I just went through the same excercise on my W126. Yes, 0.01 to 0.02 millimeters are not really preceptible.

Now here is a question: How did all of your dial-gaugers keep the rotor from turning while measuring the play? I had a hard time keeping the disk from turning as I tried to wiggle out that .01 - .02 millimeter reading. We aremeasuring play here, not runout at the shaft's end.

Thanks.

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Henry Bofinger
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)

I hope you mean hub and not rotor, or this would introduce another unnecessary variable. The rotor should be off for this procedure.

I don't see how rotation could be a problem. Once it's set up as previously described, you simply grab the hub and push-pull to get a reading. Magnetic base is on the hub.... dial indicator is on the spindle end, measuring in the axial direction. Are you sure you're wiggling correctly? Wiggling should be in the axial direction, not radial.

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95 E320 Cabriolet, 169K

(I hate to re-open this, but I can answer with what I did)

If you can accept my originally posted method for mounting the dial indicator base, look at the picture and you'll see a small spring clamp, one leg shoved slightly into one of the cooling spaces, holding the brake disk/rotor to the backing plate.

Even if you don't accept my mounting method (on the disk/rotor instead of the hub itself), the clamp should still work since the pressure to overcome the tiny spring would be negligible and, IMO, wouldn't affect the reading.

Kestas posted "I hope you mean hub and not rotor, or this would introduce another unnecessary variable. The rotor should be off for this procedure."

Sorry, I don't follow. The disk/rotor part of the assembly can be detached from the hub, but only when off the spindle. Did you mean "caliper" should be off?

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1986 560SL
2002 Toyota Camry
1993 Lexus