Well ...I dont know if the slots and holes make the brakes run any cooler, But ,They sure do make the the driver of the car cooler!
I'm talking strictly about the holes. I believe that slots do benefit by whisking away brake media. I also heard that rotors like that cannot be turned. I have no idea if this is true or not...
I didn't read the PHR article, so I cannot comment there. I will say though that the holes are not so much for cooling, but they vent expanding air/gasses that quickly arise from the friction of braking. If the expanding gas has to vent from the sides of the pads, it creates a slight barrier between the pad and rotor that cannot be compressed. As the parts get hotter, the condition worsens. This is called 'Fade'. I didn't read the article, but I doubt very seriously they declared that fade does not exist. The holes vent the gasses that cause fade. So, PHR may very well have found that holes do not cool brakes, or that they didn't notice an improvement in braking on the car they tested... but that doesn't mean a blanket statement that they don't work is warranted. After all, why would so many racing entities and high end auto manufacturers invest in something PHR says doesn't work? Dave
Read the article. PHR addressed it. With modern brake pad materials, the gasses are pretty much no longer an issue. And any brake will fade when pushed beyond its limit. Smaller brakes will fade sooner than bigger brakes. Drum brakes even sooner than that... Cross-drilled rotors are really not meant for street use. They have a tendency to warp sooner, as there is less metal there to absorb heat. That's why almost no production cars come from the factory with drilled rotors...
All I have to go by is real world experience, my 85 honda civic came from the factory with a solid front rotor (non-vented) and drums in the rear. I live in the mountains so I am very hard on brakes. After going through about 4 sets of stock (advance auto/auto zone) rotors I decided to buy one more set and go ahead and cross-drill them and see if it made a difference. I drove for two years (about 30,000 miles/year) after that and never had to replace rotors again. I sold the car recently with those rotors still on them. That tells me, that in my particular situation, the cross-drilling of the rotors helped them to live longer and made the driver very happy. P.S. The only downside was,after I cross drilled the rotors, they seem to eat up brake pads much quicker than when they were not cross drilled. That didn't matter to me because I had lifetime replacement pads.
Question for the guys that installed the drilled/slotted rotors. Did your rotors come with the bearing races installed, and if they did, did you use them, or replace the races? I purchased a set of the rotors, and also bought new bearings and races. I'm wondering if I should use the races that came with the rotors, or use the new races that came with the bearings.
I have had similar experience as my "best buddy" here has. The drilled rotors on my dad's Mustang have about 45,000 on them and will be on there 2 years in November. The front will probably need new brake pads by the end of the year, but the rears still have a good bit of life left in them. This is my dad's daily driver and he drives it VERY hard. The rotors themselves still look like new. Definately not warped or anything...
i used the races that came with the rotors just check and make sure they are...seated"...in the rotor. my rotors still look as good as they did when i put them on...got a few thousand miles and that included the trip to the roundup. ... ...
