It's arguable.

Besides, the entire racing community has already established that holes do not increase brake rotor performance. That sums it up for me; if it doesn't offer improvement I don't need to worry about it. It's like debating which side to part your hair on.

...review all the quotes from brake manufacturers I posted earlier in this thread. Real racecars don't use brakes that look cool or are cheap or expensive, they use what works best.

I'm sure some people also still believe the earth is flat, man never went to the moon and that dinosaurs still live in a jungle somewhere. You can't convince those who have made up their minds already

 

Word, I was just wondering and thanks for the info.


The earth is round!! LIES!! LoL =P, btw you forgot to mention Nessie the Lockness monster

 

My first experience with slots, I ground 2.5mm deep about 1.5mm wide into my Audi rotors with a Dremel cutting wheel, 5 slots each face at about 45deg off-radius leaving about 6mm non-grooved at inner and outer rotor surface, with light stone grinding at edges to reduce pad scraping. I got hooked. They worked very well, so I ordered an Autotech sport tuned set in zinc chromate dip. Well, I got these with holes too, but yes, mostly for posing. Slots really perform. Is there a slot-hater among us?

 

I have slotted and x-drilled rotors.

They look great.

I use to have just x-drilled rotors.

The slotting seem to have a slightly better bite.

One thing that I noticed is that the slotted rotors create more brake dust than x-drilled rotors.

I will say that I do notice less brake fade when I'm hard on the brakes.

Also, in the rain, if I were to be so lucky to run into a puddle and get the rotors wet I don't have to pump that brakes to get an immediate braking response.

Just my experience.

 

Wow.. for once I have almost impeccable timing!

I was doing a search for some new rotors that my friend offered me, and I stumbled across this thread somehow. If it had been a really old post I would have been hesitant to reply and bring it back “from the dead”. Since it’s fairly new though, here goes…

From what I read, even though some of you had bad things to say about cross-drilled and slotted rotors (which started to scare me at first), I think they will work out for me. When I comes to cars, I’m a total noob.. what I know is limited to what I’ve worked on, and that isn’t much (which is good thing because that means very little has gone wrong with my car that I’ve had to fix, but a bad thing because there are some things I would like to work on to improve performance but don’t have the funds.. :P). I don’t know the first thing about brakes (though I could rebuild my engine if I had to..!), so I’m hoping you all can confirm that my logic here isn’t all wrong.
I do have a Mazda.. though not an RX-7. I plan to take it to the track to get some stock times, and then once or twice again next year when it is supercharged (please no flames, I know whenever newbies come around throwing around sc/turbo or the dreaded “NOS” related words, that people automatically are suspicious and think they haven’t a clue what they’re talking about.. I do! ) Besides 2 or 3 mild trips to the track, I will pretty much baby my car. I don’t street race, etc. I like to get up to speed, sure, but not in situations where I’m going to have to immediately slam on my brakes afterward. And I rarely go over 80ish, so I’m not too terribly concerned with my stopping power. My stock brakes have suited me just fine; however they are wearing now and it is time for them to be replaced.
Considering this and the fact that I could get some cross-drilled/slotted rotors for less than the cost of whatever rotor Autozone, etc. has to offer me, would anyone recommend that I spend more on regular rotors? I don’t care how my rotors look.. lol.. so that is not a factor.
My other option is to get my rotors refinished, but I don’t know where I would do that or how much it would cost. For me it’s easier to buy a new part and put it on myself than to trust a mechanic to fix something (if I can’t just fix it myself).. lol
Just about everyone I’ve mentioned brakes to says to get cross-drilled/slotted, and this is the first time I’ve heard arguments against them, so I’d like to know if you still think they’d be bad for me.
Thanks in advance for any response!

 

If it's a street driven car and ultimate braking potential is not the goal buy whatever you like. If the brakes are going to be punished often then there are other facts to consider...


www.tirerack.com sells plain Brembo FD fronts for $65 each and rears for $81 each.

 

They won't

And I can get all 4 cross-drilled and slotted rotors brand new from my friend for uner $100.. which should explain why I am most interested in them.

 

just an fyi for ***** and giggles. i e-mailed brembo and they said that they do not cast the rotors with holes in them. it's a big rumor. i was informed that all brembo cross-drilled rotors, are in fact, cross-drilled.

 

I have always heard that cross drilling was to expel water when the disk gets wet. Ever try to brake after driving through a deep puddle?

I've ridden my motorcycle in the rain with a solid front rotor and when that front rotor is wet it is nearly impossible to stop. Cross drilling the rotor is a common upgrade to cure that problem. Lots of motorcycles have cross drilled rotors for this purpose. Look at a motorcross bike with disk brakes.

