What I've found is that slotted and/or cross drilled rotors were developed
back in the early Trans-Am racing days to help increase braking efficiency.
Back then the only brake pads available were of the "organic" design. These
pads work great at low temp, but release allot of gasses as they get hot,
causing the pad to float so to speak on the gas pockets trapped between them
and the rotor. Later, the semi and full metallic helped to greatly reduce
the high temp problems, but the holes and slots are still used to gain every
bit of advantage possible for a race car. The holes are primarily there to
eliminate gas pocketing, and provide a small amount of cooling. The slots
are more of a combo idea, removing gas pockets and, like you said, "shaving"
the pad to help keep brake dust from caking in the pad. If you haul heavy
loads or normally use your brakes heavily (live in the Rockies?), or just
like the look of them, the crossdrilled would be a good first choice. But I
like to keep the maximum amount of surface area on my rotors for those
emergency stopping situations, so I always use high quality stock type
replacements. By the way, about 90% of rotor warpage is caused by uneven lug
nut torque flexing the wheel hub, distorting the rotor as it heat cycles
during normal use. It pays to actually use a torque wrench, or at least
tighten them by hand, to get good even clamping force between the wheel and
hub. And keep that moron at the local auto shop who thinks he's doing a
NASCAR pit stop away from your truck.
Mark
""Carter, Brian"" <brian.carter@texian.org> wrote in message
news:E6C8158CB57C4645A182373B83A028DA049A22@tehuantepec.texian.org...
>
> At 63K miles, the front rotors on my 2000QC are badly warped. I decided
> that I want to go ahead and replace them with better rotors and began
> looking at cross-drilled, slotted, and cross-drilled & slotted.
>
> The vendors of cross-drilled rotors talk about their virtues. They
> confess that early (and poorly designed) cross-drilled rotors messed up
> the vents and weakend structural integrity because there were too
> many/too large holes. Modern, well-designed rotors will have fewer holes
> that are smaller and chamfered. They say the slotted rotors work, but
> wear the pads faster because they act like razor blades on the pads.
> They also say that as the slotted rotors wear, their ability to cool
> decreases significantly because the shallower channels offer less and
> less space to allow gases to expand and escape.
>
> The vendors of slotted rotors talk about their cooling virtues. They
> explain they were developed because cross-drilling reduces braking
> surface area and reduces structural integrity.
>
> The slotted & cross-drilled either offer the virtures or drawbacks of
> both designs depending on who is speaking.
>
> The cost differences are also huge, from as low as $75 to as high as
> $275.
>
> I just want high-quality rotors (not fly by night or slave labor
> manufacturers), that operate at a lower temperature than stock rotors,
> and are less prone to warping. Looks are not important to me,
> performance is.
>
> Any recommendations, including naming the manufacturer?
>
> Thanks,
> Brian T. Carter
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