Are these rear brakes doing anything? - PeachParts Mercedes-Benz Forum

DonB · #1 07-21-2007, 09:10 PM

I've had a warping problem with the brakes of my 1999 C230 for some time. I get the front rotors turned, they're good for a couple of months, then they start to pulsate again. This has happened twice, after I replaced everything (all rotors, rear calipers, pads).

Anyhow, last weekend I turned all four rotors, replaced the front pads (epg green), and cleaned up the rear pads. Working OK now, but look at the pictures after a week of driving (about 600 miles). The rear rotors are rusty! Is this normal or is there something else going on here?

The pictures are: Front brakes dusting like crazy, rear rotor rust, rear rotor rust, front rotor is fine.

Parrot of Doom · #2 07-21-2007, 10:36 PM

Looks to me as though you have the wrong pads on the back.

t walgamuth · #3 07-21-2007, 11:08 PM

The only real rust on back is where the pads are not rubbing the rotor.

yeah, maybe the pads are too small.

Tom W

Ferdman · #4 07-22-2007, 05:12 AM

Don. MB recommends against turning rotors ... buy new ones. It's relatively inexpensive to buy genuine MB rotors from a local MB dealer. As for brake pads I would buy either genuine MB pads from a local MB dealer or Textar pads online. Confirm that your rear brake calipers are functioning properly by jacking rear wheels, putting the transmission in neutral, then have someone apply the brakes while turning each wheel. If there is a problem try bleeding some brake fluid from each rear caliper to verify that the brake hoses aren't restricting fluid flow. Assuming the brake hoses are fine remove the calpers and check that the piston retracts easily. If not, you may need to rebuild or replace the rear calipers.

t walgamuth · #5 07-22-2007, 05:17 AM

I agree with ferdman, too.

Tom W

DonB · #6 07-22-2007, 10:52 AM

So, I take it that everyone agrees that something is wrong, this is not normal. OK, good, I should reply to the suggestions:

Parrot of Doom - I don't know how that could happen. I ordered the parts based on make, model, vin, etc. They seem to fit properly (slide in and out of the caliper) and seem to cover the rotor properly. When I installed them, they appeared to be exactly the same as the original pads. Is there a way to verify the size is correct, or maybe I should just order a different set and try them out?

t walgamuth - Yes, there's more rust on the outside edge, but if I had a really good picture we would see that the whole surface is rusty (but more on the outer edge). The really interesting parts is the surface where the pad mates. It looks like the machined surface from the turning hasn't been worn off yet, implying that the pads aren't pinching the rotor.

Ferdman - That's what I thought. They aren't very expensive, so I bought a set of four Brembo's (OEM I think). Unfortunately, it ended up doing the same thing, so I haven't done any more rotor replacing since. On pad brand, wow, there's a lot of comments out there. The OEM Textar brand seems to have a reputation for dusting, so I went with Wagner, then EPG's. All had pretty much the same result, so I didn't think this was a pad quality issue.

I already replaced the calipers and had the same result. The original calipers were really bad, so I was sure that would fix it. Maybe bleeding them again would do something.

Pictures are the rotors before the latest turning - outside view, inside view

Hatterasguy · #7 07-22-2007, 11:25 AM

Those rotors look warped, I think Tirerack had a good article about why disc's warped in that fashion.

Brembo discs are totaly junk, I can't think of worst discs. I'd throw them out and get some OE's.

Pads are pads.

manny · #8 07-22-2007, 12:10 PM

Possibly another overlooked problem.
The piston on the rear caliper has a " step " in it ( where it contacts the pad ).
This step must be adjusted ( by rotating it ) to, I believe it is a 20 degree angle.
MB uses an angle gauge to set this.
That will ensure complete 360 degree contact ( uniform pressure ) between the piston and the pad.

DonB · #9 07-22-2007, 01:11 PM

Hatterasguy - I agree, they don't look so good. When I bought them, I thought Brembo was OEM. Come to think of it, the parts guy at my local MB dealer said Brembo was pretty good. Maybe he's confused. So, which brand should I try? I've seen ATE, Balo, Brembo, Zimmerman, Genuine, OPparts, and whatever the dealer offers. Most of the brands run around $35-$40, dealer is about $50.

manny - Good point, I wondered if there was a trick to proper installation. How do I get the proper piston alignment done? Is it obvious, or do I need a dealer or .....?

manny · #10 07-22-2007, 02:50 PM

If you look at the face of the piston, right here:
http://img.eautopartscatalog.com/live/N1040110891ATE.JPG
you will see 2 distinct marks at about 12'o clock and 4'o clock position.
Have a look at your calipers & see if the raised portion of the piston is anywhere near a 20 degree angle.
In my experience, I would opt for brake discs from the MB dealer, or buy Zimmerman.

mpolli · #11 07-22-2007, 03:17 PM

One fairly easy way to verify brake function is by temp. Start off with a cold car (sitting overnight). Then drive a short distance, maybe a mile, and hit the brakes from 40 mph a couple of times. Then park the car and measure the temp of the discs. This is easy if you have an IR thermometer. Otherwise you can just use your finger (carefully). Any too cold are not working and any way too hot are siezed. Temps should be equal left to right and the front will be a little hotter than the rear since they do more work.

Mike

Hatterasguy · #12 07-22-2007, 07:48 PM

I'd go with the dealer. I have had decent luck with ATE but I have always been told the dealer is the best. From my understanding MB gets the good discs and the aftermarket guys may be selling discs that didn't quite meet MB's spec.

DonB · #13 07-22-2007, 09:18 PM

manny - I remember seeing the caliper and wondered why it had the cutaway. Are the marks you mentioned on the caliper?

mpolli - Thanks, that's a great idea. I'll try it next opportunity.

Hatterasguy - You might be right, I've heard that same thing about tires (I work in the Akron area and know lots of tire experts). If I replace the rotors, I'll go to the dealer this time.

Sounds like I have plenty to try next weekend. I think I'll do the free stuff first (measure temp, check piston orientation, etc). Thanks everyone for the help, I'll let you know how it works out.

cf · #14 07-22-2007, 11:03 PM

Quote:

Originally Posted by DonB

I've had a warping problem with the brakes of my 1999 C230 for some time. I get the front rotors turned, they're good for a couple of months, then they start to pulsate again. This has happened twice, after I replaced everything (all rotors, rear calipers, pads).

Anyhow, last weekend I turned all four rotors, replaced the front pads (epg green), and cleaned up the rear pads. Working OK now, but look at the pictures after a week of driving (about 600 miles). The rear rotors are rusty! Is this normal or is there something else going on here?

The pictures are: Front brakes dusting like crazy, rear rotor rust, rear rotor rust, front rotor is fine.

On our w202 I did not have good experience with EBC green on MB rotors.
Either the EBC green is too hard for the rotors or leave deposit on rotors.
Changed back to MB pads and never had problem since.

2dino

Hirnbeiss · #15 07-23-2007, 07:31 AM

The rear rust looks like it's on the outside circumference - to be expected if the pads don't contact there. Like Tom W said, if the pads are too small, worry, otherwise I would only concern myself with the front warping issue.

Have you replaced the front bearings at any time? If so, make sure the inner races are seated square, bearing play is correct, and that the rotor sits evenly flat against the hub (i.e. no rust buildup on the hub face). Then new rotors & a good bleed up front.

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