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 Posted: Jun 24, 2019 05:38AM
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US
The repair/replace question has to be answered after you take the caliper off the car, extract the pistons, and look inside.

Brake calipers do not seal on their bores but on the square-cut o-ring grooves in those bores.  Therefore, you can often clean up a caliper and its bore, fit new pistons and seals, and the caliper is fine.  It all depends on the rust and pitting in the square-cut o-ring grooves.

Doug L.
 Posted: Jun 24, 2019 04:25AM
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I will try to get a picture later today or definitely tomorrow, I didn’t have the time to pull the wheel off.


If it would be the piston that is stuck, will that require replacing the caliper, or can I fix that some other way?

Thanks!

 Posted: Jun 23, 2019 04:50PM
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 The photo will be helpful. It may be that your outboard piston and therefore the pad is stuck “open.” The reason you might not notice braking asymmetry is that your inboard caliper piston is working fine and the whole inboard pad is making contact with the inboard side of the rotor. The water/dust shield covers the inboard side so you cannot see much of it without taking the rotor off ( or the shield). My guess is if you look at your inboard side of the rotor you will find that it is fully “swept.” The two sides of the mini caliper pistons can move independently. I assume you have standard two pot type

 Posted: Jun 23, 2019 11:41AM
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Can you post a picture showing what you are concerned about?

Doug L.
 Posted: Jun 23, 2019 09:27AM
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So today I had a closer look at my front brakes on my 88 Cooper, and noticed that on the left hand disc, there was only a very small strip of wear. That is, it looks like only a small part of the disc is being used, all the rest of the disc has surface rust and spots on it like you see on areas of all brake discs that are not in contact with the pads.

The RH side has this somewhat less. I do not really notice any pulling to one side when I am braking but now am wondering what could be causing this?