Brake help?
 

My wife purchased a 2006 C280.

we put new tires on it and had it aligned. About 700 miles later the brakes started to "Pulse" in the pedal and the steering wheel.

I purchased a front rotors and pad set from FCP Groton. The car was smooth as silk.

Around 600 miles later the pulse started again. I tried "bedding" the pads but to no avail. I then had the front "new" rotors turned. After reinstalling them all was good.

A few hundred miles later the vibration was back. I purchased genuine mercedes pads for the front and rear and had the front rotors turned again. Once again all was well.

The vibration is back again. I noticed a "fluid" coming out from the upper control arms so I replaced the upper control arm bushings.

That did not resolve the issue.

The calipers do not appear to be binding.
The caliper pins are cleaned, lubed and move freely.
I have re torqued the wheels to 80ft pounds with the wheels both hot and cold.
The suspension components seem good and tight. (including tie rod ends).

Any other ideas?

Thanks in advance for your help!
Joe

There have been instances where the aftermarket rotors have metallurgical issues, i.e.; the hardness of the material varies on the wear surface, which causes the discs to wear unevenly, leading to pulsing.

Jim

Agree with Jim. If you put on new rotors and they warped - then you had them trued and they warped again - must be defective rotors. Should be some kind of guarantee on them and the installation unless you did the install yourself.

Cleaning the scale from the hubs with a wire wheel and in extreme cases an abrasive disc, goes a long way to keeping rotors true. There is also a bulletin from MB about applying nickel based antiseize on the hub before installing the rotor to aid in heat transfer from the disc into the hub to prevent warpage.

Thanks for the replies.

The hub to rotor mating surfaces are super clean.

I also serviced the bearings.

The rotors are "Meyle" premium (or something to that effect.) Are these known to have issues?

Thanks

Joe, recommend buying rotors from a MB dealer. By the way MB advises against turning down rotors. If you prefer not to buy brake pads from a MB dealer, recommend using Textar brake pads which are the same soft material as genuine MB brake pads. Granted they produce considerable brake dust, but the brake system performs to design standards.

Ferdman

Rotors from the dealer are the next step I am considering. I am just afraid that whatever is causing this to happen will also do the same to the new rotors.

I did a lot of research on the Meyle (not sure how it is spelled) and found almost non if any, negatives about them.

I am fairly certain the rotors are the issue we are feeling, because replacing them and turning them did solve the problem for a bit. It may be the "Symptom" of another issue.

As I understand it most of your stopping action comes from the front brakes. Could it be that the back rotors (instead of the front) are warped and that you only feel the pulsating on hard stops when a lot of the stopping action is also handled by the back brakes?

Far out guess.

Tyl604

The problem goes away if I turn only the front rotors. I did turn the rears once just to be able to say "I did all of them".

Right now I appreciate any and all far out guesses. :)

Well, just stumped. Still thinking maybe two sets of inferior front rotors - but what are the odds?

I'm always skeptical of a "warped rotor" diagnosis. I'd bet that its among the rare events in the universe. Happens to someone else, never you. But what may happen is that the pads are stcking to the rotors, leaving behind a thin patch of brake material or corrosion. If you don't thoroughly clean a new rotor with solvent before installing, "warping" is almost guaranteed, as assembly oils and rust preventive coatings will burn into the friction surface. Same if you leave greasy paw prints on the rotors or pads. If you park outside in wet weather and don't drive it for a bit, rust will begin under the pads. So this could be a self inflicted problem.

Try this. After a normal drive, whatever that means for you, feel the center of your wheels. Are any of them unusually warm? If so, think stcky caliper. Next time you heve the problem, examine the rotors before you turn them: look for marks or discoloration.

Not so much far out as uncomfortable:
Persistent use of the brake pedal as a foot rest.

Even a small amount of brake dragging, like a sticky caliper, can, and often will, raise rotor temperature enough to cause distortion. Because clamping force is greater at the front, the distortion shows up there first.

Yeah, one common denominator is the calipers. Kind of a "hail Mary" though.

is the caliper working correctly? a binding caliper can do this.

I don't believe buying specific MB rotors will solve the underlying issue unless they are the rotors themselves. Try a different rotor from your local parts store as they shouldn't be that expensive if you are going to buy new rotors because I'm sure every single forum member is not running MB rotors from the dealer on their cars (I'm certainly not) and none are having any issues with theirs. Mine came from AutoZone a few years back and no issues.