At first one would say better cooling, BUT it is a maybe.I've been looking for brake pads and rotors for a friend, and I see O.E. rotors, and the supposedly "upgrade" ones that have drilled holes and/or slots for only a few bucks more. Are the drilled or slotted rotors really any better?
As brake pad material is vaporized by the heat of intensive spirited driving it produces gasses that have to escape to reduce brake fade. Drilled and/or slotted rotors help to vent those gasses. For a plain Jane daily driver it will be hard to notice a difference. The brakes will feel better simply because new pads and rotors are present. Drilled/slotted can result in slightly shorter pad life because they wipe off pad material faster. That, too, is hard to quantify because so many cars with d/s rotors are driven and braked harder. My pickup warps OEM plain rotors in about 20k miles so I might try d/s because they don’t cost more and pads are a cheap half hour job, just to see what happens. If your friend drives hard and lives in mountain country, why not? For my old man flat land driving I don’t expect to notice better braking other than maybe better warp resistance but I have no proof of that. It is flat here, we can see a mile down the road, and we roll out to a stop and hardly use the brakes.
What makes them fail ? How do they look ?My pickup warps OEM plain rotors in about 20k miles
How would you know? The only effect of warped rotors would be that the caliper slides back and forth on the slide pins alot, but it doesn't affect how the brakes respond. If you're assuming they're warped because the brake pedal goes up and down when you press on the brakes, that's not because the rotors are warped; it's because they have pad material fused to them, making them thicker in some areas than others. If you want to assumed they are warped, go right ahead. Rotors that are actually warped cannot be turned (machined), but those affected by having pad material on them could be. However, for either problem, the easiest, and often the most economical solution is to replace the rotors, anyway.Mine are warped, no doubt about it.
The fact is: The discs were never warped at all. Every warped brake disc that we’ve investigated with the assistance of our suppliers shows uneven patches of friction material from the brake pads on the surface of the disc. These patches cause variation in thickness (run-out) and the vibration under braking. Brake manufacturers have been struggling to deal with this situation for years because warped discs are so readily blamed for brake-related vibrations.