Brakes are grinding - not pads
 

1978 300D
I'm getting grinding sounds when I brake at slow speeds. I haven't done anything to the brake system, and I've checked the pads and they're good.

I've read stuff on here about sanding down the rotors and/or the pads. I guess it comes from a smoothness of the two? Any thoughts on what the griding is and how I can fix it?

It could be a bad wheel bearing. They will sometimes make a grinding sound during brake application.

it also could be the rear e-brake shoes dragging. be sure and pull the rear rotors and inspect the e-brake shoes.

I have the same thing, I'll check bearings and probably have the rotors turned. Sometimes after some hard braking the rotors sill get hard spots and that can make a noise, as well as eat grooves in your pads.

Interesting. I have the same issue with my 126 - Just replaced everything brake related and I have a similar grinding sound. Are there any other symptoms of bad wheel bearings?

It was the left rear inside pad. So I need to replace it. I got it out without moving the piston - how do you move the piston back?

To move the piston in, use a vice grips or channel locks and the old pad, grip against the caliper, and squeeze the pad in toward the caliper. It may make it easier to pop the cap on your break fluid reservoir (to allow the pressure to get out).

Other people have suggested using a thick heavy screwdriver and using it as a lever to push the piston and pad back in, but I have never done it that way, so I don't quite know how that goes.

If it is just one pad worn, either someone did an incomplete brake job (not very likely?), or you may have a piston that is sticking.

Just one pad wearing may indicate a stuck caliper piston. Check bearings, jack up car, and put your hands at the 12 o'clock and 6 o'clock position and alternately push/pull, no play allowed! Then spin to see if you hear anything.

Sure its not a dragging dust shield?

Sounds easy enough.

This may be the case. What should I do about it?

Big thanks

12 & 6 o'clock of what? Also, how do you check bearings?

Think of an old analog clock. 12 is up top 6 is at the bottom.

When my bearings went bad, there was no play, but spinning the wheel felt and sounded like spinning a very quite ratchet wrench, and I could feel the wheel try to stop with each "click".

So I don't have to stay up 'til midnight to check my bearings?

The tire.

well, I appreciate the help folks.

The problem looks to be a stuck piston causing the rear inside pad to wear down which caused the grinding.

I've got to figure out how to fix the piston. My bad, the title should be changed as it is the pads.

Any tips to fix a stuck piston?