robbys rex

they both must have thier advantages but what is it? or is it just what one you like the looks of?

DavidDeco

Well obviously you should do a SEARCH but why
choose one?

You can get Slotted AND Cross Drilled. I have them. Brembro and probably others make them and they are not that expensive.

From what posts on this board have said and some specialty shops I've talked to they usually say this:

(a) Cross drilled look cooler
(b) Slotted are better

But you can have both so why trade off?

robbys rex

yeah i love the look of cross drilled but the ones that have both come dimpled. dont really like the looks of that

DavidDeco

Well then I guess it comes down to what you want. The stock braking system is great to begin with so ask yourself this:

(1) Are you racing or in situations where Fade is really a big issue? Then consider Slotted as that seems to be what people advocate for performance.

(2) Do you want a basic street upgrade that also looks cool? Then choose cross drilled. It definitley looks cooler and its an upgrade.

I don't know the trade offs precisely, just relaying.

If you are like me and want an upgrade to a street package get Slotted/Cross drilled, since you don't like that look (and you don't), get Cross Drilled. If you want it solely for performacnce, consider slotted and do some more research on the issue.

Trexthe3rd

Correction, Brembo does not make slotted or x-drilled rotors for the FD. Some people purchase their rotors and machine them before selling. Because they only make regular rotors for the FD, they will not warrant any modified rotors bearing their name. This was discussed quite a while back.
The main purpose of using x-drilled / slotted rotors is to prevent brake fading. A common occurance in track racing where hard braking happend at every turn. So unless you are racing with your car, you will basically never have the 'need' for modified rotors. That being said, most people just get the for the looks.
The second reason is to reduce the weight of the rotors without compromising the structural integraty.
Which is better? That depends on who you ask. It's a never ending debate.

robbys rex

yeah im probably going to go with just crossdrilled since ive never really had any problems with brake fade so thanks for you help so with yours do you have it actually drilled through or is it dimpled i think the older ones were holes instead of dimples

DavidDeco

****, thanks for that info. I have Brembro rotors, definitley new I bought, and they are slotted and cross drilled. They look very very nice and if not from Brembro, who did them did a very professional (looking) job.

Are you sure mine were then modified after?

DavidDeco

Mine have true holes, not dimples. The slots are "dimpled" but not the holes.

Trexthe3rd

x-drilled rotors are all drilled through. Never heard of dimpled rotors??
A side note. The x-drilling / slotted geometry has to be done correctly to compensate for the thermo expansion during the extreme heat cycles. Putting dimples on the rotor would actually cause the rotor to warp prematurely because of the defference in the expansion rate on the two sides of the rotor. Not sure why anyone would want to do that??

robbys rex

im not 100% sure on this but if you look at the rx7store site and look at the brembo slotted/crossdrilled rotors it says that the older ones were drilled and the newer ones are dimpled maybe yours arent brembos or something im not really sure and it also says that they were haveing problems with the crossdrilling would crack and the new dimple style doesnt im not speaking from experience trexthe3rd so dont quote me but it is what the rx7 store is saying

DavidDeco

Well, mine have Brembro on them and the box and they look pretty damn authentic. I'm not going to say they weren't modified thereafter, but whoever did so did a great job. I think at the least, they were Brembro's to begin with.

They are cross drilled through the rotor though. The slots are indentions though not all the way through. I really wouldn't know better because I've had the same rotors for 8 years until last week. They look very nice.

DavidDeco

Damn, I've either watched Yoda too much or I've had enough tonight. Good night you have

robbys rex

im not doubting you guys im just goin off of what the rx7 store is selling so im not really saying thats all that brembo sells i have no idea but as long as your happy with it thats all that matters, right?

DavidDeco

Right you are

BlackR1

Actually, both are good. Brembo sells x drilled with slotting and they are known to crack during a super hard run...BUT... if you cryo treat the cross drilled rotors before installing them... they'll last a very very long time without any worry of warping or cracking. I believe Max Cooper cryo treated his x drilled slotted brembo rotors and they've held up after many track events.

Kahren

iTrader: (13)

ok, you guys need to do a LOT more research, and NOT on the forum but peopel who know what they are doing. ahem. anyway crossdrilled and sloted rotors are worse then stock rotors that come out of mazda, reasons being they have less mass and will overheat a lot faster then the stock rotors. you will say "but what abou tthe holes, that increases teh surface are and lets air get all aroudn them." in this case having more mass is better because the tim ewhen a rotor starts to warp is when it can no longer hold any more heat and dispense of it properly. slotted are teh same thing except they are not as bad as cross drilled. people think thye get the gasses out easier when the brakes are applied. with most conventional pads there are almos tno gassses that form, and the slots on the pads themselves will do that. now u can UPGRADE to a bigger rotor and caliper and have it slotted or cross drilled and then have PROPER cooling ducts made which will cool it down a lot faster then the conventinal rotor. since the mass is now greater it takes a lot longer to get to that point where u are gonna get brake fade, so there is no chance of doing it with BIGGER rotors, and they will cool down a lot faster and before u have to slow down again they will be cold. so to say the least is do not get slotted or crossdrilled rotors. if u want somethign that STOPS well DOESNT fade and cost a LOT less then upgradign to bigger rotors and calipers for thousands of dollars instead buy new stock rotors, send them out to get cryogenically treated (they will last up to 3 times longer this way) and just get some hawk pads. you will be a lot happier

