bad caliper?

[kevinkay]

had the right real caliper sticking, heating up - TONS of brake dust.
replaced it with a rebuilt $62 caliper found at a local independent truck parts store (they ordered it and got it next day). Fit, looked like a new piston, only discrepancy was the bleed screw was 1 mm smaller wrench size than the rest.
Next week, ordered rebuild kits for remaining 3 rotors $25 a wheel - rebuilt and heavy flushed and bled system.

fast forward 1 year:
driving slow speed in a parking lot noticed awful "grinding" noise with rotation of wheels. (fist panic is bad bearing and I HATE doing bearings).
Stopped, checked it out - again right rear caliper is HOT, smells and rotor looks too shinny. Let car cool for 2 hours, drive home about 1 mile, no noise, that wheel hotter than the rest, but not overheated.

I ordered a new rotor FCP $300 it should come tomorrow.

Anyone have bad experience with rebuilt calipers? I have read that once a caliper heats ups/cooks that it should not be rebuilt?? (and assuming the one i bought had been cooked)
Should I fear an issue with master cylinder this being the wheel furthest and not getting enough pull back pressure?

OR - you get what you pay for - $62 for the rebuilt caliper?? when the rebuild kit costs $25 re-using the old piston.....

THANKS

[Scott ZHP]

What was included for $62? Just the caliper, or the carrier too? Sticking calipers often mean bent or rusted carrier pins. These are about $8ea. I replace the bushings too, they're about $5.

Your issue could also be totally unrelated to the caliper assembly - have you carefully inspected the brake hose? With age, they breakdown/collapse internally and sometimes let fluid flow in, but not back out, causing the caliper to grab and not want to release.

[Ricky Bobby]

^ with Scott, replace the wear items on the carrier as well if installing a rebuilt caliper - if its an A1 Cardone I think they only rebuild OEM calipers - I prefer to stay away from the "New" chinese aftermarket

I would also do all 4 hoses for good measure - I'm due to overhaul the brakes at the 13+ year mark and its on my to do's for spring, get some nice coated rotors, better pads, and some stainless hoses and address the calipers if needed at that time.

[upallnight]

Although stainless steel hoses are nice to look at most of them are for racing only and are not DOT approved. I have them on one of my Lotus, but I race that Lotus more then I drove it on the street. Also one time the positive cable wore through because of the location and the stainless steel hose was a perfect ground path for the battery current. The hoses got really hot and melted the rubber inside the stainless hose. Needless to say you don't have any brakes at that point. I would never install stainless steel hoses on a Street car.

[kevinkay]

THANKS-
did not replace the carrier, just caliper and new guide pins, (and yes, I do/did grease them VERY lightly -even though I not supposed to?)
AND I did replace that wheels rubber hose for another $65 from the dealer
This was all done last year when I was away from home and needed parts quick.

going to pull the wheel off when I get home and get a better look, it hit me maybe the pad cracked, thus the grinding noise and heat?

[upallnight]

I had a grinding sound on one of my car, took it in since it was still under warranty and the mechanic told me a rock got lodged between the rotor and the wheel back plate shield.

[StephenVA]

Great questions and answers. Unfortunately we can not look at the caliper and rotor from a far (Pics don't really give you an idea of what is really happening).
Rear brakes have the parking brake inside so there is a little more complexity involved as far as problem diagnostics are concerned.
One of the fastest ways to confirm caliper hanging up ("sticking", i.e. piston not retracting after pedal release) is to measure rotor temp after a road test. left to right, front & rear. Any IR tester will confirm. TEST HOT, not after 2 mins of driving.

Next pull the wheel and inspect the brake material and calipers - pad wear the same L to R? Any foreign material in between the rotor and splash shield? caught in the caliper? Pad wear on one pad (outer pad for example is a sure sign of caliper not "floating" back on the pins but binding and allowing one pad to be in contact when the brake pressure is released.

In any case both calipers should have been replaced or rebuilt as you did. The question I would have are they now matching in bore size. The bleeder screws are replaceable and can have the wrench flats different but the screw threads the same. (Not an issue whatsoever) Check the casting numbers to confirm if they are rebuilt/new. Ours use ATI brand calipers OE on most applications. Bleeding the brake fluid every other year prevents most caliper issues on BMWs.

Do a little visual inspection and you will see what if anything is happening.

No fluid leaks, Pad contamination, etc? RIGHT?

Helpful?

[kevinkay]

EXTREMELY helpful - as is everyone who has replied.

no fluid leaks.

YES, did the rotor heat test with a skin burn to prove it. Using just my hands this rotor, caliper, wheel was MUCH hotter then the rest.

I pulled the wheel and like "upallnight" pointed out the shield is so close to the rotor I thought it was rubbing, but no visible scratch marks on the rotor.

I was very surprised the condition of the pins after 1 year, yet they were not "stuck". The piston looks very expanded, yet I was able to wiggle the caliper off without compressing. I could not compress the piston with my hands only (questionable if it can be hand compressed?). I did not compress it with a "C" clamp as I am going with my original diagnose and will precede to replace this caliper and did not want to possibly push back in any foreign material that may have worked its way to this caliper and blocking the return.

I pulled the rotor to check if any problems with the emergency brake shoe or a stone in there, it looked fine. (hate those emergency brake removal "star wheels", and then when the wheel is off and you can actually see it - its so easy and makes sense).

snapped some photos, the rebuilt caliper is stamped BMW, but I will feel more confident when I know I am replacing it from a reputable dealer.

I may make it a yearly commitment to pull the pins yearly and wire brush them. Unless someone tells me the light smear of grease caused them to gunk up?

Why I am not completely confident is because the noise -grinding. My understanding and last years binding rotor wasn't noisy, just heat, and tons of brake dust. I guess I will see tomorrow with the new caliper.

THANKS!

[Ricky Bobby]

I believe those pins were intended to be installed dry for a reason.

Jeff (JCL) chimed in back in the day on why they should be on our cars, as opposed to some that like a light coating of grease.

[srmmmm]

The rust on the assembly (especially the piston) is surprising for just one year's use. Almost speaks to potential contamination inside the caliper itself. As for greasing the pins, I've always used a hi-temp silicone grease on the caliper bolts/pins on all my vehicles without any issues.

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