Interesting comment, any idea where to find the CPL ones? If they are not a good option, can a replacement in teflon or something be machined up and used? BUT: It may well be that the bakelite the best to prevent jams and leaks over time, heat and use.