"clunk" when brakes are applied

Seems to be coming from the back rear wheel. I can't make the sound by lifting the wheel off the ground and yanking on it. Could pads without a raddle brace make a clunking sound? It's not metallic sounding. Nothing like a worn drive shaft
I sense absolutely no performance difference, vibration, or know that there is a problem except by what my ears hear.

I recently replaced diff, axes, shocks, and springs, though it drove for a few weeks before making this sound.

Thought?

My strategy at this point is to take the wheel and calipers off, look at things, put it back together and cross my finger

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

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Bob in Everett
Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

I'll do that. To clarify, there is no sound under accelerating, or on release of the brake. The clunk occurss at the initial moment of deceleration. And most of the time, repeatedly tapping the brake once every second will cause a clunk for each time the brakes is pressed. Also, the amount of pressure makes no difference, as long as there is deceleration. However, accelerating down a hill in 2nd and letting off the gas and engine braking doesn't cause a clunk.

Still, tightening everythingto spec should happen while I'm looking at things

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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Earendil

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Bob in Everett
Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

I'll do that. To clarify, there is no sound under accelerating, or on release of the brake. The clunk occurss at the initial moment of deceleration. And most of the time, repeatedly tapping the brake once every second will cause a clunk for each time the brakes is pressed. Also, the amount of pressure makes no difference, as long as there is deceleration. However, accelerating down a hill in 2nd and letting off the gas and engine braking doesn't cause a clunk.

Still, tightening everythingto spec should happen while I'm looking at things

Right rear shock mount

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Archeo-peteriX

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Earendil

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Bob in Everett
Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

I'll do that. To clarify, there is no sound under accelerating, or on release of the brake. The clunk occurss at the initial moment of deceleration. And most of the time, repeatedly tapping the brake once every second will cause a clunk for each time the brakes is pressed. Also, the amount of pressure makes no difference, as long as there is deceleration. However, accelerating down a hill in 2nd and letting off the gas and engine braking doesn't cause a clunk.

Still, tightening everythingto spec should happen while I'm looking at things

Right rear shock mount

Maybe, but they usually make noise over bumps. Could be loose pads in the caliper housing or something loose back there. If it just clunks on braking, that would seem logical (doesn't always have to work that way though). You might see if any of the hand brake parts have come adrift too.

Rick

Didn't Cab have a problem like that once?

I don't remember if he ever managed to track it down and fix it though...

Ah, hell... I haven't darkened the door of the Tech Forum in forever...

I had some clunking/rattling noises coming from the rear of the E30 that I never truly diagnosed to any real satisfaction. It wasn't necessarily only under braking, though. It would happen sometimes just when one side of the car (I think it was the right side) was unloaded over rough/frost-heaved roads. Never solved it, though. I also replaced just about everything in the car rear of the driveshaft.

However, my E30 hasn't been on the road for almost 4.5 yrs, so any and all recollections I have are to be understood to be highly suspect.

Cab
1990 325i(s)
2004 325XiT

Thanks for dusting off the tech forum link

As soon as I wake up and don't find new snow on my car and the ground, I find a good spot for a jack and see what I can see. Until then, my baby is handling better than she ever has on the snow and ice!

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1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

Just for giggles, is your battery secured? Anything rolling around in the trunk? Spare secured?

alan

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alanrw
Just for giggles, is your battery secured? Anything rolling around in the trunk? Spare secured?

alan

As I remember, we, Cab and everybody went through his whole car, I think I decided it was the LSD clunking away back there; they do tend to get sloppy with age and hard use. I think that style rear is prone to noise in general, even tight ones. That has been my experience anyway

Rick

yeah, a clunk can be u-joints or the diff loosening up.

alan

The only other thing I thought of, but I'm sure you've checked this out, is to check all the caliper mounting bolts. I have had bolts go loose before and then the whole caliper shifts slightly when applying the brakes, resulting in that type of sound. And if you've done anything in the front of the car recently, I'd check the bolts on the front calipers as well. Sounds have a funny way of moving around and can be hard to pin down from the driver's seat while in motion... Just a sanity check. You definitely don't want to be cruising around with loose caliper bolts.

