Alan Myers wrote:
>What about having the rotors cross-drilled (in a radial pattern) instead
>of grooving? I would guess the biggest part of brake fade comes from
>overheating of the pads and rotors, anything that would help reduce heat
>would help reduce/prevent fade. Motor cycle shops can do this and it
>sounds a lot simpler/cheaper than the grooving you descrbe.
>
>Also, on my TR4, I simply removed the dust shield behind the rotor to
>improve cooling. I also like the semi-metallic pads (I always get the
>best semi-met. I can find, not the budget brands) & would only consider
>the kevlar/carbon/un-obtanium/kryptonite/diamond-coated type for actual
>racing due to high wear on the rotors.
I've got a buddy that cross-drilled his rotors on his Datsun 510. My own
theory is that cross drilling has the MAXIMUM effect if the rotors are
vented, i.e., between the two opposing rotor faces there are channels that
collect dust and hot vapor from the dilled holes in each face, the channels
radiate from the center of the hub.
My understanding of "pad fade" is that the heat becomes so intense that the
pad material is vaporized and this "vapor" actually forms a barrier between
the pads and the rotor surface. Result: No brakes. (but the pedal stays
firm) Grooves or holes are more for evacuating this vapor from beneath the
pads than it is for actually relieving heat.
I have doubts about cross-drilling, mostly in that I'm not sure what it
does to the strength of the rotor. It would seem that short of getting
some vented AND cross-drilled rotors, grooving the rotors would give the
most results in terms of evacuating that hot gas and vapor from the pad
surface while still maintaining the strength of the rotor.
One thing that should be pointed out here... heat in brakes is not a bad
thing. You do NOT want "cool" brakes, because if your brakes are cool,
then you're probably not stopping very quickly. The brakes' job,
literally, is to "convert" to kinetic energy of a fast-moving car into
HEAT. This "conversion" results in slowing the car down, of course. The
challenge is not so much to keep the brakes cool as it is to allow the
generation of heat while providing a way to dissapate the heat and vapor
quickly so as to prevent the other side-effects of heat. It's very close
to the same thing as "cooling" the brakes, granted. You may think I'm
splitting hairs. Well, I am!
Pete Chadwell
1973 TR6
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