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Drilled/Slotted Rotors

3472 Views 31 Replies 13 Participants Last post by  CloNeGTS
Hi again guys, sorry about my absence but school has been taking its toll. I do pop in now and then to catch up every weekend though ! Anyway, my question is are drilled and slotted rotors better and if so, how ? I couldn't help but notice on the CDN STi at the Toronto international auto show that the rotors were just smooth :( . I think drilled looks better too and I could have sworn I saw them drilled (or is cross drilled the term ?) and I was kinda surprised to see them like this. I could just be imagining things again :oops: . I also noticed that other high performance cars like the Lamborghini also on display had drilled rotors and I think Brembos as well, so why the difference ?

P.S. I have pics of the STi at the show but it's nothing you guys haven't seen already. Large wing, muffler, the BBS wheels, hood scoop, rear badging, a side interior shot, pedals, dash(unlit)/steering wheel/cruise control, headlamps, shifter/DCCD control/mirror controls and our STEREO :wink: . I also have one of the door open showing no frame over the glass, same as the WRX (Have any WRX owners had issues with the seal the glass makes when they close the door ?) All pics were taken with an advantix camera so I have to scan them and upload them if anyone wanted to see em. Just let me know and I'll try to do it one weekend !
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Here's a little history link....


Which you actually pick.....actually shouldn't really matter. One, the Brembos should be amazing all by themselves. The first upgrade would probably be new pads. And even with new pads, you usually don't need anything like slotted or drilled rotors unless you are seriously beating the hell outta the car and you experience brake fade from the heat. This would be real road circuit racing......nothing on the street and certainly not autox.
For what it's worth, I've talked to racers who have had disk failures due to drilling. The disk can crack between the holes and cause major problems. I think that slotting is the way to go. Under extreme, prolonged breaking the pads release gas, and the friction causes heat. The slots give a place for the gas to escape. A decent disk with internal veins should be able to handle the heat without cross-drilling.
Re: Anyone live in MD?

Thanx for the responses and the web link... I'm enlightened now !
I say don't bother, when it comes to c-d or slotted rotor replacements. Drilled rotors ask for trouble, and slotted's benefits are shaky at best. Some say they help with gassing when racing, others just complain of hairline cracks developing.


I say the only thing you need to concern yourself with is MAYBE better pads, but make sure they're not TOO grippy, if you're going to be using this car as a street machine, most of the time. Case-in-point, I got Porterfield R4-S pads for my 2000 Impreza 2.5RS (brakes have OEM-sized rotors, and calipers are OEM) and even though they're Street pads, Porterfield's compound appears to be too aggressive for a guy like me. A phenomenon called "pad transfer" has left a layer of brake pad material on my rotors which isn't eaten off by hard braking (since I don't hard brake very often), and the layer is leading to steering wheel shudder.

About 15 minutes of whaling on my brakes in a parking lot or auto-X I guess will solve this for a while, but.... essentially just do some research and make sure your pads are appropriate. Bad advertising on Porterfield's part, in my case--I thought they were, for me. :(

But I really don't think brake upgrades are going to be necessary on the STi, except for those REALLY obsessed few. :D

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What about HI's allocation??

I installed drilled rotors on My s-2000 honda ,and have them ordered for the sti, would'nt care if they did anything better than the stockers, but one thing is for sure ,they make the car look like its worth 10,000.00 more ,in my opinion anyway, :wink:
Ya know how the veins on the STi's brakes dont quite look like normal veins. this is the first time if seen rotors with this kinda pattern. are they made this way to disturbute the stong points of the rotor and help it keep from warping? (thats the best way i could describe my question :roll: )
See how its kinda diffrent?

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:roll: is that a misprint '' aluminum alloy rotors'' they must mean caliphers??? :oops:
why would that be a misprint? What material do you think they make rotors out of?

We sure aren't going to get carbon discs......
:evil: Hey,i didnt say i expected carbon rotors,most street rotors are cast iron ,and race units are sometimes nodular iron, i asked a simple question so if you think they are going to be aluminum fine ! hope thats what you get, :-?
I didn't realize you could use aluminium for rotors either. All I've know is cast iron. I would think aluminium would be too soft for rotors. Guess not.
The only place I've read about / seen aluminum used as part of the rotors was in the rotor hat/hub (right term?).
Aluminum is about 1/3 the density of Iron, so Alum rotors would substantially reduce the unsprung weight. However, they will wear down faster. If this is true, I hope they are inexpensive because they will need to be replaced regularly.

I have been searching on Subaru's site for any indication that they are aluminum and I don't see any. Therefore, I believe that it was a typo in the brochure and that we will see a standard Iron rotor, but we will have Aluminum Alloy calipers.

I"ve seen aluminum rotors on carts and snowmobiles,you have to break them in with wd 40 and they gall the hell out of the pads, so they have to be cast iron , we will be offering drilled rotors with bolt on hats,{hats are 6061 aluminum -2.8 lbs per rotor target price 699.00 cdn $ ,will post pic in a few weeks when our Sti arrives.
Aluminum rotors have been in development for some time. I don't know of any cars that have such an assembly, but it's Brembo....if someone's figured it out, it would be them.

Who knows.....we'll see what we get.
The main benifit of cross drilling and slotting is a reduction in weight of the rotor. This really only matters if your a wheel-to-wheel road racer, and you need every last advantage you can get.

Veined rotors suck in air from the center of the rotor, and fling it outward with centrifugal force.
Wilwood is working on some Pin mount Aluminum Rotors, but they are not finished posting on the web yet.


I called the company and inquired about the typical applications. A rep said they are for Sprint and Midget use.

As someone has already said, it is Brembo, so we will see.
cross drilling and slotting is first used to dissipate the heat and gasses made by the brake pads. When you compare the weight of drilled vs slotted vs stock, you really aren't removing much material, so weight isn't the big benefit.

Just a note.....read that the 911 GT3 has an $8k option for ceramic rotors. They said the things never fade....unreal.
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