The rear shock mounts are also something to consider, but that should also make a noise when turning corners, and not ONLY when braking...

Cab
1990 325i(s)
2004 325XiT

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Cab Treadway
The only other thing I thought of, but I'm sure you've checked this out, is to check all the caliper mounting bolts. I have had bolts go loose before and then the whole caliper shifts slightly when applying the brakes, resulting in that type of sound. And if you've done anything in the front of the car recently, I'd check the bolts on the front calipers as well. Sounds have a funny way of moving around and can be hard to pin down from the driver's seat while in motion... Just a sanity check. You definitely don't want to be cruising around with loose caliper bolts.

+1

If they haven't got loctite they will work themselves loose. I've had both front wheels get loose brake caliper bolts about a year apart. Starts with a "cluck", evolves to a grinding feeling (feels similar to a worn-out wheel bearing).

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rkj

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Archeo-peteriX

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Earendil

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Bob in Everett
Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

I'll do that. To clarify, there is no sound under accelerating, or on release of the brake. The clunk occurs at the initial moment of deceleration. And most of the time, repeatedly tapping the brake once every second will cause a clunk for each time the brakes is pressed. Also, the amount of pressure makes no difference, as long as there is deceleration. However, accelerating down a hill in 2nd and letting off the gas and engine braking doesn't cause a clunk.

Still, tightening everything to spec should happen while I'm looking at things

Right rear shock mount

Maybe, but they usually make noise over bumps. Could be loose pads in the caliper housing or something loose back there. If it just clunks on braking, that would seem logical (doesn't always have to work that way though). You might see if any of the hand brake parts have come adrift too.

Rick

Dear Everyone,

It must be the Season of the Clunk. I too have this problem now. About 2 months ago, my rear shocks and mounts were changed. Two weeks ago all the brakes (rotors and calipers) were replaced. After about a week with the new brakes, the clunk began. I do not think that I ever heard the cluck before the new brakes. It occurs randomly usually only once or twice per trip and only when I release the brake pedal. At first I thought it was a floor jack* knocking around in the trunk. Removing the jack did not improve the situation. (* I don't think that I told you that I found a floor jack in the middle of an intersection. As I drove past its blocky form, I decided that it needed to be rescued. I pulled to the curb in front of a fire hydrant and parked. I watched for both Police and former owners. When neither appeared in a few minutes, I simply walked across the intersection and picked it up - with both hands. It is quite heavy. How do I know if it is safe to use? It does not appear to be leaking, and seems to be in pretty good condition. There is a little surface rust. I could send a picture if you like. Back to the main story,...)

I passed the mechanic's shop last night at 7pm and noticed the lights on. (I did mention to the mech that the risk of leaving the lights on in the evening was that clients would stop in for unexpected visits. He said that he needed the light to sweep. I offered the idea of a miner's headlamp.) We drove forward about 15 ft and then backward about 15 ft a few times. He was able to provoke a few clunks. He thinks that the calipers may be shifting. I'll return Beemie to the shop on Monday for another inspection.

How are they shifting - clockwise/counterclockwise? What are they hitting? Why didn't they make the clunk before?

Fa la la, Kelly

Hi all
I would go with the diff clunking away back there, as has been said, they do it with age, mine does it as well, but it does not worry me, those things are built like Sherman tanks inside, they will never break and leave you on the side of the road, so I just drive it, mine is a 4.11:1 ratio and those are pretty hard to come by here, as the guys scoop them up pretty quick when they do come up for sale.

Kelly, I can't say yours is the same, as the diff would clunk under deceleration not only when applying brakes, maybe loose caliper???

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.

