Re: 1990 GT Rotors and Calipers

dwight wrote:
".boB" <bobcowan@xxxxxxxxxxxxxxxxxxxxxx> wrote in message news:44ff5d6f$0$21437$ec3e2dad@xxxxxxxxxxxxxxxxxxxxxxxxx

dwight wrote:


I have aquestion about rotors and calipers on a 1990 GT.

Slotted/drilled/dimpled rotors are for looks only. They actually decrease brake performance over a stock type solid rotor. It's all about surface contact area.

Oh, I have to disagree strongly with this. In theory, that may be true, but the stock Mustang rotors on my '93s were CRAP. The PowerSlots GREATLY improved braking on both of my cars.

Think how much better they would be with more surface area.


I think more about heat. As in the voluminous clouds of white smoke coming from my stock rotors.

dwight


Then something is wrong. I use a stock replacement solid rotor front and rear. I spent the day at the track yesterday; really wailing on those brakes. Hard into turn one from 130 to 60 in about 2-3 car lengths. Over and over, 30 minutes at a time. They smell good, but never smoke.

Brakes work by converting rotational energy into heat energy through friction. Greater friction occurs with increased surface contact area. Cutting slots and drilling holes decreases surface area of the rotor. It's like saying, "I need better brakes, so I'll install smaller rotors." Doesn't make sense.

The original purpose for drilling and slotting rotors had nothing to do with temperature control In the olden days, racing pads would outgass under heavy use. The gas pocket would get trapped under the pad, and prevent contact. The holes and slots were there to allow the gas to escape. Modern brake pads don't outgass, so there's no need for that. Modern replacement rotors are drilled/dimpled/slotted because people like the look, and don't use their brakes enough for it to matter. They're for the ricer and wannabe racer crowd.

Brakes that need extra cooling should have a better vanes, and more air flow into the center of the rotor. That's how cooling occurs.

For more information, look to the FAQ pages of companies like Baer Brakes and Wilwood.

But, if you really think you get better braking with smaller rotors, then one of two things happened. 1. Your brakes were so bad before that almost anything would be an improvement. Or, 2. You've spent all that money on bad decisions, so you'll stick by your guns no matter what, facts be damned.

--
..boB
Arrived: 2006 FXDI, Red.
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1966 Mustang Coupe - Daily Driver
1965 FFR Cobra - 427W EFI, Damn Fast.

.

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    ... decrease brake performance over a stock type solid rotor. ... As in the voluminous clouds of white smoke coming from my stock rotors. ... I use a stock replacement solid rotor front and rear. ... Brakes work by converting rotational energy into heat energy through friction. ...
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