B5 S4 Rattling brakes + noise when braking

[Ryes7]

Hi Team,

Hope everyone is having a nice Friday. Pardon me if this is a dumb question but I’m struggling a bit with some brake noise. It’s a rattling noise coming from my driver front caliper and only occurs when I’m going over bumps or on washboard-like snow AND when I first press the brake there is a bit of a clunk. I am not a mechanic or brake specialist(obviously).

I’m mostly looking for direction on if there’s bolts I should tighten(I have a torque wrench and read that caliper bolts should NOT be over tightened), or if I should suck it up and take it to my local shop. The caliper feels a teeny bit loose if I try to move it with the wheel off, but not crazy. I’d like to mention that the brakes feel 100% fine as well when operating them.

Attached is the photo of the bottom of the caliper, please ignore the fluid as I had loosened what I think is part of the ABS to get to the triple square bolt up top and realized it wasn’t right maneuver.

Thanks AZ

[Cybersombosis]

Is it me or are those pads way past the edge of the rotor? I’d check to see if the pad has separated from the backing plate or if the pad isn’t seated correctly on the caliper. When I was rebuilding mine when I first picked up my S4, two of the pads had separated from the backing plate and were just floating when I separated the calliper from carrier. If you are handy, I’d remove the calliper and remove the pads to inspect them. Otherwise you are just guessing.

[travis_w]

Any fluid out of the caliper is going to be brake fluid. I would tighten that back up asap. That could cause spongy brakes.

Rattle when your going over bumps could be a lot things. Does the noise go away when you apply the brakes. A clunk up front could also be your control arms.

Is your clip in on the back of the pads and do you have pad life left?

Don't take off the triple square bolts

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[Ryes7]

Is it me or are those pads way past the edge of the rotor? I’d check to see if the pad has separated from the backing plate or if the pad isn’t seated correctly on the caliper. When I was rebuilding mine when I first picked up my S4, two of the pads had separated from the backing plate and were just floating when I separated the calliper from carrier. If you are handy, I’d remove the calliper and remove the pads to inspect them. Otherwise you are just guessing.

I will remove the caliper and check this out today. Thanks for the reply. The rotor sort of “floats” a very tiny bit while I feel like the others are tight and more seated. I just don’t like messing with brakes without direction as they are the most important piece of safety equipment on a car. Appreciate the reply

[Ryes7]

Any fluid out of the caliper is going to be brake fluid. I would tighten that back up asap. That could cause spongy brakes.

Rattle when your going over bumps could be a lot things. Does the noise go away when you apply the brakes. A clunk up front could also be your control arms.

Is your clip in on the back of the pads and do you have pad life left?

Don't take off the triple square bolts

Sent from my SM-S928U using Audizine Forum mobile app

As soon as a teeny bit of fluid came out of the top nipple I tightened it back up right away. Noise does in fact go away when I apply the brakes. It’s as if there is a slight gap between the pad and rotor. The clunk happens only happens precisely the moment when I first press the brakes. I will check the clip on the back of the pads. Yes, they appear to have a nice amount of life left. I’ll be sure to not touch the triple squares. Thanks for the reply

[2006b7a4]

When i had stock brakes the pad separated from the backing plate and it caused a rattle.


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[Calif_Kid]

If you work on the brakes or have them worked on, then it would be good to check the caliper slide pins (that are on the right side of your above image) to make sure that they are properly lubed and that the rubber bushing they fit into isn't too worn, plus there should be a cap covering the inside of the rubber boot. The slide pins and boots aren't expensive if you need to replace them.

On my car (2001 A6 2.7T 6-speed with the HP-2 front brakes), I had to remove the front rotors to remove the slide pins, and I used some 3M silicone paste to lube the slide pins.

- Jim

[Ryes7]

When i had stock brakes the pad separated from the backing plate and it caused a rattle.


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This feels a lot like what is happening. I made a video of what the brake looks like, pads and such. It just all looks normal-ish to me. Ran outta time so I threw the wheel back on.

https://youtube.com/shorts/11jhlzKpJ...gWa9gUc_3Xm7RA

[Ryes7]

If you work on the brakes or have them worked on, then it would be good to check the caliper slide pins (that are on the right side of your above image) to make sure that they are properly lubed and that the rubber bushing they fit into isn't too worn, plus there should be a cap covering the inside of the rubber boot. The slide pins and boots aren't expensive if you need to replace them.

On my car (2001 A6 2.7T 6-speed with the HP-2 front brakes), I had to remove the front rotors to remove the slide pins, and I used some 3M silicone paste to lube the slide pins.

- Jim

I haven’t really worked on them beyond tightening the a couple bolts. I will check this out. I made a video of the brake and it looks normal, it’s just ever so slightly loose. I’m a little hesitant to pull them apart too much because it feels as if they are functioning well, it’s more of a nuisance noise kinda thing at this point.

https://youtube.com/shorts/11jhlzKpJ...gWa9gUc_3Xm7RA