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.

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Fred Hoelzle