When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I ran out of time before a track day and had a local shop replace my brake pads. I'm now hearing a noise that sounds like that rear pads are moving when I apply the brakes after changing direction (forward/reverse). There's a little 'pop' from the rear when I first touch the brakes. I don't hear it if I reapply the brakes while moving in the same direction.
Another description: if I'm driving forward and apply the brakes and come to a full stop, there's no noise. If I put it in reverse and start backing up, the first time I apply the brakes there's a 'pop'. I can continue with repeated stopping, backing and braking and there is no more noise. If I then put it in drive and begin moving forward, the first time I apply the brakes, I hear the 'pop' again.
I've not removed the pads on this car before and I'm not sure how they are secured. Is it possible that the shop left off something that keeps the pads from moving in the caliper?
2012 P31 C63 Coupe Trackrat, 2019 GLE63S Coupe Beast
Take the wheel off and look at the back side of the caliper. There should be a metal spring plate held in there by the upper and lower pins, which keep the pads in place with tension. Sometimes these can click if not seated properly. Also could have been installed in reverse. With that in place correctly, the pads should not move.
W204 C63 Coupe, W166 ML350 BlueTEC, 928GT, C5 Z06 & IS300 race cars, EQE 4Matic+ on order
Originally Posted by BLKROKT
Take the wheel off and look at the back side of the caliper. There should be a metal spring plate held in there by the upper and lower pins, which keep the pads in place with tension. Sometimes these can click if not seated properly. Also could have been installed in reverse. With that in place correctly, the pads should not move.
+1. Accidentally reversed on a friend's car when swappign the pads allowing the pad to move. No issues once we put it in the proper way and it reseated.
I checked the spring and it looks like it's in right:
A local Indy shop that specializes in Mercedes did the pad install for me, and kindly gave me the OEM pads. I see some key differences. The back of the old pad has what looks a layer of insulation material and a separate metal backing plate. There are also a couple strange-looking ears on the top of the pad. The shop didn't move any of this to the new pads. What's the purpose of these things and should they have been moved onto the new pads?
The backing material on the old pads wraps around the sides, making them a fraction of an inch longer than the new pads. I installed one of the old ones and it is tight enough that it doesn't move. The gap at the ends of the new pad DOES allow a small amount of movement and it takes very little effort to make it move. That HAS to be the reason for the 'pop' noise I'm hearing from the rear brakes.
I also have RacingBrake rear pads (in my case the XT960 compound). The backplate is the same, the anti squeal weights that the OEM pad has, are also absent and I also do not have any anti-squeal shim between pad and piston. In short, my pads look like yours.
No movement or noise discernible in my case.
If you hear a clunking noise when going from forward to reverse, it is much more likely to come from a joint in the half-axle, or the diff, in my humble opinion.
I also have RacingBrake rear pads (in my case the XT960 compound). The backplate is the same, the anti squeal weights that the OEM pad has, are also absent and I also do not have any anti-squeal shim between pad and piston. In short, my pads look like yours.
No movement or noise discernible in my case.
If you hear a clunking noise when going from forward to reverse, it is much more likely to come from a joint in the half-axle, or the diff, in my humble opinion.
Thanks - anti-squeal weights? I would never have guessed.
The fact that your XT960 pads don't do this is interesting feedback.
The noise in mine is unquestionably coming from pad movement. It's not driveline - doesn't happen when shifting from fwd to reverse. It only happens when you first apply the brake after starting to move in a new direction. More importantly, even with the brake fully assembled and the spring in place, I can move the pads back and forth with a fingertip and hear the noise. When I put the OEM pad back in, it's tight enough that I can't make it move and can't make it make the same noise.
RB - do all of your pads for the C63 have exactly the same dimensions on the backing plate? Is the long dimension on your pad the same as the OEM backing plate, or is it the same as the OEM plate plus the backside attachments (which wrap around the side of the backing plate and add a couple mm to the long dimension)?
Yes, the thing with anti-squeal weights is my guess. Those weights reduce the resonance frequency of the pad, so I figure. I could not come up with any other plausible explanation.
Now that you made me think, maybe there is a bit of a clacking noise on my car too. I never attributed it to the brake pads, but it is possible. Frankly, It does not bother me. If it is the pads, it'll probably go away completely as more brake dust and a bit of rust accumulate.
On my wife's car (SLK55) I had the opposite problem: Pads rusted in and not moving freely any more. I'd rather have a bit of movement.
I am on my way to the track (VIR) today with that setup.....
The weather in Texas was beautiful today and I got to spend most of it at the track. This much fun should really not be legal. Hope you guys have a blast at VIR!
Just a quick props to the team at Racing Brake. They took the initiative to reach out and help. I'm really impressed. I wish all of the vendors I deal with cared about their customers like these guys do. If you're interested in improving the way your ride stops, Racing Brake is the only place to go.
Too early to tell. First step is to try putting the metal backing plate onto the RB pads, and the folks at RB were kind enough to offer a set of spare backing plates to test with. I'll update after I've had a chance to test.
At this point I'm the only one who has run into this, so it may just be something peculiar about my car. I think you guys are running a different caliper (mine are the standard stock C63 version), so it may not be an issue for you. Wobble, just to confirm, you may want to check yours for movement while your wheels are off. In any case, it is more in the 'occasional minor annoyance' than the 'big problem' category, so I'm not sweating it.
10-14-2015, 08:46 AM
