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Through all my research I haven't been able to find any good reasons (other than aesthetic preferences) to ever use drilled rotors. Solid rotors offer more surface area but aren't amazing at heat/gas evacuation. Slotted are effective at heat/gas evacuation but eat up brake pads. Vented are really good at heat/gas evacuation but are heavy. And then there's drilled... they're like slotted but worse and also tend to crack along the drilled holes. What's an application where drilled would be preferred? Or do they just exist to look cool?
I've never tried drilled. Or slotted. So I can't comment on real life usage. It seems that practical uses might be in motorsports but based on the results of heat dissipation and longevity, it doesn't seem like there's a huge difference. There's a video by Engineering Explained on YouTube where he tested out the heat levels and maybe stopping distance of drilled vs. blanks. And if I remember correctly, there was practically no difference in either.
For normal driving, go with regular rotors. You're literally taking away the rotor surface for stopping power and stopping distance by going drilled rotors.
Through all my research I haven't been able to find any good reasons (other than aesthetic preferences) to ever use drilled rotors.
On a street car or even DE days at the track, no. Every single one of my daily driver cars have solid discs (other than the Porsche which come with drilled and vented discs) and I buy the OEM ones if they need replacing. I have no issues stopping...even in the rain.
Yes, it is mostly for looks, just as you get people putting on smoked tail-light or headlight lenses so that I can't see them at night. Car drivers are no different than motorcyclists; they love BLING.
other than the Porsche which come with drilled and vented discs
Huh I didn't know they used drilled! I did a quick search on google and found this post from 2009 that shows a niche advantage of drilled in track use.
Drilled rotors have a bunch of advantages and disadvantages. For track use, the holes provide extra leading edges, giving the pads more initial bite. This is great for qualifying (especially in the high speed braking zones, like Turn 1 at Road America), but fewer teams will use them for the actual race. Apparently the GT3 Cup cars are not using them up quickly enough to be deemed an issue by the team manager. Using radius edge chamfers and/or peening the holes will help them last a big longer.
The holes, if the pattern is developed correctly, do provide additional cooling at the upper temperature limits, but it is not dramatic. 50°C at the friction face is about all you can expect.
Still no pros to switching over to drilled for a daily driver though, but that's fine by me! This was more of a quest for knowledge than anything else. I'm happy with my blank rears and blank vented fronts.
For track use that extra ventilation can be critical in helping to keep the brakes from overheating. Even if it is not a lot, it could make the difference between cooked brakes and ones that still work well. On track you want the latter. Drilling or slotting can also slightly reduce unsprung mass which helps with suspension performance. It also reduces rotating mass which can help acceleration and deceleration (think a smaller flywheel). On a street car it is likely never noticeable, on a race motorcycle or purpose built race car it could make a difference. On track, the price of brake pads is generally negligible compared to the other costs (tires, entry fees, etc.), particularly if you have a sponsor providing the pads free or discounted.
For motorcycle track use, you can get rear brake rotors cut so about 80% of the surface area is gone. The rear wheel can be in the air due to weight transfer at max braking so it is useless at that point anyway. A few of the best racers can use the rear brake to steer the motorcycle in slow corners and so run a little more. Some race orgs also don't allow these in some or all of their race classes. Here is an example of a cut rotor. I have a similar one on my SV650 track bike.
For track use that extra ventilation can be critical in helping to keep the brakes from overheating. Even if it is not a lot, it could make the difference between cooked brakes and ones that still work well. On track you want the latter. Drilling or slotting can also slightly reduce unsprung mass which helps with suspension performance. It also reduces rotating mass which can help acceleration and deceleration (think a smaller flywheel). On a street car it is likely never noticeable, on a race motorcycle or purpose built race car it could make a difference. On track, the price of brake pads is generally negligible compared to the other costs (tires, entry fees, etc.), particularly if you have a sponsor providing the pads free or discounted.
For motorcycle track use, you can get rear brake rotors cut so about 80% of the surface area is gone. The rear wheel can be in the air due to weight transfer at max braking so it is useless at that point anyway. A few of the best racers can use the rear brake to steer the motorcycle in slow corners and so run a little more. Some race orgs also don't allow these in some or all of their race classes. Here is an example of a cut rotor. I have a similar one on my SV650 track bike.
It's more for reducing mass, not overheating the brakes. After all, you're not overheating the rotor, you're boiling the fluid. Brake rotors on most competitive race cars are NOT drilled/slotted because it extends the life of the pads during the race (not for cost benefit) and doesn't provide much of a benefit anyway. The holes on the side of a rotor don't vent much heat, definitely not as much as the vanes on the inside of the rotor body. Remember air flows parallel to the surface of the rotor, not perpendicular.
