Disc Brake Rub after new pads/rotors - PeachParts Mercedes-Benz Forum

suncat · #1 12-25-2007, 06:03 PM

Just last week I installed new front brake pads and rotors on my 95 C280. The pads on the front left are rubbing ever so slightly - not really causing any drag, but I notice a slight recurring noise when driving it now. Is this normal? Do I need to pull it apart and re-set things? I did spray the back of the pads with a quieting "goo" by Permatex.

Would love to hear about whether I need to adjust anything here, or just let them wear in. I am ready to do the rears as well, so anything I can learn about this would be helpful on the next time around.

Thanks, and happy holidays to all!

Ferdman · #2 12-26-2007, 08:16 AM

It's possible the calipers are not releasing properly, but more likely the pads are wearing in. Not familiar with the design of the brake pads on your 1995 C280. There is a reusable stainless steel shim for the front brake pads on our 1991, 1992 and 1995 E-Class automobiles. Anti-squeal paste goes between the stainless steel shim and the back of the brake pad.

suncat · #3 12-26-2007, 08:39 AM

Thanks for the response, but no shim on these ones. After reading the multitudes of posts about brakes on this forum, I was surprised to find that the fronts didn't even have the "pin type" pad replacement. Had to pull off the caliper to replace the pads (like every other non-MB disc brake job I have ever done). The rear brakes have the pins, tho'.

Any other thoughts out there?

yal · #4 12-26-2007, 11:16 AM

Yes, did you grease the caliper slide bolts?
The outer side of the caliper slides towards the inner side when you hit the brakes. It glides on two shafts that need to be greased.

ILUVMILS · #5 12-26-2007, 12:08 PM

Maybe the noise is the backing plate rubbing on the inner side of the rotor. It's easy to hit the plate when removing/installing the wheel. You don't have to hit it hard either.

david s poole · #6 12-26-2007, 12:16 PM

possibly your rotors have a wear lip on them and one or both pads are dragging on that lip until they wear down.

suncat · #7 12-26-2007, 10:37 PM

I did not grease the slide bolts - that sounds like a good thing to do. Any particular grease? I typically use a Valvoline semi-synthetic grease which has an excellent temparature range. Any problems with that?

The old rotors had a terrible lip on them, so I put on brand new rotors. There don't appear to be any "high" spots that would rub, as would be expected on new rotors...

I'll grease the slide bolts... I presume I simply pull back the rubber boot that goes over them and wipe on some grease?

I will also check out the backing plate when I take off the wheel to do the side bolts.

Any other thoughts on whether this is a common issue that just requires a little wear-in? Have others experienced this matter before?

Thanks for all of the great replies so far, BTW.

suncat · #8 12-26-2007, 11:13 PM

OK - half an hour later, here's the update:

Backing plate is OK - no rubbing there.

I greased the slide bolts. They were gummy, but still slid pretty easily. I would say I improved the sliding ease, but not the range.

Tomorrow I'll drive it and see if there is any improvement, but the pads are still rubbing on the rotor when I reinstall the wheel and turn it by hand. I hope this is simply a wear-in issue. There aren't any post-install adjustments I am supposed to be making are there?

Xsbank · #9 12-27-2007, 01:35 AM

There is supposed to be a small amount of run-out in the rotors that is intended to push the caliper pistons back in their bores when you release the brake pressure by removing your foot. If the run-out is inadequate or the pistons are sticking in the bores (corrosion or pitting can occur if the fluid is not changed at the required intervals) then the calipers need attention. I'd guess that the pins that you greased are not allowing smooth motion from the calipers and you might need to remove them to properly clean and re-grease the pins.

Are you using the same pads you used before? If you are using aggressive metallic pads that are not bedded in yet, you might get some scraping noises, and the rears are slow to bed in.

Could it be your emergency brake pads? Have you done that thing they say in the manual, 30 kph, pull the brake handle so it won't lock and push the pedal down. Cleans all the gunk out....

suncat · #10 12-27-2007, 08:30 AM

In response to xsbank:

It's the left front from which I was getting the noise, so it wasn't the e-brake. I have yet to work on the rears (hoping to get the front straightened out here first).

I did remove the slide bolts to clean and regrease.

The pads are new and are the OE compound, which I beleive is semi-metallic.

As I mentioned last night, I will drive it today and see if things are better & report back.

Xsbank · #11 12-27-2007, 12:42 PM

Sorry - I re-read your reply and I see that it was the fronts. My bad.

suncat · #12 12-27-2007, 02:42 PM

Well, thanks again to all who posted. I don't know if it was the act of disassembling the brake to grease the slide bolts or if the pads were maybe not seated properly when I assembled it the first time around, but so far, the brakes have been quieter (i.e. I can't hear them making nose while driving down the road). As I mentioned in my last post, there is still some minor rubbing that I would expect to disapate as the pads wear in. I'll see how they perform after driving a few days and see if the minor rubbing goes away completely.

Thanks again for all the advice. Now it's time to plan for doing the rears.