Jim Perry

Volvo Enthusiast
So I am having a debate with a friend about brake rotor size(diameter and thickness). To the point: if a race car slows adequately and the brakes do not fade, does using larger brake rotors and pads on that car have the potential to improve lap time? Maybe another way to say it using a concrete example, if one must start braking at marker 3 going into Road America's Turn 5 in order to slow enough to not lock up the brakes, would larger rotors and pads allow the same car/driver to wait until, say, 2.5 before beginning to brake?


VRO Principal
Staff member
I'm certainly no expert, but this is how I understand it (I'm happy to be corrected if this is not the case):

If your race car can lock the brakes up, you have plenty. (increasing traction might overcome this, but let's assume you are already running the widest/stickiest tire you can in your class) Increasing the rotor diameter will not decrease stopping distance in one corner, but will keep things cooler meaning your brakes will work as designed for a longer period of time. -The larger diameter rotor will dissipate the heat better than a smaller one.

On the down side: larger brakes are heavier, so going too big can actually increase your lap-times.

My only experience: I used to track a 993 street car (3k lbs). With stock diameter rotors and track pads, I would see cracking between the drilled holes after 2-3 days at RA. After I installed "Twin Turbo" brakes (which were significantly larger), the cracking stopped and my pads would last way longer... My temps also dropped drastically.

Only downside (besides weight): On the street, the pedal feel sucked.


Crazy about Datsuns
A larger brake rotor could possibly help lap times? On the other side, the driver would have to be very consistent with their braking to see if there was truly a benefit. For endurance racing, larger rotors and brake pads are a great benefit. They allow longer changes between changing pads.


New member
I run better brakes albeit Vintage legal brakes. I like the idea of having more reliable and higher quality brakes on my car for obvious reasons. The salesman claims better feel at the edge of locking up the tire I cannot say I notice anything different. I find brake bias and car set up has a much larger effect than what brakes a B-Sedan car is using. I have heard from group 6 people with heavier cars i.e. Corvettes, Mustangs etc that modern brakes do effect lap times and supposedly the brakes they used in the day are prone to fading on the track and lose their effectiveness to more modern better designed brakes which makes sense. But to worry about brakes on formula Fee, Fords, MG's or basically 2.0L and under is a waste of time IMO.