I have one theory, though no way to back it up. I was wondering why such a small amount of runout should cause so much havoc. I'm theororizing it plays games with the ABS system. The warp sets up a faulty pulse, sensed by the ABS sensors, and actually starts amplifying the problem. At 80mph going across Idaho on a trip a several years ago, I thought I was going to totally loose control of the car when I had to hit the brakes hard to make a freeway exit. Scared the snot out of me!! I mentioned that theory to a friend that works at the local NAPA, and a decent mechanic himself, and he said it made sense to him.
Just an idea. Not sure how valid it is.

__________________
past MB rides:
'68 220D
'68 220D(another one)
'67 230
'84 SD
Current rides:
'06 Lexus RX330
'93 Ford F-250
'96 Corvette
'99 Polaris 700 RMK sled
2011 Polaris Assault
'86 Yamaha TT350(good 'ol thumper)

Uneven braking forces will cause serious vibration under heavy braking, and can even cause intermittant lockup and acuation of the ABS. Variations in thickenss get "telegraphed" to the other rotors on the car by the pulsations in the brake fluid, and so you get even more fun stuff as all the rotors start to cause vibrations, all at different times.

Tire foam could have two effects -- corrosion or some other chemical action on the rotor that either causes roughness or wear resistance. Either will result in "warped rotors" if it doesn't wear off quickly. Silicone compounds in "tire shine" produces are usually fairly high melting point dimethyl silane polymers, so they will both lubricate the spot the land on AND reduce wear. Thumpa-thumpa.

I've been lucky, I've only had brake vibration one or two times in 25 years of driving cars with disk brakes. I rarely wash the wheels much, and have never used tire foam or anything like that. Washing the car all the time in an agricultural area is simply silly -- it will be dusty again next day!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

"Uneven braking forces will cause serious vibration under heavy braking, and can even cause intermittant lockup and acuation of the ABS. Variations in thickenss get "telegraphed" to the other rotors on the car by the pulsations in the brake fluid, and so you get even more fun stuff as all the rotors start to cause vibrations, all at different times."


What you describe sounds like what happened to me. Fits the bill.
I figure the $90 it costs me to just replace the rotors every so often is cheap compared to what could happen otherwise

__________________
past MB rides:
'68 220D
'68 220D(another one)
'67 230
'84 SD
Current rides:
'06 Lexus RX330
'93 Ford F-250
'96 Corvette
'99 Polaris 700 RMK sled
2011 Polaris Assault
'86 Yamaha TT350(good 'ol thumper)

I'm sure Benz took rotor problems into account when they designed theirs as thin as they did. Easier to replace them fairly often than to suffer with the weigth and calipers required to use thick ones that have to be resurfaced periodically.

I prefer the Benz system -- nice new rotors every 60,000 miles or so is nice, and still less expensive than turning Americian style one and still having to buy new ones every 90,000 miles at $100 each!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

also never wash your car when rotors are hot, they will warp!!! sounds trivial, but a lotta people do it

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1995 c220 (harness issues sold)
1999 clk 320 cabriolet