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cross drilled rotors Scott Williams is WRONG!



F = uNA


Force of friction is equal to the coefficient of friction, times the normal
force, times the surface area. Bigger breaks will stop faster. Simple
physics. But the question is where the trade off goes the wrong way in terms
of weight added vs stoping power.


aireq

-----Original Message-----
From: scirocco-l-admin@scirocco.org
[mailto:scirocco-l-admin@scirocco.org]On Behalf Of ATS - Patrick Bureau
Sent: Saturday, March 23, 2002 10:47 AM
To: Brett Van Sprewenburg; scirocco-l@scirocco.org
Subject: RE: cross drilled rotors Scott Williams is WRONG!


Bret I would agree for road vehuicules and daily drivers, coudl you explain
why then F1 Racing and Nascar Use Cross drilled rotors if indeed it provide
"now-adays" no evidance of added performance.

inquiring mind would like to know.

ATS - Patrick

=>-----Original Message-----
=>From: scirocco-l-admin@scirocco.org
=>[mailto:scirocco-l-admin@scirocco.org]On Behalf Of Brett Van Sprewenburg
=>Sent: Saturday, March 23, 2002 12:12 PM
=>To: scirocco-l@scirocco.org
=>Subject: RE: cross drilled rotors Scott Williams is WRONG!
=>
=>
=>>Hehehe that got your attention ;-)
=>>
=>>I don't know about performance, I think everyone is missing the point.
=>>Rotors have holes drilled into them in order to increase air flow,
=>>thereby reducing heat in hard driving conditions (such as racing on a
=>>track). That's the theory behind that. I would say (not from experience
=>>since my car isn't done) that they would work...It just makes sense.
=>>Will this increase performance? I don't know, but I do know they would
=>>have to be cooler (temp) no? Of course it could take a couple of seconds
=>>for the pad to grab the cooler rotors (so I've heard). That's why you
=>>would want to get the braided lines to get a better bite in the
=>>caliper...As far as Scott being wrong, I think I have a better chance on
=>>finishing my car today than proving him wrong...
=>>
=>
=>I really need to post that brake article... :)
=>
=>Anyway,  I'm afraid the above opinion is incorrect.  I'll paraphrase from
=>the GRM brake article again...
=>
=>Crossdrilling your rotors does nothing in most situations
=>now-a-days,  except
=>look cool...so please don't say it's for higher performance. (And
=>they do look cool) ;)
=>
=>Rotors were first drilled because early brake pads from the 40's
=>and 50's gave
=>off gases when heated to racing temperatures.  The gasses then
=>formed a thin
=>layer between the brake pad face and the rotor, acting as a lubricant and
=>lowering the coefficient of friction.  The holes were implimented
=>to give those
=>gasses someplace to go.  Todays friction materials generally do
=>not exhibit
=>the same gassing out as the early pads.
=>
=>The holes have carried over more as a design feature than a
=>performance one.
=>Contrary to popular belief, they don't lower temperatures.  In fact,
=>by removing
=>weight from the rotor, they can actually cause temperatures to
=>increase a little.
=>These holes create stress risers that allow the rotor to crack
=>sooner, and make a
=>mess of brake pads - sort of like a cheese grater rubbing against
=>them at every
=>stop.  Need more evidence?  Look at NASCAR or F1.  You would think
=>that if drilling
=>holes in the rotor was the hot ticket, these teams would be doing it.
=>
=>Ok, let's debunk the bigger rotors = better here also (again).
=>
=>Bigger rotors will make your friends think you are cool, bigger
=>rotors look sexy, but
=>bigger rotors do not stop the car.  What a bigger rotor will do is
=>lower the overall
=>operating temperature of the brakes - which is a GREAT idea IF your
=>temperatures
=>are causing problems with other parts of the braking system. (It can
=>also changes how
=>the brakes are modulated by the operator, which might be better
=>for them).  The
=>quick motto is bigger is better until your temperatures are under
=>control.  AFter that
=>point, you are doing more harm than good due to the load of steel
=>hanging on the
=>wheel that needs to accelerate each time the gas pedal is pushed.
=>
=>Finally, SS brake lines only remove compliance from the braking
=>system, which really
=>affects only the pressures and forces applied, not so much how cool
=>the rotor is
=>running...
=>
=>Again, this is an excerpt from a rather extensive braking article
=>from Grassroots Motorsports,
=>written by an anti-lock braking systems engineer with the Robert
=>Bosch Corporation who
=>is a Saturn racer for scR motorsports.
=>
=>In my opinion, this probably doesn't matter to the most of us
=>anyway...very few of us
=>are pushing are cars hard enough to get into the perfomance areas
=>where these kinds
=>of details actually make a difference very often.
=>
=>==Brett
=>
=> \/  '84 Scirocco (ITB racer 2B) | "Hot VW's, take two home.
=>They're small"
=>\/\/ '88 Scirocco 16v (Show), '92 Passat 16v (Winter+) | -
=>brett@netacc.net
=>
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=>Scirocco-l mailing list
=>Scirocco-l@scirocco.org
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