Got back from Roebling Road this weekend and, while switching back to street pads, noticed the holes in my rotors were clogged with brake dust. I've heard slotted are better, but I have looked on Suncoast and Pelican and don't see any for our cars.

Next time I will make it a point to use compressed air on the rotors before going just to be sure they are clean to start.

 

Since I have been tracking I have changed over to slotted rotors and they work great, and no worries about cracks.

 

Where did you buy them?

 

I think 80% of my car's dirt come from the rotors and pads.

A strong stream of water at every car wash will ensure those holes remain clean. Plus, the squeaks go away.

 

They are made by Sebro which is a good company, I got them from Autohause, but they are available many other places.

 

Check out Girodisc. They have slotted rotors for our car in 350-380mm size. Lighter than OEM as well.

[QUOTE=Don;4201839]Got back from Roebling Road this weekend and, while switching back to street pads, noticed the holes in my rotors were clogged with brake dust. I've heard slotted are better, but I have looked on Suncoast and Pelican and don't see any for our cars.

 

+1 on that

 

FYI, as a comparo (so they say anyway) :




Drilled vs slotted rotors, what is better?



There are many claims as to the benefits of drilled vs slotted rotors on stopping power. This guide is intended to provide some facts about drilled and slotted rotors. As a member of the SAE (Society of Automotive Engineers), I was pleased to see a paper "The Effect of Rotor Crossdrilling on Brake Performance" by two GM engineers published in 2006. They examined three vehicle platforms with cross-drilled rotors vs standard rotors to measure convection cooling capability, fade characteristics, wet braking, pedal feel and lining wear. The result is summarized as follows:

1. For the sports sedan, the coefficient of friction was 21% higher for drilled rotors than standard front rotors at 340F and higher using 15 brake snubs at 62mph. The track simulated 124 mph fade test showed 37% better brake output for drilled rotors. The drilled rotor brake temperature was about 150 degrees cooler.
2. For the performance car, the coefficient of friction was significantly higher for drilled rotors especially at high temperature.
3. Wet braking at high pedal pressure was the same for drilled or standard rotors. Wet braking is not significantly improved by drilled rotors.
4. Pedal force was much more consistent with drilled rotors over the brake temperature range. That is, to stop at the same deceleration rate, the driver does not need to modulate pedal pressure based on different brake temperatures. This reduces driver fatigue and improves brake response.

 

Nice but the report compares cross drilled vs. solid. That's not what the OP asked.
The big problem with cross drilled rotors is that they have the tendency to develop hairline cracks between the holes.

 

Well, the report was titled, "Drilled vs slotted rotors, what is better?" Now I am all confused.




I am fully aware of the hairline cracks, but this has been a non-issue for me. I have always been a fan of drilled rotors. I don't mean to patronize Porsche, but I am sure their engineers all concurred that 'overall' drilled rotors are best for their cars.

 

My bad, no idea what I was seeing on the screen, sorry

 

Hmmmm, how many RACEcars do you really see with drilled rotors. I mean if that's the best for the track, wouldn't all race cars have them?

 

My bad. When I say "overall", I meant everyday use and not racing. I am sure if I were to race, my pads would be different, tires, and rotors too.

 

If you are set on cross drilled rotors for the streets, Girodisc also has them. Lighter and larger to fill out the wheels.

 

On my prior BMW 335i, I used zinc-plated rotors from brakeperformance.com. I'm not sure how they stack up from a heavy-duty racing-worthy point of view but from a sporty on-the-road point of view they did fine. The zinc coating worked great to reduce the rust. Price was reasonable and they are made in the USA. You can choose between drilled, slotted, drilled/slotted, and dimpled/slotted.

Next time I need some Porsche ones I was going to consider these again. There are also other coated rotors out there, I must for me the next time around since I like keeping the wheel barrels clean and having to clear out the rust that gets slung onto the barrels after a through was gets annoying.

Outside of your question, but on the cleanliness thought above, I also have used the Hawk Performance Ceramic pads on both of my 997s and the reduction in dusting was remarkable.... something to consider when doing your brake work. Performance is still fine for me in my on-road sporty driving. Highly recommended.