Just in case someone that buys one can take it to the limit on the track. Total overkill for me and 99.9% of the buyers, but that is the way it came from the factory and there was no way I was going to turn down a 3 year old car with only 157 km / 98 miles on it. Upper end cars will have them like Ferrari, Lamborghini, etc.
Lets face it, there are a lot of clowns that think they are fast, but I haven't heard of any that have broken any track records. LOL For street use and beginner DE days, I would not bother.
The theory behind drilled rotors is to allow a pathway for superheated gas, air, and dust to escape the surface of the rotor and pad.
Slotted rotors are the modern day solution and do a lot of the same without significantly weakening the rotor. Their downside is that they aggressively wear away the pad.
I think nowadays people associate cross drilled rotors with high-performance so "serious" sports cars come with them from the factory.
When I had to change my NSX rotors, I went with a cross drilled set just for the aesthetics. I haven't noticed any difference in day to day driving.
That they are and luckily I'll never have to replace them. The original owner ordered them as an option when he ordered the car. I wasn't thrilled at first, but now that I have them, no brake dust. Hey maybe its because I don't brake for the curves. LOL Also, these PCCB last, especially in my case.
Another thing is the Centerlock wheels; totally useless for 99.9% of us but standard equipment on the GTS, Turbo and GT models. On a street car; what was Porsche thinking? But they look cool but also a pain re removal & installation.
That they are and luckily I'll never have to replace them. The original owner ordered them as an option when he ordered the car. I wasn't thrilled at first, but now that I have them, no brake dust. Hey maybe its because I don't brake for the curves. LOL Also, these PCCB last, especially in my case.
Another thing is the Centerlock wheels; totally useless for 99.9% of us but standard equipment on the GTS, Turbo and GT models. On a street car; what was Porsche thinking? But they look cool but also a pain re removal & installation.
But good lord the PCCB rotor + centerlock wheel combo looks fucking fantastic.
The theory behind drilled rotors is to allow a pathway for superheated gas, air, and dust to escape the surface of the rotor and pad.
Slotted rotors are the modern day solution and do a lot of the same without significantly weakening the rotor. Their downside is that they aggressively wear away the pad.
I think nowadays people associate cross drilled rotors with high-performance so "serious" sports cars come with them from the factory.
When I had to change my NSX rotors, I went with a cross drilled set just for the aesthetics. I haven't noticed any difference in day to day driving.
This is fair on cars with calipers large enough for that to be a problem. On a normal street car it won't provide even an iota of value other than causing accelerated pad wear.
This is fair on cars with calipers large enough for that to be a problem. On a normal street car it won't provide even an iota of value other than causing accelerated pad wear.
^ agree! Newer cars are pretty heavy and have to scrub off a lot of energy. HOWEVER, for most drivers, the don't get the brakes hot enough for the additional cooling or weight reduction to matter. Folks that drive like they are in a racecar will certainly see some form of benefit.
A private event in my 4G TL left the brakes red hot and smoking and I could certainly feel the fade after a few runs on the runway. On the city streets it's pretty much impossible to get them that hot unless your brake caliper is stuck.
At the end of the day, slotted rotors or drilled MIGHT give you a tiny bit shorter stopping distance but the real magic is in the pad compound.
^ agree! Newer cars are pretty heavy and have to scrub off a lot of energy. HOWEVER, for most drivers, the don't get the brakes hot enough for the additional cooling or weight reduction to matter. Folks that drive like they are in a racecar will certainly see some form of benefit.
A private event in my 4G TL left the brakes red hot and smoking and I could certainly feel the fade after a few runs on the runway. On the city streets it's pretty much impossible to get them that hot unless your brake caliper is stuck.
At the end of the day, slotted rotors or drilled MIGHT give you a tiny bit shorter stopping distance but the real magic is in the pad compound.
To be clear, drilled/slotted rotors do very little to prevent heat accumulation. They are to vent gasses that build up between the pad and the rotor. For a normal single piston caliper, it doesn't do jack. For an 8 piston caliper, it may make a difference when running HARD. For normal driving, it doesn't make any difference.
Admittedly I am pretty ignorant about PCCBs. One of those out of sight, out of mind things. Kinda, sorta out of my price range
I assume the best use case for them is for somebody who drives their car primarily on the street and takes it on spirited canyon runs? Should be able to handle the heat from that pretty well without getting brake dust on your wheels. My impression was that they lasted forever, at least on cars that didn't see heavy track duty.
Initially I thought the biggest downside to them was cost, but it looks like they also wear faster when you put a ton of heat into them.
Are there any pros to using drilled rotors?
There are a few sites that get into it. Might have been Stop Tech?
