I finally got a chance to install my new rotors, I got them off Ebay for around $240 shipped.

They are drilled & slotted
Brembo fronts & Bradi in the rear

They feel good but I haven't put them to the test yet.

 

those look nice, I am going to go with the 4 brembos rotors that are on ebay right now with just cross drilling. I dont like slotted rotors as they just eat your pads that much quicker and are really meant for high stress applications.

The slots have a sharp edge that actually scraps the pad clean each time giving you a clean surface to use against the rotors but the scraping does considerably shorten the life of the pads. Cross driling just allows more heat dissapation which is the purpose in the first place.

Rotors with both though, like yours, are good cause it wont cause as much wear from the lots when they are also cooled by the drilling.

 

took it to my little test area and damn they put off some brake dust.

there are pics of my little test area in the Fun/Scenic roads forum

 

Padanky, Are they the ones from a seller called "raceconcepts"? I have been looking at those, he has stainless lines but he can only get the front brake pads. I am still waiting to hear back from Mazdaspeedwest about a package price outside of the group buy. I want to do a complete setup and like that they are zinc coated.

 

Yes!
They are really nice.

 

Rider 69, 'raceconcepts' got me all 4 rotors, front AND rear pads, and stainless lines for $330. I was vacationing in CA, and I called Wood, stopped by his shop and picked them up in Santa Ana. Nice guy. If I can find it, I will try to get the part numbers off of the box for the rears so you can refresh Wood's memory. I purchased slotted only Brembos.

 

Hey Padanky just wondering how big are the rotors.

 

OEM size.

 

This is misleading...Any non perfect rotor surface will cause above normal pad wear. Most cross drilled rotors actually cause more pad wear than slotted...A rare few expensive cross drilled rotors are fire polished, which refers to a tedious task of heating the edges of the drilled holes to a rounded almost counter sunk state, which helps with the pad wear...But it also is controversial, unless done perfectly and with the right heat cycles it is said to possibly cause stress points in the rotor surface and makes the rotor weaker overall...which is also said of cross drilled rotors in general...

Slotted rotors have been said to be better for the street becuase they are structurally stronger...I dont' know how true that is, but they are also said to offer the same amount of cooling advantages without the weakness problems...

A rotors ability to cool is directly related to its mass...The smaller the mass of the rotor, the faster it heats and cools...Cross drilled rotors have a smaller mass than most slotted rotors, simply becuase more material is removed from the rotor...but it depends on the manufacturer of the rotor, some have a lot of holes, some don't...

So both slotted and cross drilled rotors will cause faster pad wear...slotted may be stronger according to some...Drilled are better for heat dissapation according to some...But again neither will be as good for pads as the stock rotors...

 

but since you are removing mass from the rotor, it can't absorb as much heat and will rise in temperature more quickly than a solid rotor. as far as heat (fade) resistance, more mass is better. there also is no way that drilling or slotting a rotor will make it stronger...any engineer will tell you that a surface imperfection weakens a structure.

the actual advantage to cross drilling is weight savings. also, modern pads don't need slotting to "clean" them. for the most part, cross-drilled and/or slotted rotors are mainly a cosmetic thing b/c modern brake technology has solved the original problems that these designs were meant to correct.

that said, if you like the look, go for it. it's not really going to hurt anything on a street car.

 

I am impressed...I was trying to only touch on the specific heat capacity of rotor materials to keep it simple...

Honestly I never understood fully how all of this applies to brakes. You are correct about heat absorbtion of a smaller mass rotor. This is only a guess so correct me if I am wrong. Brakes fade mostly after a series of hard stops... The rotor absorbs tons of kinetic engergy which is converted to heat. Once the rotor reaches a heat threshold, burned pad material begins to vaporize, expand and push the pad away from the rotor surface and in turn your brakes suck. Racing teams began using cross drilled rotors years ago to allow those gasses to escape through the rotor surface rather than pushing back on the pad and caliper. The disadadvantage, as you mentioned, was the lower mass of the rotor allowed it to heat quicker, but becuase of the escape route you don't notice it. So the cross drilled rotors may have a higher heat threshold? Also another advantage is the opposite. The lower mass allows the rotor to cool faster, so you don't start a brake cycle with a boiling rotor...So the rotor is less prone to heat soak which is the main threat on standard rotors.

