DARK CLOUD S4

Does the cross drilled rotors crack? I heard that they do crack alot easier then slotted, is this real or just under extreme usage of brake? I like the crossed drill alot more then slotted but was worried about how much wker it will be.

DZeckhausen

Do you plan to race the car on the track? Or just drive on the street?

Shaka

Call them up and ask if the holes are drilled into the rotors, or cast in when they are made. Most rotors are cast, and some of them have the holes in the mold (ala Porsche rotors, etc).

If StopTech is "drilling" the holes as a secondary operation, I would personally be wary of this, based on my past experiences. However, if the holes are CAST into the unit when the whole rotor ring is cast, you will be fine!

Good luck...

AudiBiTurbo

As a Stoptech distributor, I push people away from the drilled rotors. Slotted offer more performance, and drilled rotors from any manufacturer (including Porsche's cast rotors) can readily crack under heavy track useage. With sensitive pads, you can actually feel the slots in the brake pedal, but they offer the best performance. I've been running slotted stoptechs on my S4 (and putting some on my Z06 Corvette) for 2 years with heavy track useage.

Mark Rosenkrantz
AudiBiTurbo@aol.com

AudiBiTurbo

Shaka, I replied to your personal e-mail to me offline. Thank-you.
Any machining process after casting causes "stress risers" in the material due to machining. These stress points are due to micrscopic tears of material when machined, as well as localized heat-treatment due to induced heat (friction) and the tearing action of the material during machining. Porsche casts it's holes, which definately help, but hard-driven Porsches are FAMOUS for breaking the rotors, the cracks propogating from the cast holes. You'll notice that F1 cars run slotted rotors. The slots also have localized machining stress risers, but they're inconsequential because they don't pass all the way through the rotor. Even Stoptech will tell you that it only offers drilled rotors for "looks."
Slotted rotors offer "wiping" action for not only pad gasses, but also moisture, dirt, etc. The only downside of slotted rotors are that under light to medium braking with a sensitive pad ("agressive" pad), you can feel the slots as a slight vibration. This is normal and doesn't impact the braking performance. In fact, I have run slotted rotors on my personal S4 for almost 2 years and love them. I've used Axxis Ultimate, Pagid Orange, Pagid Blue, Hawk HPS, and Stoptech "Red" (similar to Pagid Orange, but a Kerr Friction compound). I've tried these all since I'm a distributor and wanted some personal experience. I enjoy the Axxis Ultimates and slightly higher-temp Hawk HPS for the Street and some track use. For *really* late braking at high speeds on R-compound tires, I've been using Stoptech Red. Similar performance to Pagid, but much less expensive. Of course, one of my mail selling points with Stoptech is the availability of Friction from anywhere. Porsche 993 (last generation 911) front pad sizing. I'm also a Quattro Club (ACCA) instuctor.
Please let me know if you have any questions.
Mark