If the rotors are still within spec try another set of rear pads and put some brake paste on the back of them.

I would never consider turning rotors on these cars, they are pretty thin as it is. Besides MB brake rotors are cheap, rear rotors for my W126's can be had for $30 each. Don't mess around do the job right.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200