944 Hooligan

if drilled rotors are overkill, why have all modern porsches for at least the last 10 years come with them as standard?

i was in a 95 carrera with drilled oem porsche rotors and when the brakes were hit it felt like the revolution of the planet was going to stop.

Serge944

Because the brakes are so powerful you don't need extra surface area on the rotors. Some say that they have a braking advantage in the rain, but that is very minimal if even existant. Also because they look damn cool...

Once again...pads have a larger impact on braking and initial bite due to their friction coefficients. Brake rotors have smooth surfaces.

RMills944

Z-man,
I was hoping you'd chime in here along with M758 since I know you two have racing experience and know your material. I'll probably just stick with the regular rotors and more metalmasters or pagid pads when I change them up. I'm not looking for anything that drastically cool looking since the 15" cookie cutters hide the rotor anyway, and I'm just trying to see what will stop me best.

Hopefully, I'll get to do more autocrossing since it's not my daily driver and I've got most of the engine work I wanted done last year.

Z-man

Side note: cross-drilled is a misnomer when it comes to Porsche OEM rotors - the holes are actually CAST into the rotor when they pour it!

That said, not ALL recent Porsches come with drilled rotors as standard fare. It is available as an option on some, but solid rotors are often seen on modern p-cars.

The 'gas escape' theory I have heard, as well as the 'wet weather stopping is better since the water can go somewhere.'

Disk warping? I've heard that warping can be an issue with cross-drilled type rotors if a lot of brake pad residue builds up in the holes. Cross-drilled rotors also tend to wear brake pads faster.

Regarding cracking: typically, on rotors, cracks begin on the edges - with cross drilled rotors, you've got a lot more edges on the rotor itself, which allows more opportunities for them to show hairline cracks. It's when the cracks start getting connected to each other on cross-drilled rotors that you have to worry about replacing them. Hopefully, by then, the rotor will also be below thickness spec and will need to be replaced anyway.

While cross-drilled rotors do have some benefits (if you really believe the gas escaping argument), they also have some issues that are inherent with the design.

-Z.

Jakerx

When being interviewed, a representative of Ferrari was asked why the 360 modena street car comes with cross-drilled but various Ferrari race cars come with solid rotors...he simply stated "the cross-drilled rotors look cool and help sell the car."

iloveporsches

I'd believe that. Cross-drilled rotors certainly look cool.

In Formula SAE, we cross-drill our rotors for weight savings, but I don't think that matters as much on a 3000lb car.

GlenL

I've had _slotted_ rotors that cracked heavily. No pieces flying off, though.

Drilled are fun. With really large pads the surface area lost to the holes doesn't matter.

I think that slotted are the best approach technically. The slots help shed water and high-temp gases. The lost surface area is minimal.

One advantage with solid rotors is that they are easily turned. Not sure how much extra metal the stock rotors have over the minimum thickness. Anyone?

I couldn't find slotted for my 944 and went with the holes. Plan to track it and want the extra cooling.

flamingeye

Mine.

Sam Lin

Both slotted and drilled are simply paying more for something that won't last as long. No performance gain whatsoever, it's an appearance mod.

Sam

joseph mitro

wow, impressive photo.

i vote to save your money and get OEM plain rotors and good pads.

in the racing forum they recommended PF 97, pagid orange, Hawk HP or even metalmasters

L8 APEKS

PBR Metalmasters? Are those supposed to be an OK pad?

My ride needs brakes, I'm gonna do everything at once. Not sure what pads to buy.

Serge944

PBR ultimate pads have higher performance, but squeel and dust more. Cost is identical.

L8 APEKS

TY Serge!

DDP

About the rotors "warping". There is no such thing really. It is a build up of molecules on the rotor from a weak pad that couldn't handle the heat. The rotor doesn't actually bend. So don't buy drilled rotors thinking that will solve your "warping" problem. Just run the stock rotor and aftermarket pad, just like everyone has stated.

Curt911

Really? how would you explain the loss in thickness on a warped rotor then?