silver97

Would like opions and experience with drilled and slotted rotors. If you had drilled rotors, did they crack from the drilled holes? Has anyone had any experience with just slotted rotors?

Blown 346

Out of all the drilled rotors or drilled and slotted rotors I have seen they all have cracks in them. I have the slotted rotors and have used them for years on all of my cars without a single problem. There was info on how the drilled rotors cracked. It had something to do with either gases or heat getting stuck in the drilled slots.


I would go with the slotted rotors anyday.

Here's some info


Cross-drilled: Years ago (in the 70's) drilling was used to relive a problem called "outgassing", which was caused by poor brake pad formulations. Since the 80s, better brake pad formulation has eliminated the need for drilled rotors. Contrarty to popular belief cross drilling is actually WORSE for heat handling than a solid rotor. The holes are pointing the wrong direction for cooling. Cooling holes need to be in the radial direction (like the spokes on a wheel), not axial. Some racing rotors are cross drilled for weight savings purposes, but these are known to be less durable than solid rotors. "Street" rotors such as the one shown in the above post are cross-drilled simply becacuse it looks cool. Drilled rotors are also prone to cracking. Note that a REAL drilled rotor (one that is drilled for weight savings) looks nothing like the picture shown by the OP post.


Slotted: Slotted rotors were also developed in the early years of performance disc brakes. The theory was that the groove would scrape the pad surface, reducing glazing. Slotted rotors do not warm up any faster than solid rotors. And furthermore, if they did, they would certainly not dissipate heat better. The claim that they come up to temperature faster yet cool more effectively at the same time is a paradox--whomever wrote that needs to go back to physics class! The slots in a slotted rotor are far too small to have an appereciable effect on surface area or mass, and therefore they have no significant affect on cooling or on weight savings. However, they DO create stress concentrations (areas where cracks can form) on your rotor surface.

Zinc Plating. This is just another fancy name for galvanizing. Sure, you can plate a rotor. However, the first time you brake, the brake pads will scour the plating off the braking surface. You might be able to keep the hub of the rotor from rusting, but you cannot affect the braking area itself.

Point & Shoot

Go with Powerslot rotors - they are the best all around street rotor hands down !!

Independent1

There have been a lot of posts on this subject, especially in the autocross and road racing section. There really is no need to cross-drill the rotors. It weakens them. Some people like slots others don't. The slots are supposed to wipe away glaze on brake pads so that they have better bite.

A lot of the people who run HPDEs (track their cars) buy NAPA rotors without slots or cross-drilling for about $30/each. Since rotors get eaten up on the track it a nice way to keep the cost of tracking the car down.

I bought a set of powerslots not too long ago. Have read good things about them.

Blown 346

I agree, Powerslot is what I use on all my cars.

tblu92

With todays higher quality pads the drilled rotors are really more of a "bling" item that a performance item--Gas bulid up under the pads it not an issue anymore--(from what I've read)--However If you do decide to try them--buy some with a good warranty--Most drilled rotors only have a 90 day warranty--because of the cracking problem-- The better rotors are typically double the cost of the cheapies and carry a full 1 year warrany on cracking--

silver97

Thanks for al the great input! All pretty much say the same thing! Makes my decision alot easier now!