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Kelly
He thinks that the calipers may be shifting. I'll return Beemie to the shop on Monday for another inspection.

How are they shifting - clockwise/counterclockwise? What are they hitting? Why didn't they make the clunk before?

Fa la la, Kelly

My money is also on it being the calipers (I reckon the bolts weren't tightened properly and have worked themselves loose over the past week). Mine was just the caliper rattling around in its housing (parts 2 and 3 here), although if left too long the bolt could fall out completely and then the caliper will start dragging on the rotor (which will make very painful noises so don't worry the noises you're hearing now are nothing serious).

If you pull the wheel off you can find the problem by wiggling the caliper (your hands will get covered in brake dust). Then just tighten the bolts, but use loctite because otherwise it will work itself loose again.

Simon

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Kelly

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rkj

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Archeo-peteriX

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Earendil

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Bob in Everett
Might want to check for loose bolts on all the suspension that you have worked on. Sounds like the suspension moves to one position under acceleration and then the opposite torque applied by the brakes moves it the opposite position. Just put a wrench on all the bolts and check the torque.

Bob in Everett

I'll do that. To clarify, there is no sound under accelerating, or on release of the brake. The clunk occurs at the initial moment of deceleration. And most of the time, repeatedly tapping the brake once every second will cause a clunk for each time the brakes is pressed. Also, the amount of pressure makes no difference, as long as there is deceleration. However, accelerating down a hill in 2nd and letting off the gas and engine braking doesn't cause a clunk.

Still, tightening everything to spec should happen while I'm looking at things

Right rear shock mount

Maybe, but they usually make noise over bumps. Could be loose pads in the caliper housing or something loose back there. If it just clunks on braking, that would seem logical (doesn't always have to work that way though). You might see if any of the hand brake parts have come adrift too.

Rick

Dear Everyone,

It must be the Season of the Clunk. I too have this problem now. About 2 months ago, my rear shocks and mounts were changed. Two weeks ago all the brakes (rotors and calipers) were replaced. After about a week with the new brakes, the clunk began. I do not think that I ever heard the cluck before the new brakes. It occurs randomly usually only once or twice per trip and only when I release the brake pedal. At first I thought it was a floor jack* knocking around in the trunk. Removing the jack did not improve the situation. (* I don't think that I told you that I found a floor jack in the middle of an intersection. As I drove past its blocky form, I decided that it needed to be rescued. I pulled to the curb in front of a fire hydrant and parked. I watched for both Police and former owners. When neither appeared in a few minutes, I simply walked across the intersection and picked it up - with both hands. It is quite heavy. How do I know if it is safe to use? It does not appear to be leaking, and seems to be in pretty good condition. There is a little surface rust. I could send a picture if you like. Back to the main story,...)

I passed the mechanic's shop last night at 7pm and noticed the lights on. (I did mention to the mech that the risk of leaving the lights on in the evening was that clients would stop in for unexpected visits. He said that he needed the light to sweep. I offered the idea of a miner's headlamp.) We drove forward about 15 ft and then backward about 15 ft a few times. He was able to provoke a few clunks. He thinks that the calipers may be shifting. I'll return Beemie to the shop on Monday for another inspection.

How are they shifting - clockwise/counterclockwise? What are they hitting? Why didn't they make the clunk before?

Fa la la, Kelly

Hey Kelly

The best test for a floor jack (lucky you) is just to jack up the car and leave it overnight (or as long as you can) and she if it holds. If it does you're golden, if not a kit make fix it. What kind is it?

Your clunking in the rear end could be loose pads in the caliper housing; a lot of guys use rebuilt calipers and they can be rusty before the rebuild and looose after they're rebuilt. You're right to go back and let your guys sort it out. If they are in fact new they might have used aftermarket pads, and those can be a bad fit (sloppy) too.

Brakes can be a tricky one, most of the time everything works out fine but then there are other times....

Good luck, and keep us posted- Happy everything sweetie