Hot Brake

[palmerj]

My OSF caliper is running hot :mad:, used a laser thermometer on it compared to the NSF, it also has more brake dust on it.
Question, rebuild the caliper, seals and piston kit or just replace the whole thing? I'm ready for sods law to strike and the other one to go straight away afterwards.

2013 A4 Avant S-Line Black Edition with 1LT front brake calipers.

Also any steer as to the best place to get replacements from.

May thanks in advance as always.

Jools

[AndyN01]

Something relatively quick and easy to try first.

Try removing, cleaning, re greasing and replacing the guide/slider pins.

Chances are they are grunged up which is stopping free and easy release leading to the caliper sticking.

This might not be enough but I'd certainly give it a try.

Good Luck.

Andy.

[palmerj]

Andy
Thanks for the suggestion. I have already done as you said which seemed to stop it for a while.

Jools

[AndyN01]

Thanks,

Just thinking aloud here and you may well have already checked all these.....

Are the pads free in their hosing allowing them to move backwards/forwards easily?

I've known pads to be forced in past crud & corrosion and be pretty much locked in place. Not helpful!

Has the rubber boot seal on the piston itself become damaged allowing crud in which has, in turn, compromised the movement (retraction) of the piston itself? In the past I've had success with spraying some silicone spray inside the seal to give some lubrication to the "O" ring on the "none - pressure" side of the system. The pressure side is, of course, constantly lubricated by hydraulic fluid.

It's worth checking if the disk is warped to the extent that it's constantly forcing the pads apart creating the heat you're experiencing.

Maybe a wheel bearing is on its way out which is giving the same symptoms?

If none of that works then I can't see any other option except either a complete strip down & rebuild or a new caliper.

Good Luck.

Andy.

[Catlazer]

I had this on mine earlier this week. Turned out to be caliper seized so had to replace caliper & discs & pads. So went whole hog & got both front calipers done.

[Jasonj1965]

Same thing happened to mine just pulled apart copper greased sliding pin and other assembly all good now no problems
Easy fix


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[palmerj]

Hot Brake Update
It's been a while since I first asked for advice. I thought I'd better close out the thread.
I got a caliper rebuild kit from Biggred I ended up speaking to them on the phone after their on line ordering system stalled for some reason, they were very helpful, I would recommend them to anyone who finds themselves in a similar position.
I didn't mess around with one and bought a double caliper kit including new pistons at under £40 it wasn't worth the effort and I thought if one is binding the other might not be too far behind.
I removed the caliper and stripped it. The piston bellows had slipped off the caliper and rust had started inside.
36144
I guess the rust then worked its way between the caliper body and the piston stopping it returning once the brake pedal was released, friction then did the rest!
I then found the piston was actually very slightly oval as it would wobble back and forth on the high spots even after removing it and removing the piston seal. I think the heat after the initial sticking must have misshapen it over time.

Any way replace with new pistons and seals, bled etc. Did the other side the next evening and haven't looked back.

The whole thing was far less stressful than I expected it to be.