Trexthe3rd

O.K. here is the story. A while back, before Brembo actually produced any of the x-drilled or slotted rotors for the FD (they only made plain rotors at the time). Someone took them and did the machine work to produce a 'Brembo' x-drilled/slotted rotors, and sold them on e-bay for 75.00 a piece. They are in fact Brembo rotors, but Brembo did not do the machine work on them.
Not sure when Brembo started manufacturing the x-drilled, slotted, and slotted/dimpled rotors, it must not have been that long. The slotted and x-drilled configuration is still not available from Brembo.
Looking at the picture of the rotors I have to wonder if they didn't go overboard on the weight reduction for the x-drilled rotors and lost durability?
Again, I don't believe many of us would ever see the day where brake fading becomes an issue, so it's just a cosmetic touch up.

DavidDeco

Makes sense, probably what I got. But they look good!

Let's face it, a lot of us non track racers want an upgrade that looks cool. That why I got it. Despite the diatribe above (not from you but the scorn on mods to a rotor) , I doubt cross drilling or slotting is that inferior, although I couldn't feel it if it was. I'm pretty sure there wouldn't be as much of a market for them for so long if it was truly that inferior. Sure big brakes are better, but I'm not going to give in that cross drilled and slotted are both a waste. If for nothing more my current rotors look better and brake the same. Time will tell if they warp easier and that is worth it. I'm a bit skeptical for my application.

So I'm happy to buy my altered Brembro's that are cross drilled and slotted dimpled. They look great, they brake the same from what I can tell, and that's good enough for me for my purposes.

I'll let you know in a year if they're warped. I'm betting no.

maxcooper

Unless you are on a track, you will probably be fine with whatever rotors you get. Drilled, slotted, both... are all fine for the street, strip, and probably AutoX, too.

But, if you take the car to a track, drilled have proved themselves more likely to crack. I've seen at least one forum member crack up a set of drilled rotors in one day at Laguna Seca. The stock rotors are too small for heavy track use as it is, and the holes give them a good place to crack. Slotted are supposed to be more resistant to cracking, and they increase braking consistency because they keep the pad surface clean. They also heat up the pads faster, which is nice for road racing with track pads. Drilled are supposed to run cooler, but I don't know if that is true for all applications. I just read about EBC's rotors and how they stopped drilling all the way through (or perhaps decided against it from the start) because the cooling effect doesn't work with straight-vaned rotors like the stock ones. EBC uses dimples instead of holes in their rotors.

Obviously Porsche knows what they are doing with brakes and they often have drilled rotors. But, they may actually use rotors with the holes cast-in (and thus less likely to crack because the holes are not as stressed), they might have curved cooling vanes, and they also have bigger rotors that perhaps have enough mass to spare the loss from the holes. Not all drilled rotors are overly crack-prone, but the RX-7 rotors do seem to crack when they are drilled and used on a track.

OEM-style, solid-faced rotors can crack, too. I've cracked up a few sets. The last set of stock rotors I used were solid-faced Brembos that I had cryo treated. This seemed to help them, as they lasted much longer than my previous two sets of the same rotors.

So, choose street (or drag, etc.) rotors based on your aesthetic preferences. If you are going to road race, I suggest solid-face rotors with cryo treatment. When you get sick of killing rotors and want more consistent braking performance, get a 4-wheel big brake kit, as just doing the front throws the balance off. M2, Brembo, and others make 4-wheel kits, or get a front kit and do Mazda RZ rotors from Mazdaspeed Motorsports Development with Widefoot brackets & Wilwood NDL 4-piston calipers (and lines and pads) from Essex. The rear
setup costs about $800-900, but you lose the parking brake function.

-Max

Kahren

iTrader: (13)

porsche actully uses them becaues ferrari uses them and they didn twanna LOOK inferior, they actually wrote this saying that flat fasced are better.

maxcooper

The Ferarri/Porsche thing is funny. I would love to read their comment if you have a link or something.

-Max

rotary-tt

I'm not so sure that any of the upgraded aftermarket rotors (stock sized) are really an upgrade. The stock Mazda rotors have special split internal veins for improved cooling and reduced weight. Slotted and cross-drilled rotors can be a real bitch finding someone to turn them if they get warped. No matter what way you go, if you use the stock brakes hard on the street, get them cryo'd so they last longer.

M.Piedlourde

You have proof of this? I'd like to see it. I find it hard to believe that Porsche puts cross-drilled rotors on their cars just because "Ferrari uses them", and I find it even harder to believe that Porsche openly admitted that they feel the cross-drilled brakes are inferior.

DamonB

Oh good. Max was here so I can hold my wad

Long story short: for the street do whatever the hell you want. For the track stick with a solid or possibly a slotted rotor. Why we need holes/dimples AND slots is beyond me. Guess that makes you double-cool.

Coulthard Fan

Here is a good article on brakes from Grassroots Motorsports that someone posted a while back.

http://www.mr2sc.com/websites/articl...riction_s.html

The bottom of page 3 is most relevant to this discussion.