Funny Brakes... Is it this wear line any indication? - Page 2 - PeachParts Mercedes-Benz Forum

t walgamuth · #16 06-26-2014, 09:02 PM

Quote:

Originally Posted by 97 SL320

According to the thread below, the rust will just wipe off after a few days of normal driving. ( It won't. ) Rust has reduced the proper rotor area to 25%.

Rust Spots Rear Rotors: Necessarily Indicative of a Problem?

I've seen worse, in the current thread. Top pic in post 13 shows a growing ring of rust that has become burnished by the pads. While not a major disaster to drive on, I'd get some use out of the pads / rotors and change both at the next service. Be sure to repack wheel bearings too.

If they are rear brakes, you really cannot pack the bearings on a Mercedes.

azitizz · #17 06-26-2014, 09:58 PM

Ya, and what ticks me off a little is that the callipers, pads and rotors are all less than a year old.

Its an almost daily driver car. Its our only car. We dont go out everyday of course... I walk 3 minutes to work.

I try getting a better look tomorrow if I get a chance and post results.

Thanks for all the links and info. Its an interesting dialoge. Lots of different opinions, which is good...

tjts1 · #18 06-26-2014, 10:01 PM

If the calipers are relatively new, you might have a bad rebuild which would explain the quick failure.

EDBSO · #19 06-26-2014, 11:13 PM

Quote:

Originally Posted by vstech

it looks like he has pads that are MUCH smaller than the face of the rotor. I bet his pads are incorrect for the car.

OP: please pull the wheel, and the caliper and post pics of it all...

+1 wrong pads and or rotors

vstech · #20 06-27-2014, 01:19 PM

Quote:

Originally Posted by toomany MBZ

Okay, at least one of the attachments has been enlarged.

if you look at your original pic, and compare it to the edited one below, you will notice the red area of the OP's rotor has no wear from the pads... your pads are wearing correctly, and there is a small ridge on the outer edge of the rotor.

97 SL320 · #21 06-27-2014, 04:01 PM

The calipers are fine and the pads were the proper height. Look carefully at the outer edge rotor rust, it has been burnished by the pad. The pic above shows how the rust starts growing _under_ and _into _ the swept surface.

Pull the wheel, pull the pad and you will see a groove at top / bottom of pad.

Given the rotors are full thickness have them resurfaced then sand the pads flat with 40 grit paper. Chip the rust off the rotors before refinishing so you don't get cutter chatter. Bed the brakes in like they were new.

toomany MBZ · #22 06-28-2014, 06:45 AM

Quote:

Originally Posted by vstech

if you look at your original pic, and compare it to the edited one below, you will notice the red area of the OP's rotor has no wear from the pads... your pads are wearing correctly, and there is a small ridge on the outer edge of the rotor.

Thanks.

engatwork · #23 06-28-2014, 07:23 AM

If it is all new parts someone put the wrong pads in it.

eatont9999 · #24 06-28-2014, 05:14 PM

It looks like no contact is being made with outer 1/4 to 1/3 inch of the rotor. I know rear pads are smaller than front pads but is it even possible to install rear pads in the front? Perhaps something like that happened here?

I have a complete set of brake pads in the trunk of my second 300SD. I suppose I could I run out there and compare rear and front pads to see if the caliper pins would even line up. I tend to doubt it, though.

eatont9999 · #25 06-28-2014, 05:34 PM

I checked and there is no way that would make sense to install rear pads in the front. What brand of pads were used?

vstech · #26 06-28-2014, 06:00 PM

Until we get pics of the pads and rotors disassembled, I'm siding with 97-SL320

Quote:

Originally Posted by 97 SL320

The calipers are fine and the pads were the proper height. Look carefully at the outer edge rotor rust, it has been burnished by the pad. The pic above shows how the rust starts growing _under_ and _into _ the swept surface.

Pull the wheel, pull the pad and you will see a groove at top / bottom of pad.

Given the rotors are full thickness have them resurfaced then sand the pads flat with 40 grit paper. Chip the rust off the rotors before refinishing so you don't get cutter chatter. Bed the brakes in like they were new.

azitizz · #27 07-03-2014, 04:00 PM

So Got a chance for a closer look today. It looks like the brakes are making contact even on the rusted part.

Its as if the rust penetrated into that first layer. I chipped it off for now. Ill have to get them resurfaced.

The pads were fairly good quality ones, I would have to look up the brand name again but I remember wanting to get a bit better quality as my old ones wore quite fast.

The pads don't have a noticeable indent where the rst line is but I didnt actually take them out.

The shot of the callipers and brake pads is of the left side, which has a ring both on the inner edge and outer edge of the rotor.

Im thinking perhaps shabby rotors?

tjts1 · #28 07-03-2014, 04:35 PM

That rotor has either been heavily over heated or thats a crap rotor. I would use this opportunity to get bigger vented brakes off of a W126.

Graham · #29 07-03-2014, 05:08 PM

I have had the same thing happen several times using quality pads and rotors. Problem is that when cast iron rusts, it increases in volume and creates bumps on the rotor surface. Then these hard bumps cut grooves in the pads. Sometimes at edges, sometimes in middle of braking surface. In my case, the initial rusting took place right under the pads when car was stored.

In one case, my e320 with new pads & rotors sat for 3 weeks at Daytona airport, and when I got back the brakes were shot. I replaced pads all round and front discs before driving back to Canada. Discs could have been turned.

Other case was with my 300D and i posted pics of my Saturn rings

WNC123 · #30 07-03-2014, 05:18 PM

Quote:

Originally Posted by tjts1

That rotor has either been heavily over heated or thats a crap rotor. I would use this opportunity to get bigger vented brakes off of a W126.

gotta agree. that rotor is frightening.

is there any kind of DIY thread for this 126 conversion? i have been contemplating it, but don't have enough info to feel confident about doing it.

edit: found these threads:
Upgrading w123 with 1st generation w126 brakes
126 Brakes on 123 Chassis?