Most of the above posts quote race cars and race blah. Well Most race cars don't even drive in rain much less a deep puddle. For them I can see how it would be a waste. On the other hand most Rx-7 owners don't drive through deep puddles and the rx-7's disk brakes do have shielding on them so they rarely get wet enough to cause any problems.

I've felt the brakes on my FC (vented front and rear) are exceptional.

Thaniel

 

I have noticed that x-drilled helps in the wet.

 

If it's wet outside you don't need as much brake anyway. If it's wet outside and the rotors get wet then I assume the tires and road are also wet, therefore you have less traction. Since you have less traction it really doesn't make any difference. Once the tires are locked any more brake is pointless.

Motorcycles drill the rotors to reduce mass. A motorcycle is not that heavy and it's rotor is very large for the bike's weight and hung right out into the oncoming air. It can survive even though it's drilled. The center of gravity with a rider on board is much higher than most cars so they can't use all their grip for braking. Adding more brake to a bike would only send the rider over the handlebars at a higher speed The front brake and tire have the potential to brake harder than the bike can accept because of its cg location.

As for racecars driving in the rain the only racers to my knowledge who do not race in the rain are oval track racers; both dirt and asphalt. Everyone else races in the wet unless conditions are torrential.

 

Notice I said "Drive" thorugh a deep puddle. Ever been offroading or driven a car through a flooded road (or down a river). Once back on dry ground hit the brakes. WHOOOOAHHH. For a second they aren't there. Try it. It's kind of freaky.

Even just riding a bike in the rain when it is wet outside (not recommended but sometimes it rains unexpectedly), on a motorcycle, having control of the brakes is critical. Having them not perform as they normally due to water on the rotor only makes things MUCH worse. This is how it might go. Hummm I'm not stopping so I'll put more pressure on the front brake....rotor finally clears all the water off and oops now too much...Someone call an ambulance. The brakes need to be predictable even when the rotors are wet.

Cross drilling is effective for helping to keep the brake pads from hydroplaning on the rotors. Personally I do NOT think it is necessary on an Rx-7. However that doesn't mean that cross drilled rotors don't have merit. There are times when it is appropriate cross drill.

The motor cycle book I read recommending to cross drill the front rotor on my '74 motor cycle was written way before cross drilling was trendy or common. I believe the copywrited sometime in the 70's. I think I may even still have the book. No longer have the motorcycle.

 

Part of ur point makes sense.

BUt if i can get the first good initial bite that may make a difference of a few feet on whether or not I wrinkle my paint and metal then it's worth it.

The ABS can take over the rest......

 

i have slotted rotors and dont hear a thing just confidence, and under hard braking is the sound of well...decelaration

 

My old FC has cross drilled rotors and no dust shields. When I drove it in the rain for a few miles, the water would disable the brakes for a second. Scary!

My CR250 brakes do the same thing when riding in the wet. They would get waterlogged and not work for a second. But many aftermarket companies sell solid rotors for muddy conditions to help reduce the amount of wear from mud and grit.

 

I don't think drilling is ALL about reducing mass in motorcycles. They still have cooling issues and usually warp if overheated. I think the holes are used for cooling by the incoming air. BTW, there are no chamfers on the holes on bike discs.

Most of that time happens on the track with sticky tires, just like the FD's brake system.

 

FWIW, I went to the last ALMS here in Northern California, and upon closer inspection of the GT or GTS ( I forget which class now)racecars, I saw that they were using drilled rotors. They were not drilled in the typical sense, the holes in the rotors resembled moon shaped holes , which would look like this- ( . These rotors were not carbon but steel rotors as far as I could tell.

 

What you saw were not drilled rotors. Drilling makes a hole all the way through the rotor. What you saw were crescent shaped slots in the face, probably similar to the ones in these pics: pic1 pic2

 

mhmm slotted rotors

 

funny how you can tell me what I saw Uh, you are wrong, the moon shaped holes were just that, holes. What makes you think I do not know what cross drilling is???????

 

Are these full moon-shaped holes we're talking about or crescent moon-shaped holes we're talking about? Were there any pink hearts or yellow diamonds?

 

LMAO! classic.

 

P.S. I have slotted and cross drilled rotors. After changing my pads I noticed the one or two of the cross drilled holes are starting to crack. Next set is just going to be slotted. I tend to be fairly hard on my brakes and use very abrasive pads. This could be why they are starting to crack.

 

 

Why are people so stubborn about this?
They are done for weight reduction.
When you're talking about top-tier racing like that, there are restrictions.
Did you confirm with their (brake) engineers about why they brake rotors are designed like that?
Yeah...I thought you didn't...


-Ted