Brakes

[eperson@students.uiuc.edu (Eric Person)]

Not to start up this discussion again,
but while i dont dispute the fact that X-drilled rotors have a greater
overall surface area, I am not sold on the claim that this will cool the
brakes faster.  It would seem that the holes would not greatly increase the
effective convective heat transfer surface area, since the added surface
area from the holes is basically inside of a small cylindrical hole and
probably does not get sufficient airflow over this surface to transfer any
significantly greater amount of heat than a stock rotor. It would seem that
this combined with the reduced thermal mass would make a x-drilled rotor
not an improvement over a non drilled one for most applications.   Maybe
with some very well designed brake ducting, it may be possible to get some
flow across the rotor(normal to the surface) but that is beside the point.
Anyone have any other ideas or any real data to show the superiority of
x-drilled rotors?

Eric Person
86.5 16v      

>pro - they have more surface area and will cool faster between braking
events (as well as heating up
>slower during braking, attempting to counteract the less thermal mass
thing). This is good for the
>guy making frequent 20-40 mph drops in speed (i.e. on a track)... during
the short stops the rotor
>doesnt heat up enough to have a noticable effect on the pads coefficient
of friction. The rotors
>will cool quickly between braking events, making them better for frequent
braking (where the solid
>rotors would just heat up more and more every time the brakes are hit).
>
>aside - drilled rotors that are intended to be used under heavy racing
conditions need to be made of
>an alloy that will resist warpage under the increased thermal stresses
from the faster heat/cool
>cycles that the rotor has to live through. over the years, stock rotors
have better mixes of metal
>in them and can deal with the stresses of being x-drilled (to a point).
>
>bottom line - unless your intent is auto-x or some kind of track racing
where you will be on the
>brakes heavy and often, dont waste your cash on the x-drilled rotors.
>
>note - I'm putting brembo x-drilled/slotted/plated rotors on the rieger
here shorty, but i am doing
>so solely for the looks (gonna have 17's with a BUNCH of open space in
there, and i REFUSE to look
>like the cheey ass hondas/neons at work with 18's showing off their rear
drums.
>
>Allyn Malventano, ETC(SS), USN
>87 Rieger GTO Scirocco 16v (daily driver, 170k, rocco #6)
>86 Kamei Twin 16V Turbo Scirocco GTX ('it has begun', rocco #7)
>87 Jetta 8v Wolfsburg 2dr (daily driver, 260k, 0 rattles, original clutch,
driveshafts, wheels :)
>
>
>----- Original Message -----
>From: <JoshuaA.Conner@VerizonWireless.com>
>To: <scirocco-l@scirocco.org>
>Sent: Tuesday, April 23, 2002 9:34 AM
>Subject: Brakes
>
>
>> i know this has discussed before, but it seems the crossdrilled theory is
>> that it's not really all that effective right? (compared to slotted)  My
>> wonderings aloud are this:  i was recently at the local high dollar Lotus,
>> Porsche, Ferrari, Aston, and everything else high zoot dealershit and I
>> noticed all the over $50k cars with x-drilled not slotted.  Why this? no
>> flame wars plz, just dialogue  :)
>>
>> Joshua Conner
>> OH//Customer Care, ext.  6165
>> Verizon Wireless
>> coolj@vtext.com
>>
>>
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>
>
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