W210 Front Brakes Dragging - how to adjust?
 

Cleaned up and refinished couple wheels this past weekend, mounted a couple new tires, was putting them on and noted that the front brakes seemed to be dragging a little. As I spun the wheel there was a little drag and the sksksksksksksk type noise. Took it out for a spin, warmed the oil up for an oil change, got that going and happened to touch the front wheel and it was hot. Not pull your hand away but significantly warmer than the rears, did some braking but not a major thing.

How do I adjust these. A brake man I am not.

Thanks

There is no adjustment on standard disc brakes. They'll always feel a little warm after a drive because the pad is always resting against the disc. Not pushing hard against it, but just gently resting, waiting for you to push the peddle and put them to work.

Was the "dragging" side hotter than the other? It's rather hard to drive a car without using the brakes, and thus heating the front rotors. Remember that the fronts produce about three times the heat of the rears.

If it is dragging, it's most likely either the caliper sticking or a faulty flexible hose.

If you can get at least one or 2 spins out of the wheel then it is OK. As stated, on disk brakes, the pad will gently rub the disk when the brakes are released but there is almost no pressure on the pad and there is not enough friction to generate any heat or do any wear on the brakes.

My W210 has clips on the front calipers that affect how snug the pads are against the rotors. You may want to play with these clips a little or at least inspect them.

It could be the wheel cylinder seals, they are designed to flex and roll a little so they move the pads away from the disc. If they have lost their flexibility the pads will stay against the disc. I've had calipers stick too, they just need cleaning and lubing.

And, how is your pad wear?

Pad wear is fine, but it has probably only 6,000 since changed. Could redo and reclean etc. I'm probably just being too picky.

Thanks for the information.

Disc brakes, unlike drum brakes are designed to have a slight drag. There is no spring to return the pad to the rotors. As long as the car is braking straight and not pulling to one side, keep an eye on wear.

You will probably be just fine.

Drive your car a few miles without applying the normal brakes to stop. Use the emergency brake instead. Get out and feel both front wheels. If one is not noticably warmer than the other you are pretty sure all is well. Now if you are only getting six thousand on a set of pads something is probably also wrong. Pretty simple and pretty conclusive.

One thing you may notice is that the inner pad is clipped into the caliper piston. The piston seal will actually allow the pad retract slightly and lose its contact with the disk. The outer pad is mainly the one that rests against the disk. If you raise the car up and move the wheel around slightly with your hands, you will find that it will slightly knock the outer pad away from the disk and it will rub less.

Try it, raise the car up, you should get a couple of free turns out of the wheel. Kick the tire as is it were being moved (careful not to bump the car off the jack) and torqued during driving and you will find that the brake will drag a lot less. When you are driving the car, the brakes actually drag less than you think they do because the motion of the front wheels pushes the outer pad back ever so slightly.

If your rule out all other possibilities and it is in fact the calliper not retracting, your only real option is to rebuild or replace. My guess is that being Mercedes, the replacements are spendy.

The problem is often corrosion on the piston. cleaning it up with emery cloth will often do the trick. Make sure your seals are in tact or this repair will be short lived.

Good luck,

Wayne