Ok I know crossdrilled rotors have a tendency to warp over time. But does the braking improvement outweigh the risk?

Now I know, I know, I know..(ok I said it) I don't track my car much. But I drive my car hard and many times think my oem brakes just plain suck.
Part of me wants the crossdrilled because they look hot. I know...a bad reason to buy a performance part. Also I do know that if I could afford cast holed rotors those would be best. But who had money for that?

I am contemplating just getting Power slots or going and getting some nice Brembo or Zimmerman crossdrilled and slotted rotors I can get on Ebay cheap.

 

I have another question to add to this thread. Is the brake performance increase from drilled or slotted rotors due solely to better cooling? If not, how does reducing the contact surface improve grip?

 

Drilled rotors are all bad as far as I am concerned. It's not warping but rather cracking that is the problem here. I see a lot of drilled rotors at the track and all of them have cracks.

The holes are not for cooling as much as they are for gas release.

 

I've had cross drilled and slotted brembos on my MINI for over a year and there are no cracks. They are the best!

 

*bump*anyone else have an opinion?

 

Sure, why not:

http://www.corner-carvers.com/altimathread.php.html

 

So Todd, like or dis-like?

 

Both. If you want it, I offer it.

I have no desire to enter into this debate. It's beaten to death on every forum out there. There's enough info in that thread above to keep everyone busy for quite a while...

 

Thanks Todd! All I wanted was a single word answer. Thanks for your input. All these debates get confusing and crazy. Your support for the MINI community is superior!

 

...well all I can say is that if you have an opportunity to go to a DE event or any type of race then just spend some time and look around at the rotors. Find some Porsches that track and see what their drilled rotors look like. The holes will have cracks all around them and even worse the rotors will be very prematurely grooved and gouged along the lines of the holes. Quite ugly.

Most I speak to at the track that have them just shake their head and say, "never again". Just wish I had some photos ...

 

by "cast holed rotors" do U mean 'dimpled' or actual holes still in them

 

Cross-drilling rotors reduces the effective surface area, decreases the coefficient of friction, makes the rotors more prone to thermal shock and cracking.

You are right, they look cool, though.

If you are looking for little more effectiveness or bite to spirited non-track driving, try upgrading your pads and if that doesn't float your boat then switch to slotted rotors.

Onasled is 100% correct regarding the slotted rotors and gassing. When the temperature of your pads exceed their operating temp, they will start to break down or "gas". The slots in the rotors allow the gas to escape.

Increased cooling is achieved by getting more air to the brakes via ducting, etc. If you have the proper ducting in place, then cast drilled rotors will operate cooler than OEM rotors and be less prone to cracking than cross-drilled rotors.

 

yah, but how often do you track your car? Street driving isn't gonna cause huge problems because the heat wont get that high. But they wont handle the extreme uses on tracks or auto-x's

I know someone who has had problems with the EBC rotors after 1 track day, cracks all over. He changed to powerslots.

 

Me too, and the Cryo ones take all my abuse without a shimmy in the vehicle!

Alex

 

I think you have answered my questions

 

A G35 driver got some DBA rotors for his G35 coupe. They are cross drilled and he hasn't had a problem with them cracking. He was worried about cracking from all that he had read about cross drilled. He said the rotors are drilled in steps in order to keep the stress down. Meaning that they start with a smaller bit and work their way up to the desired size. The holes are also staggered from one side to the other since they are 2 piece rotors. Basically when they drill through one side of the rotor, they aren't going to the other side in one shot increasing all the heat in each area.

I think they were pretty pricey though (about $600 for the fronts alone). They did have some cool heat marking paint that changes color as the rotors heat up so you can tell what temp they are at without using a pyrometer (well, at least an idea).

 

Cross drilled here.

No cracking issues as of yet. Car is tracked on occasion.

 

cross drilled, that releases the gas pressure, for daily driving, I do not see any reasons why not. I had them on my GTI for over a year (brembos), no problems what-so-ever.

 

been running drilled for years on differnt cars &bikes.drilled them myself.
counter-sinked the holes. no issues,great looks,no effect on pads,no cracks.
for street use only-ok. do not track them.
doug