I'm looking for a rear disc conversion and I always see the cross-drilled and slotted brake kits.

Is there a huge difference between

normal kits
vs drilled kits
vs slotted kits
vs drilled and slotted kits?

Just wondering to better help me on my decision for a kit.

thanks

Crossdrilling

Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the 40’s and 50’s, not a whole lot. Rotors were first ‘drilled’ because early brake pad materials gave off gasses when heated to racing temperatures – a process known as ‘gassing out’. These gasses then formed a thin layer between the brake pad face and the rotor, acting as a lubricant and effectively lowering the coefficient of friction. The holes were implemented to give the gasses ‘somewhere to go’. It was an effective solution, but today’s friction materials do not exhibit the same gassing out phenomenon as the early pads.

For this reason, the holes have carried over more as a design feature than a performance feature. Contrary to popular belief they don’t lower temperatures (in fact, by removing weight from the rotor, the temperatures can actually increase a little), they create stress risers allowing the rotor to crack sooner, and make a mess of brake pads – sort of like a cheese grater rubbing against them at every stop. (Want 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.)

The one glaring exception here is in the rare situation where the rotors are so oversized (look at any performance motorcycle or lighter formula car) that the rotors are drilled like Swiss cheese. While the issues of stress risers and brake pad wear are still present, drilling is used to reduce the mass of the parts in spite of these concerns. Remember – nothing comes for free. If these teams switched to non-drilled rotors, they would see lower operating temperatures and longer brake pad life – at the expense of higher weight. It’s all about trade-offs.

Slotting

Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the ‘glazing’ often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)

From:

http://www.teamscr.com/rotors.html

Nice tech articles at:

http://www.teamscr.com/techarticles2.html

We run regular rotors on our road racer and have had no braking problems at all. Pad selection is about the most important choice you have to make.

I can tell you this, I used slotted rotors on the front of my Tahoe and there was less brake dust on the wheels compared to conventional rotors.

Slotted rotors have a slight advantage as they keep the face of the pad fresh by "cutting" a layer off they as they spin.

Drilled rotors have zero advantages other than the "bling" factor and actually will reduce braking capacity by the reduction contact material and reduced cooling capacity.

The cross-drilled vs. slotted vs. standard rotor argument has been thoroughly discussed to death on all tech message boards.

For some engineering POV check out corner-carvers.com and search "cross drilled rotors". Note, typically a NSFW as well as not safe for young children site due to the language, links and posted images, stay out of GD and you will probably be OK (less some creative name calling).

Hey thanks for the information. I'm aware that this topic has probably been argued and beat to death but it hurts the eyes trying to go back in time looking for the topic. I'd just rather ask and hope someone is nice enough to enlighten me. Thanks for all your help!