clunking noise from brakes?

Post by **Clemens** » 08 May 2019, 12:52

So I am hunting a clunking noise which is caused by applying the brakes with pressure (not just tapping them). If i brake hard, there is a clunk from the left or the right front. then, if I engage, the clunk is back. Just a short clunk. Like the sound of a worn out sway bar link. I had my indie check all the suspension parts and everything during safety inspection last week, and he said the only thing he could think of are the brake pads making the noise, especially since the inner ones have some play within the guides (the oter ones don´t). All OEM Volvo parts, all in good condition. All joints, driveshafts, bearings, strutmounts, ... look okay.

The only other thing we thought about was the tranny/differential, but the tranny is super smooth, the only thing is that you can hear some play in the differential if the car is on the lift. Then, if you spin teh tires by hand and change the direction of rotation a little clunk can be heard. (my indie said this is probably normal as there should be some play in the diff assembly, sounds reasonable). Whenever I flushed the tranny there was barely any metal debris on the magnet.

It is kinda annoying, but also kinda makes me worry what it could be.

tardcart · Post by **tardcart** » 10 May 2019, 04:40

a clunk wouldn't be the pad slop, that would be a small tink. The suspension is twisting forward as you brake, thats attached to the sub frame and strut. maby the subframe bushings or bolts are loose? but I think its coming from slowing the rotational mass of the drive line.
and some problem there. what happens if you accelerate and let off in low gear with out braking, does it do it too?

Post by **850 LPT** » 10 May 2019, 06:30

I have a clunk happening just like what you are describing with my 850. I think your mechanic is right on when he is saying that it comes from the front brake pads having too much play.

Mine started happening right after I replaced the brake pads. Old ones no clunk- new ones clunk, so I know that this is the problem. I changed to Akebono pads, but I wouldn't not necessarily blame them. Have used many sets before with no problem.

All parts involved in the caliper setup have certain tolerances. And I think every now and then it can happen that the gaps are just a little on the larger side, and then you get a clunk.

If it bothers you enough, replace the pads and see if that improves it.

Good luck, Dirk

Klausc · Post by **Klausc** » 10 May 2019, 14:11

Using very light pressure on the brake pedal should also create the 'clunk', not just hard braking. I would check the engine mounts for wear/play, especially the upper mount.

Post by **DeadEric** » 10 May 2019, 20:19

Pads loose in the brackets is more of a click than a clunk...

I'm wondering, under what conditions it occurs, more specific than hard braking. Can you hear it if you're stopped, let off the breaks, then slam them after 10 feet? Is it only over a specific speed? Any odd wobbleing at over 50mph hard breaking?

Post by **Clemens** » 11 May 2019, 00:14

@tardcart: if I let off the throttle or get on it without applying the brakes prior to that nothing happens.

The subframe bushings are worn, they could be the source

@850LPT: maybe it is excessive tolerance in the pads.

@klausc: i will check the motor mounts. I replaced all of them last year with OE. Maybe a bolt came loose.

@deaderic: no wobbling over certain speeds. i will try to find out if there is a minimum speed that I have to exceed to cause the clunk.

I still wonder if that play and noise I heard when spinning the wheels back and forth on the lift was normal. But overall the tranny and drivetrain are super smooth, hard to imagine this is the culprit.

Post by **Clemens** » 15 May 2019, 13:56

Okay, breaking into this again ...

I drove around town for a while, on differnet days. The noise seems to be linked to braking. If cruising downhill, slightly tapping rhe brake pedal will make a clicking noise, letting off the brake pedal rifht afterwards while still in motion will again make a clicking noise. If I stay on the brakes longer or hit the pedal harder it might make a clunk as soon as I hit the gas pedal. But not always. I double checked the motor mounts, all bolts are tight, the motor barely moves if i try to move it by hand.
I wonder if I hear two different things: clicking brake pads and then maybe worn subframe bushings if i come to a halt with increased brake force.

I still doubt the diff is the culprit. Can anyone confirm that you can hear the gears click when changing the tire spinning direction with the wheels off the ground?

One more thing: I am not sure if I still have the original front calipers on the car. I know I did the rears, but with 3 850ies I kinda lost track of a few things that I did. Maybe I will tear the front brakes apart, get new pads and check the condition of the calipers.

Post by **abscate** » 15 May 2019, 14:24

Are your caliper springs in good shape and in position correctly? The caliper will clunk if they are missing.

Post by **Clemens** » 15 May 2019, 14:34

They are in place, and I replaced them with blue box units last time doing pads, I believe.

Post by **abscate** » 15 May 2019, 15:07

Clemens - can you still get 3546381 over there, OEM brake springs?

I think they are NLA over here.