Chessie

E320 Bluetec, 2007 -

I usually drive pretty conservatively, but noticed that lately, when I brake firmly, there is a thumping coming from the driver's side front wheel. Next thing I know, my left front is grinding.

So I ordered new pads and rotors and replaced front two brakes and rotors.

I noticed that the pads on the passenger side were only 1/2 worn out (if that) while driver's side was down to the metal.

After replacement, I noticed that the driver's side is thump-thump-thumping during almost all braking. (I don't notice it if I brake slowly, because the radio is on, or the windows are open, the wife is berating me, whatever...) If I stop moderately, or strongly, or panic stop, the thumping is pronounced.

I'm assuming that this is the anti-lock brake system engaging too often and causing the driver's side brake pads to take a lot of the braking weight and wear out unevenly (relative to the passenger's side).

Note, there are no CEL's or warning messages.

This is strange behavior to me, but I'm guessing that the driver's side Speed Sensor is to blame and I've ordered a replacement...(waiting for it to arrive)

Does anyone else have any other suggestions on what might be causing this?

Thanks,

Chessie

Plutoe

Based on what you have provided, this sounds like another we ***** wonka brake job. The only question I have is did ***** use factory or equal diagnostic equipment to check for faults, deactivate the braking system correctly install the pads, activate the braking and learn in the new pads----if the answer is no, then have ***** do the job correctly, however if you were of a mind set to do the job as cheap as possible---well then you have met you short term objective---now you will have to find someone who can do the job again but correctly!!

Efivehundred

Plutoe, does an 07 W211 have SBC?

OP, I think if it was your speed sensor you would have an ESP warning in the IC. Is there any play in the wheel, top to bottom? Before replacing any parts you should have it scanned for faults.

Chessie

It looks to me like the control unit is NOT an SBC, and it does NOT have SBC cast into the metal, like I've seen on some other post's pictures. It *is* in the front passenger side of the engine bay with the four metal brake lines coming out of it....

I'm not getting any check engine lights or warnings, but I have *not* had it read for codes.

I don't notice any play in the wheel... the thump-thump-thumping is directly related to how hard I step on the brakes. I'll raise the wheel again this evening and see if the bearings seem normal with no play. I had real difficulty getting the rotor off, I had to use a gear puller and it popped off.. I didn't notice any play then.

Why would one side wear out so much more than the other and wouldn't the rapid thumping during hard breaking be the ABS kicking in?

tnx...

Plutoe

I have changed the post to read "braking" system---I could GAS what you call the system you need the correct diagnostic equipment to diagnose, find fault, learn in and assist in corrective action--lets call it the FBS!!