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Re: Not Really re.- Rotor Hex Bolts

The discussion on rotor hex bolts and the posting in digest #77 has motivated me
to comment on my experience with warped rotors.

I have owned an '86 524TD since 1990; I have a Dinan Stage 3 suspension in this
car, I drive through a mountain pass every day (fast), and I had repeatedly
warped my front rotors until recently. This car has an auto trans (I think all
TDs sold in the US came this way), so there is almost no engine drag going down
hill, even if I manually shift the trans into a low gear. Also, the diesel
engine may be heavier than the gas version (not sure about this one).

After complaining bitterly about warped rotors to Dinan, they installed a
mondo-sized front brake set from (I was told) a euro-version 850 "stretch
limo." The rotors and calipers are substantially larger than stock 5 series,
and the car stops *very* quickly. However, I warped these rotors in about 2
weeks. Then Dinan asked me if I wanted to participate in some R&D, and they
sent a set of rotors out to have them heat treated (apparently, they have had
great success in heat treating exhaust manifolds for gas turbo cars that would
warp with the heat produced by the motor on new turbo installation until heat
treated). I warped the heat treated rotors in about a month. After than, I
lived with the warped rotors for about a year, until I couldn't stand it any
more. I returned to Dinan, and begged for some sort of engineering solution. At
that time, they had been experimenting with carbon pads with some of the
racers, and suggested I give them a try.

So, I had them cut my rotors flat again, and I have been running the carbon
pads for several months now. I have not detected a hint of warpage since
putting these pads in... I have seen a Cool Carbon ad indicating that their
pads run several hundred degrees cooler than stock or other aftermarket pads--
I now believe these claims. Pedal effort, after a brief warm up, is very
acceptable (similar to stock pads), and if you can live with the thick, black
dust and occasional squealing from the pads, this is the way to go to cure the
rotor-warp blues.

- -cb

86 524td, Intercooled, worn-out left front armrest, no more warped rotors.