3.0d, Rear brake disc heating up (right only)

[alexxxa]

Hi there guys.
So, I've been having this problem for a while, and I wanted to ask for advice before I start changing everything, part by part.

As the title says, my rear right brake disc is heating up more than the rest of them. It gets to be even 50-100 degrees Celsius warmer on certain spots (if I measured well, it is after the caliper) than the left one.

If I drive longer routes (let's say, 30+ min drive), it gets hot, so you can hear squeaking and scraping noise coming from the rear right, and the right wheel gets warmer than the left (of course, you can't touch the brake disc itself).

Important to mention: I changed handbrake pads (ATE), brake discs (ATE Power), brake pads (ATE), and brake fluid (ATE Typ 200 DOT 4) six months ago.

I'm suspecting (and hoping) it is just the right rear caliper.
However, when you lift the car, put it in neutral, and spin the rear wheels by hand you don't feel much of a difference. We cleaned the caliper again, but no difference.
Also, I eased up the handbrake pads on the right side (right cable also), so it seems it's not them (plus, the hottest spots I measured are after the caliper. Before the caliper the temperature seems to be normal).

What do you guys think?

1. Would you also first go with changing the caliper?
2. Or maybe the pads, that is the one on the right is faulty?
3. What is the chance that the brake disc came faulty, and is slightly bent?
4. Could it be the wheel bearing? But I don't have any other symptoms.
5. Something else?

I appreciate your suggestions before I start blindly changing part by part.

[80stech]

I would say it's a good bet that the caliper is starting to seize/drag. Did you notice anything when you spread the calipers to install the pads?? Are you sure there is no air in the hydraulic system? Caliper pins are good? A warped or bent rotor won't cause that problem. Wheel bearing would make lots of noise long before anything else.

[Henn28]

Originally Posted by 80stech

I would say it's a good bet that the caliper is starting to seize/drag. Did you notice anything when you spread the calipers to install the pads?? Are you sure there is no air in the hydraulic system? Caliper pins are good? A warped or bent rotor won't cause that problem. Wheel bearing would make lots of noise long before anything else.

Agreed. Likely need a replacement caliper, or time to rebuild the one you have. Check the brake lines to the caliper too. I'm not sure if they degrade internally like other cars I've had, but they could be shedding crap into the caliper internals that is causing it to drag. One of my jeeps had the same issue your X is having several years ago and it took a new caliper and brake line.

[Bdc101]

If it gets that hot I would expect the car pulls to the right when you drive. Is that the case at all?


Either way taking the caliper off, inspecting the pads and rotor, will probably tell you the culprit.

[alexxxa]

Originally Posted by 80stech

I would say it's a good bet that the caliper is starting to seize/drag. Did you notice anything when you spread the calipers to install the pads?? Are you sure there is no air in the hydraulic system? Caliper pins are good? A warped or bent rotor won't cause that problem. Wheel bearing would make lots of noise long before anything else.

Well, I didn't do it by myself. I'm more of an "electronic and electric" guy. My indie BMW specialized mechanic did that. And I believe the system was bled properly with the bleeding tool etc. The other three brake rotors are completely fine.
And if I remember correctly, the caliper pins also look fine. Just by looking and spreading the calipers, we did not notice anything odd. Everything looks as it should be.

My guess was also that it is less likely a rotor or wheel bearing. What about the bad pads? Is it possible that the right one is just thicker than it should be?

Originally Posted by Henn28

Agreed. Likely need a replacement caliper, or time to rebuild the one you have. Check the brake lines to the caliper too. I'm not sure if they degrade internally like other cars I've had, but they could be shedding crap into the caliper internals that is causing it to drag. One of my jeeps had the same issue your X is having several years ago and it took a new caliper and brake line.

Right, I forgot the brake lines! But if I remember correctly, from looking at them, they also seem okay. I think we're going to try with other calipers, as soon as my mechanic gets some free time. I wouldn't dare to do it by myself, because I may not properly bleed the system.
If the problem persists, then definitely the lines maybe...

Originally Posted by Bdc101

If it gets that hot I would expect the car pulls to the right when you drive. Is that the case at all?


Either way taking the caliper off, inspecting the pads and rotor, will probably tell you the culprit.

Well, the temperature is not that different between the left and right rotor. The left one gets on a hot day and a long ride up to 90 degrees Celsius (194F), while the right one goes up, tops to 160 (320F) - and that is after the caliper. By specs, if I googled correctly, these ATE Power rotors can get pretty hot, so this is not too problematic for them.. But it can get in the long run.

And no, it doesn't pull, because it is the rear rotor. And I noticed that it heats up only because I started to hear the noise coming from the rear right wheel, and I noticed a higher temperature in the right rear tire.

Anyhow, last time we took everything off, cleaned the caliper again, and tried to spread it... Everything seemed okay. But it isn't. So, I will try with the other set of calipers first.

And the handbrake pads? I believe they would heat up the entire disc a bit more evenly. It wouldn't be the hottest after the caliper?

[EODguy]

You didn't happen to grease your glide pins, did you?

Did you bed your brakes when you 1st got it back together?

When it's cool, do you feel any groves or waves on the rotor or did you turn the rotors when you did the brakes?

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[alexxxa]

I didn't do the work, the mechanic did it.
And if you mean did he bled the brakes, yes he did.

And when it's cool, no, the rotor seems pretty fine. However, I didn't send it to be checked.

What do you mean when you say if I turned the rotors? You mean if we tried to switch left and right?

[X5chemist]

Turning a rotor means machining it flat.

[EODguy]

Originally Posted by EODguy

You didn't happen to grease your glide pins, did you?

Did you bed your brakes when you 1st got it back together?

When it's cool, do you feel any groves or waves on the rotor or did you turn the rotors when you did the brakes?

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Greased glide pins pick up dirt and can drag or cause grease to get on the rotor making it sticky.

Bedding.....
https://brakeperformance.com/bedding-in-rotors.php

Turning a rotor is described above and gives you a new surface for the pads, plus it will show if it's true or too thin to use without warping.

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[mtthmpsn]

Originally Posted by alexxxa

Anyhow, last time we took everything off, cleaned the caliper again, and tried to spread it... Everything seemed okay. But it isn't. So, I will try with the other set of calipers first.

And the handbrake pads? I believe they would heat up the entire disc a bit more evenly. It wouldn't be the hottest after the caliper?

Late response, but curious if new caliper fixed the issue? My first thought was the handbrake pads - they're a little tough to set correctly (too tight and wheel won't spin freely when disengaged - too loose and handbrake won't hold car when engaged). But if both wheels were spinning freely when lifted, not likely the issue.