I've had it twice now.

This time I was sure it was the front stay rod bushings again, a problem when I got this car 11 years ago, replacing them with IPD's blue poly version. Problem solved. But could those polys be bad now? They looked OK, so I went at the front rotors (based on feel). There I saw pad deposition marks, which I tried to erase with a rotary wheel sander, but the wheel-speed vibration persisted.

Then, when my son suggested the Rear rotors, I had a 15-year flashback to a friend's 240 with the same shaky symptom. That one had voids in the 1/2" wide rust band that circled a rear rotor near the hub. The pad would catch a void every time it came around. Chipping the thick rust band off helped some, but new rotors finally fixed it.

Now recalling that occasion, I pulled the 940's left rear rotor to find what's shown in the photo below – a flaked off chunk of rust (on the inside) leaving a tell-tale void/gap only about .010" deep.

Two days later I had a pair of Meyle rotors (China) and Volvo OE pads (India) from eEuro, one of set of which went immediately on the Left Rear. That test drive was fine, but both sides were replaced.

Braking shudder caused by rust flake "void" - LR Rotor, inside surface.







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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.