Carroll.
I do not agree with your weight theory - my
theory/physics says that the weight saved by drilling
a nominal number of holes is insignificant relative to
the weight of the disc. Plus, each hole reduces the
amount of friction surface achieved, and therefore
reduces breaking by reducing the heat dissipation
area/rate. Breaking is improved by removing the heat
faster from the disc and calpier/drum. Hence finned
brake drums, not drilled brake drums.
Cross drilling and slotting discs are aimed at
'cleaning' the disc surface under the pad - breaking
the water film in the case of wet driving, and
providing a 'sink' location for material removed from
the pad and disc during the scrubbing process. The
dust and metal shavings have to go somwewhere, and
this provides an escape path without it having to
reach the outside of the pad perimeter before being
rejected.
Breaking occurs when the real pad surface is in
contact with the real disc surface - ie the thermal
path is at its best/lowest thermal resistance. Dust
et al in the sandwich acts like marbles on the
racetrack - it is in effect a lubricating film that
works against friction, rather than for friction.
Dust must be removed from the disc/pad, just as water
must be removed from the tire/track interface.
Comments from the List welcome.
Best, Robert.
--- B&C Phillips <bjcap@frontiernet.net> wrote:
> The real reason that rotors were cross drilled was
> to reduce weight for
> racing applications.
> Carroll
>
>
Robert - Yellow 65BJ8
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Cell: 408-221-5244
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