Are these rear brakes doing anything?

[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.

[Parrot of Doom]

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

[t walgamuth]

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]

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]

I agree with ferdman, too.

Tom W

[DonB]

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

[cf]

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]

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.

[PerkHouse]

Manny,

Sorry to be so dense, but I don't quite understand. I get that I rotate the piston, but... 20 deg angle from what to what? From the marks? Which one? To what? To horizontal? To vertical?

Thanks!

[manny]

PerkHouse,
Quoted directly from the book:
" Prior to pushing the piston into the caliper, position it so that its raised section will be positioned uppermost when the caliper is refitted.MB dealer use a special guage to ensure that the piston is correctly positioned.
The purpose of this procedure is to have the piston contact the pad, contacting the rotor at a slight angle, to reduce the possibility of brake squeal. "
The picture shows the caliper ( in a mounted position, with the raised portion of the piston starting at 9'o clock and, going clockwise, ending at the 4'o clock position ).
Make sense?

[PerkHouse]

Now that I've done it... yes, it does make sense. Thanks! I reconditioned my front right, but when I got to the front left (@ 10:30 last night) I realized it was not an ATE. I don't know if it's a Bendix or a Girling and I don't care, but it has a seized piston, so I've ordered a reman. I know, I know! I should replace both the fronts as a set, but I'm a beginning teacher (at almost 42) so the average salary for high school graduates in NC is higher than mine. (not much, but still...)


By the way, my rear calipers each had a seized piston, so I installed some Cardone remans last week. Cardone did NOT position the elevations correctly. In fact, 2 pistons were in random positions and the others were upside down. And one of the pistons they used, though it seems to be the correct size, was apparently not from an ATE caliper --or at least not from the same year-- because its elevation marks were about 180 degrees apart instead of about 240/120 degrees. The other thing is that one of the rubber dust caps on one caliper was deformed and pinched by the retaining ring and the other one had a small hole in it.

I wonder if Beck/Arnley pays attention to these little details more closely. It might have been worth the extra cash to not spend 30 minutes repositioning those 4 pistons. That and the fact that the non-rust finish was scratched in the process. (Don't these re-manufacturers do any research? Don't they wonder what those elevations are for???)

[manny]

Originally Posted by PerkHouse

(Don't these re-manufacturers do any research? Don't they wonder what those elevations are for???)

I like yor sense of humor.
Don't you realize, the IQ of the average " Rebuilder " is somewhat less than room temperature ( measured in degrees Celsius ).
You're lucky the pistons were not installed backwards.

[DonB]

First, my apologies for the long delay in getting back to this, my kids came home from school and dominated all my time.

I finally had a chance to check the alignment on the rear brake pistons. They were a bit rusty, so I cleaned them up before reassembling. Manny, does the alignment on the pistons look correct? Thanks again for the help,

Don

tn_IMG_1696x.JPG - Drivers side rear, in-board piston
tn_IMG_1698x.JPG - Drivers side rear, caliper about to be installed
tn_IMG_1699x.JPG - Drivers side rear, both pistons
tn_IMG_1706x.JPG - Passenger side rear, in-board piston
tn_IMG_1708x.JPG - Passenger side rear, both pistons

1999 C230 Kompressor