Larry may have a point, but I'd bet on the Balo brand rotors being the culprit. The Balos I had on my 92 400E didn't last long at all before they warped. I don't ever plan to try that brand again...

I am presently running ATE Power Slots on the car, but I'm not happy with the noise they make under hard braking conditions.

My shop says I should only use MB Brand rotors...

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)