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There is a lot of conflicting information whether slotted or drilled rotors perform better than blank rotors. For a street car that will do the occasional track day, which type of rotor should I get?

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There really isn't enough information here to give a definitive answer. Which particular street car? Top speed? Weight? Which track? If you can't define why the answers to the previous questions are driving your purchase of rotors, the answer is: get better tires. –  Bob Cross Mar 26 at 11:33

4 Answers 4

up vote 12 down vote accepted

I would recommend you get slotted, but not drilled rotors. Regular rotors will work fine for typical track use. What is more important is the type of brake pad you purchase to go with your disks. The reason I suggest not getting drilled rotors is, they have a tendency to crack at the holes due to stress risers. They will not last as long as you'd like them too and will not give you much more performance than just the slotted ones will. The slotted rotors will provide space for allowing brake dust and such to be brought away from the pad, which keeps it clean and better intact with the rotor.

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Thanks @Paulster2. I read something about slotted rotors chewing away pads quicker. So this isn't an issue in this case? –  SimpleSimon Mar 26 at 1:21
    
I would imagine they would chew them up slightly faster, but the trade off is worth it. What happens is on regular flat brakes (no slots or holes) the pads will form gas under them under hard braking. This will cause you not not have as good of stopping force. With the slots, it gives the gas somewhere to go. –  Paulster2 Mar 26 at 2:04
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Slotted rotors due indeed eat up pads the fastest, but perform the best. They also tend to have less cracking issues than drilled. I only run solid (surface, they are vented) rotors on my track car though. They're plenty good enough (can lock up wheels with them if I care to push hard enough on the brake pedal), have more thermal mass, don't exhibit the excess wear of drilled or slotted, and also have less cracking issues due to more even heating/cooling. –  Brian Knoblauch Mar 26 at 16:28

Contact area

Blank rotors have a larger area in contact with the pads than slotted or drilled rotors. Therefore they provide better braking at the same temperature.

Cooling

To cool the rotor, manufacturers use a vented rotor, not a cross-drilled or slotted rotor.

cross-drilling puts holes perpendicular to the flow of air - they have no cooling effect whilst the wheel is turning.

A cross-drilled or slotted rotor has less thermal mass and thus heats up faster and fades faster.

Dust removal

So far as I know, with modern rotor and pad materials, dust removal is not a significant factor affecting brake performance.

Gas Removal

I can find no scientific evidence that the resin in overheated pads outgasses faster than gas is removed by rotation. (e.g. see cross-drilled rotors myth)

What is used by people for whom performance is more important than looks?

enter image description here
Image from formula1.com The brake rotor on an F1 racing car is not cross-drilled nor slotted.

enter image description here
This undrilled, unslotted brake rotor stops a 100-ton vehicle from 185 MPH in 2500 feet of tarmac.

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Using F1 as an example is pretty telling. They're dealing with much harder engineering problems than the rest of us. –  Bob Cross Mar 29 at 20:39
    
Careful though, they use different materials. Where road cars use steel rotors, F1 cars use a Carbon-composite material that is much better at handling and dissipating high temperatures. –  Juann Strauss Mar 31 at 9:37
    
Thanks RedGrittyBrick. Are you able to comment on the gas that @Paulster2 mentioned? –  SimpleSimon Apr 2 at 11:48
    
@SimpleSimon: see updated answer. –  RedGrittyBrick Apr 2 at 13:48
    
It is of note, that the above F1 picture is circa 70's technology. Newer F1 brakes look more like this, circa 2013. There aren't any slots in it, either, but you won't find slots/holes in carbon fiber disks. –  Paulster2 Apr 7 at 11:04

Blank rotors provide the best braking during regular operation. Slotted rotors are such because they improve performance during heavy and prolonged braking. If it were my car, I'd rather spend the money on high-heat racing pads and race-grade brake fluid (which boils at a much higher temperature).

Other things to consider are steel braided hoses and modifications to your front bumper to allow lots and lots (and lots!) of extra air to flow over your brakes to keep them cool. If you hate your car's looks enough, you could also modify the rear body panels for the same purpose. This is usually accomplished in conjunction with light alloy wheels with the thinnest spokes possible. And remember: trail-braking and heal-and-toe are your friends. Trail-braking allows you to let up off full braking earlier and heal-and-toe shifting allows the gearbox to slow you down a bit, while also putting you in the right gear for the exit. These two techniques combined will simultaneously be better for your brakes AND improve your lap times.

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I use bendix CT(ceramic)stealth advanced technology disc pads and slotted rotors to suit.You can use your existing rotors but it is best to upgrade to ceramic compatible rotors.Ceramic pads shed very little dust as opposed to metal content pads so your mags will stay cleaner longer

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