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Discussion Starter #1
Noticed a grinding noise that suddenly started to get loud. Then it went away. Then it came back.

I noticed that the noise isn't there if the car is driven on a highway, then as soon as brakes are applied and then released it makes the grinding noise for a few minutes until it goes away.

Basically drove 100 miles on highway, no noise. Then last mile I had to brake, and kept making a grinding noise entire way. Its coming from front right wheel area.

Took it for a short drive next day and the noise was gone. Any idea what it can be? Stuck Brake caliper?
 

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Definitely get under there with a flashlight and look at the surface of the disc rotor. Particularly the inside surface you cannot see through the wheels. If you see grooves and a chewed up look then you need someone with skills to immediately confirm your brakes are not a danger to you or others. Don't go driving it on the highway like that again until you've checked that right front rotor. Compare it to the left front as well if you don't know brakes. Start there but make that a priority.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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I'm not there. However what you describe could very well be a sticky front brake caliper.
 

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If you hear a grinding sound after you step on the brake pedal, then it could mean that your brake pads are worn out. When your brake pads go bad, you need to get them replaced ASAP. If you're hearing a grinding noise when braking but the pads are fine, keep reading.
 

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When inspecting the brakes/brake rotors.
Lest you forget to remove the wheel/tire and completely inspect the inside of the brake rotor.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Hence the suggestion of a sticking caliper
 

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2016 340i xD 6-spd
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It is possible that you could disassemble, clean, grease and reassemble and be free of your issue.

But, it does sound like you're sticking...and if it's the piston sticking, you should replace the caliper.

Next time you're driving and hear the sound...pull over without using your brakes and measure your rotors' temps.

If one is significantly hotter...you've found your corner with the problem for certain.

Caliper is not hard to do once the brake is apart anyway...and your other side will probably not be far behind...so be prepared.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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What I gave is a suggestion.
Before ANY work is performed; Verify what's wrong.

The 3 "C's" Complaint, Cause, Correction.
Focus on the later two.
 

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What I gave is a suggestion.
Before ANY work is performed; Verify what's wrong.

The 3 "C's" Complaint, Cause, Correction.
Focus on the later two.
Years ago here someone complained of a squeaking brake, discovered the cause was the pads, and wanted to know if removing the pads would correct the problem.

I miss him. :)
 

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Noticed a grinding noise that suddenly started to get loud. Then it went away. Then it came back.

I noticed that the noise isn't there if the car is driven on a highway, then as soon as brakes are applied and then released it makes the grinding noise for a few minutes until it goes away.

Basically drove 100 miles on highway, no noise. Then last mile I had to brake, and kept making a grinding noise entire way. Its coming from front right wheel area.

Took it for a short drive next day and the noise was gone. Any idea what it can be? Stuck Brake caliper?
Stuck or loose caliper / pad or missing spring.
 

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Discussion Starter #13
Alright I ended up having to buy 2 different brake calipers because the parts store had no idea which one was correct. According to realoem my required part number is 34116758114. I have a Canadian built 320i and they weren't sure if it was the same part as a 325i or not.

I looked at the caliper and it has some numbers written on it however it doesn't have the entire part number. Anyone know why they didn't stamp the part number anywhere on the caliper? Just has some numbers written on it which looks like built dates and that's it. I'll post photos later when I get home.
 

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I don't know about the rest of you, but I love threads like this.

OP: My brakes make a grinding sound and I have not looked at them at all.
FORUM: Look at your brakes
OP: OK, rather than bending down with a flashlight, I just had the entire brake system done at the shop for $2200 including pads, calipers, rotors, wheel bearings. Thanks for your input.

Cough.....

(sorry, feeling ornery today - I was going to work on the Supra all evening last night and accomplish a wrenching milestone before a trip Friday but did not. Perhaps tonight my orneriness will flow into installing the cams and being completely DONE with the heads.)
 

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Discussion Starter #15
I did look at the brakes and couldn't find anything odd. The pads still had some life in them left. Nothing was rubbing such as a heatshield.
 

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The brakes are the only system I have not replaced on my 46, so I don’t know yet if they still rotate between ATE and GIRLING like they did on the e30’s. My 30 has ATE rears and Girling fronts. (Don’t quote me on that, been a while since I did all that stuff). Heck, I have a complete rotor/pad set for my 39 ready to be installed and I don’t know if they are ATE or not.

All the same, is this why the correct calipers were unknown? At any rate, last 7 of the VIN at real.OEM would have solved it. Brake components are relatively cheap all things considered, if you have a problem just replace everything if you can do it yourself.
 

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Steel,

OK, when were you going to post that you looked and all was normal? I guess after you bought apparently one caliper, so now is a good time for you to learn it's unwise to replace a single caliper - they should be replaced in pairs (especially fronts).

And also a good time to learn if you'd reported that "looks normal" it may have been resolved with a dab of grease on your caliper slider pins for $1.29 and 10 minutes of work. I don't mean to be grumpy, but it's often useful to keep informing someone you're looking for quality advice on, where you seem to have made a huge leap into spending money instead. I hope you don't snap a rusty brake line fitting replacing the caliper in a hurry, and I hope your car doesn't start pulling to one side after you deal with the now much bigger job of replacing a caliper but only one side. And I hope you are also replacing the pads. On both sides. And I'm hoping you know how to properly bed in those new pads. Which I hope you know you SHOULDN'T do if you've put pads only on one side. If you're getting the impression you have half the knowledge to do this repair improperly, so do I. Not meant to be confrontational, just sharing what happens with threads sometimes. And yes, I got the cams back in my Supra head and it's ready to bolt back on. So I'm not actually grumpy!! Woohoo!!!
 

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Discussion Starter #18
I bought everything for both front sides except the front left caliper because it was out of stock. Pads, brake hose, etc. I got flare wrenches and everything for the brake hose fittings.

I'll do what you suggested and lube the caliper guides and maybe it'll get lucky and the noise will go away. Can you use brake grease on those or do I need to buy the silicone paste due to the rubber? The 50skid youtube video said not to use brake grease.

However I am skeptical this will fit this issue, most likely will need to replace entire caliper so decided to buy it just in case since I need to take everything apart. I can always return for full refund as long as its not installed.
 

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Don't overlook the dust shield. When it gets rusty and starts to break up/distort, it can makes all kind of scraping, grinding noises.
 

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Hmm, just confirmed you are correct - no lube on the guide pins. So, just pull them, wipe the pins off, blow any dust out of the place they slide and reassemble. And of course while you're doing that, confirm the bolts holding the caliper on are tight, etc. If you find corrosion in there due to rotted rubber boots, you can get a kit with new pins and boots for perhaps $10. Next time it happens, watch your dash to see if your stability control is activating as that could also be the issue. If the rotors are not obviously stressed, neither are the pads, then keep looking for something simple or odd.
 
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