I don't think any "streetable" stop can cause fade to creep in. It needs to be done multiple times. I have hauled down from 150-0mph in a cross drilled equipped M3, with absolutely no fade what so ever. By the time I accelerated back to 150, the lower mass of the rotors allowed them to cool much more than standard rotors. The rotor may have reached higher temperatures, but the holes make your pads not care. This is a bad example, but my point is even though the mass is less, one stop can't induce fade during that stop. And by the time you get back to speed to do it again, the rotor cooled enough to let you do it again. Also this is reffering to "man"ly stopping. If you ride the brakes slowly from 150-0 they would probably melt off.

I made these assumptions with no research, so it could be completely off...I just took some old **** I remembered from chemistry and a memory of squirting around in a M3...

 

the only time i've experienced noticeable fade was following some WRXs on the blue ridge parkway, on a series of downhill twisties, where there was almost no opportunity for the brakes to cool before being used again (hard). slowing down and not using the brakes much for 5 or so minutes made the brakes come back just fine.

i would suspect that the M3's fade resistance came more from the fact that the rotors are huge and the pads and fluid are high-temp resistant. as i said, cross drilling and slotting were answers to problems that don't really exist anymore in high-performance braking systems...today's pads and fluids are able to resist much higher temps.

IIRC, Porsche puts cross-drilled rotors on the 911 Turbo but not the higher-performance GT2...

as far as drilling allowing a path for gases to escape, i'm sure it helps. but as the pad mat'l vaporizes and creates gas, it's happening on every square millimeter of the pad, it doesn't seem that the *relatively* few holes in the rotor are providing much of an escape path. not being a brake engineer, i could be wrong, but the more massive rotor seems like the better answer.

however, if a more massive rotor is not desireable (for example, on a race car), perhaps cross drilling allows use of a less massive rotor.

again, not an issue on street cars, though. the bottom line is that installing cross-drilled rotors on your Protege won't decrease your stopping diatances...better pads (like Hawk HPS) won't help either. the first step would be better tires (and i know the stock brakes can lock up even R-compounds just fine).

 

The M3 does have massive brakes (I think they are almost 14"), but it also weighs a lot more than a Protege...but anyway you are probably right, I never tested the M3 when it had the stock rotors...The E-spec cross-drilled rotors were ordered during the first brake service. But from what I remember it never had a fade problem in the first place...I am not a brake engineer either, and everything I have seen that makes an advantage seems to offer just as much of a disadvantage, mostly becuase I don't understand them very well...

FWIW the ceramic brake rotors are available for the stock 911 turbo (but they are $9000), the GT-2 includes them if equipped with the club sport package (which most are)...But if you custom order a GT-2, you can get the stock turbo brakes and the heavier power seats which decreases the price a few thousand dollars from the GT-2's $186,000 base price...

 

hey jaredspangler have you found the part number yet? I emailed Wood and he told me he had everything but the rear pads. The only rear pads I've been told that exist are OEM and Axxis makes a set too.

 

Sorry, but rotors are cross drilled to release the gasses created during braking, so that the pad actually touches the rotor. A secondary effect, the drilling also helps maintain the integrity of the pad surface, helping ensure that the surface does not glaze. Slotted rotor also release the gasses and scrape the pads, however are generally less likely to stress crack, leading to less maintainance, hence their existance. The vast majority (99%) of the cooling that a rotor (or brake system) recieves is through the venting of the rotor. Look at our front brakes with the wheel off and you will notice that the rotor is like a sandwich (no Forrest Gump jokes please) with a solid portion on each side of a ribbing. If you look to the inside by the cv's, you can see the ribbing as well. Air travels between the ribs, (and on each side of the rotor) creating a great deal of surface area for the metal to transfer the heat to the passing air. Cars with brake ducting, help flow more amounts of air through this area. You'll notice that our rear breaks are solid disks, which are not as easy to cool, but with the amount of breaking they actually provide (10-30%ish), they are adequate.