Re: Drilled and slotted disk Q

[16v Jason <jason@scirocco.org>]

That's a good question Brian.
As you no doubt know, the heat created by your brakes can be enormous.  
When the pads and rotors heat up past a certain point, they begin to loose
their effectiveness, usually referred to as brake fade.

You're correct in your observation that slotting, drilled, or grooved
rotors sacrifice precious swept area.  However, their benefits outweigh
their drawback.

The benefit is, of course, greater heat dissipation.  Having grooves or
holes in the rotors allows more cooling air to touch the rotor, thereby
lowering the temperatures of the brake pads, rotors, and brake fluid, and
thus maintaining stopping power as heat builds.

During hard braking, some of the brake pad compound is essentially
vaporized into gasses.  The interruptions in the surface of the rotor allow
the gasses to move away from under the pad itself to surrounding air,
increasing the pad's contact with the rotor and, of course, braking power.

So, in short, the drilled, slotted, or grooved rotors increase stopping
capacity by offering better cooling to avoid brake fade.

Jason


At 03:13 PM 8/6/99 , Captnbr@aol.com wrote:
>I have learned in aircraft performance classes that brakes stop aircraft
(and 
>cars for that matter)  by changing the forward momentum energy into heat 
>energy with disks and pads.  The greater the surface area of the disks and 
>pads, and the greater the friction, the greater the heat energy created
which 
>equals greater stopping capacity.  So why would drilling and slotting rotors 
>and disks aid in braking.  Aren't you decreasing the surface area causing 
>less friction to be created.  Why are slotted and drilled rotors better?  
>Inquiring mind wants to know
>
>Brian 86 16v
>
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----------
1987 Scirocco 16v
1989 Mercedes 190E Sport Euro


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