Here's the deal.

I am upgrading my 04 2.5RS front brakes to the larger WRX. At this point I plan on getting cross-drilled / slotted rotors for the front since they are not much more money compared to the OEM solid rotors.

Now I really like the look of the cross-drilled rotors and know that there are some benefits to using them on the front brakes since they handle much of the vehicle braking. BUT I am not sure if I want to shell out the extra cash on the rears aside from the balanced look with the fronts.

Keep in mind that this is a daily driver (in heavy NYC traffic) that does an Auto-X every now-and-then.

Thanks for any help.
Neil

 

Yeah they look the ****!

(same pic that you saw on my thread)

This is very debated.
There are a couple of reasions that cross drilleds were orritionaly used.
-The holes allow gas created from the brake pad to escape, where as on flats it remains trapped under the pad.
-The holes helped initial bit in on wet conditions.
-In theory through syphon they improve venting. Same theory as blowing across the top of a straw. The syphon created will draw the fluid up through the straw and out of the top of it. The rotation of the rotor will *in theory* do the same thing.

Now why its debated.
-Pads barly gass at all because the compounds have improved so much.
-I have not seen a good argument for why they dont help initial wet condition bite.
-People clame that the holes in fact vent the air out of the 'vains' in the center of the non-solid rotor keeping the air from traveling all the way to the outside of the rotor.

People also will tell you that the holes create more places for cracks to propagate.
This argument is crap because its only under very high heat conditions that this happens, so unless your racing your car professionally you will never see this.

They will also tell you that they will chew up your pads.
I have run them before for 30+k miles on firebirds and never noticed this.

If you like how they look go with them, you will not notice any ill effects and you prolly wont notice much of an improvement; but they will cost you abit extra.

I personally I love the looks and will swear to this day that they do help inital bite on wet conditions and do help cooling, though I dont have any solid evidence of this just think the theory is sound.

 

I don't know, our Boxster S has them stock, front and rear. Porsches has some of the best brakes in the biz.

I have to admit I think they look good and from what I've read as long as you don't overheat them they should still be durable.

On my old Integra, I did x-drilled in front and slotted in back.

 

I have tried that point in debate and they always point out that you never see them used in professional race applacations..
I personally dont put that much stock in it.
The road (daily driver) is totaly diffrent from the track (dedicated race car).

 

There is a big difference between a Porsche and my little Impreza wagon. I would guess 1200lbs and 300+ HP of a difference. But I do get the concept that they use them on most if their vehicles - there has to be a good reason.

I have heard a lot about the higher chances of the rotors cracking. Although I do not do a lot of hard braking, I do a lot of stop and barely go traffic here in NYC. Would this type of braking lead to excessive wear?

 

No doubt your pads will wear faster with cross drilleds but it will only be on the order of 1/32 less life than with flat rotors (if that).
You won’t notice any rotor cracking.
What they worry about is nucleation points for cracks to start. The drilled and also the slotted rotors have more points for this to happen.
The cracks start from superheating the material and cooling, this messes with the grain structure and causes the material to get brittle and cracks start.

Now what I mean by super heating is getting them rotors glowing red hot.
Your daily driving, even stop and go, should never get the rotors that hot so its basically a non issue.
Even if you track your car regularly you wont get any where near the abuse it would take to get them to crack.

 

I think... from what I've read (who knows who is right though) that good drilled/slotted rotors aren't going to crack for most people. I think you really have to heat up the rotors to get them to crack. Now if you take a crappy rotor and drill holes in it, of course it'd be more likely to crack.

Yes, you don't see drilled rotors on race cars, but this is not for a race car. It's for a street car... and looks count

I can't see QUALITY drilled rotors hurting your stopping performance, but at drilled rotor probably won't help either.

I believe brakes wear a bit more quickly with holes or slots because it scrapes a little bit of the pad material away each time it goes by the pad. This is the theory. I'm no brake expert though. I'd bet if you asked 10 brake experts, you'd have 10 different answers.

 

Yep,
This is one of those things that I apply the learn by doing method to.
Chances are if something is very debated there is an element of truth to either side.
At that point I do what I want to,
deal with any consequences,
and make sure what ever I do I never make the same mistake twice.

 

http://stoptech.com/tech_info/wp_bra...lections.shtml

Of course, if the drilled 'racing look' is your preference, you will probably be fine with drilled rotors for street use. I bought slotted replacements for my WRX.

If drilled rotors are not as durable as slotted rotors for performance use than why do many companies still offer both? Simple, drilled rotors are popular because they look like a race part, much the same reason why people buy an aftermarket BOV for an otherwise stock WRX. No performance gain, just bling.

--
0==WW==0
"…axles of evil…" - george w. bush

 

Hey everyone,

Thanks for all of the information. I have been swayed to go with "bling" factor all around and get the front a rear rotors. I got a smoking deal on a set of Brembo rotors (cross-drilled and slotted). I really like the look and really want that look to flow from the front to the back.