I always heard that rotors are slotted or drilled to allow gases to escape. Supposidly there is a build up of gas between between the pad and the rotor and that gas forms a thin layer that prevents the pad from making full contact with the rotor. The slots or drilled holes allow that gas to escape under hard braking. It helps to prevent brake fade. Anyways thats what I was told, it seems to make sense to me. I could be wrong but so far it seems pretty logical.

 

Did you read the first couple pages of this thread that include comments from the leading brake technology companies in the world?

 

well seeing that people will buy anything even if it doesnt do something, i should make 25.3and 1/2 " brake kits. Hondas tuners would be on that like white on rice in a snow storm (<-- thanx major payne!)

 

Sorry I did not read the 1st page, my mistake. If I would have I would have seen that theory already covered. Anyway I agree if nothing else they do look better than the non slotted or drilled ones. I really do not believe anyone can say they have not bought anything just because of the looks before for their car. Thanks for the info though it was interesting.

 

Now why should I need to confer with a brake engineer? Someone stated that ALMS cars do not use cross-drilled rotors. When I was there, I saw race cars using them. We are not dicussing WHY they are used, we were dicussing the issue if they were used in ALMS .

 

As a matter of fact I think the racing team was "Lucky Charms Racing". LOL!

BTW its Pink hearts, yellow moons and blue diamonds with their newest addition of purple horseshoes.

 

A few pages back it was noted that Porsche uses rotors with holes in them (whether they are cross-drilled or cast). I'm not 100% sure, but look at their race cars. They use solid rotors...why then would they use rotors with holes in their street cars??? Because, to most avg. Joe's with that much $$, it's a "performance" thing and they don't know any better, but they sure as hell think it looks good.

 

those "holes" you saw on the race cars, are more than likely "dimples" they aren't crsooed drilled, more llike slotted rotors, but they are little dots on the rotors...iono where to find a pic, but i know those rotors exists...

 

dude, I said their RACE cars have SOLID ROTORS...but their STREET cars use drilled rotors or are cast with the holes already in them.

 

regardless. i am so into looks then. cuz i got the ebay brembo cross drilled slotted and i cant complain, everyone always looks and the rotors. since the are visible thru the 17 crome momo sports. again, i am into the looks, i never track my car, so it doesnt matter. i'll always support a company that will make my ride look like the hot lil bitch she is lol

 

Then you didn't understand my my reply.

YOU are CLAIMING that the drilling is due to better brake performance.
I asked YOU to ASK the BRAKE ENGINEER for the REASON why the brake rotors are drilled.
IF they are consistent with YOUR CLAIM, then YOU are CORRECT.
If it is NOT, you are WRONG.

Is there a problem understanding what I am trying to say here?

I mention restriction, cause some race sanctions (look at F1) have restrictions on brake (rotor) size.
Specifically F1, the wheel dimensions are specified in the rule book.
This directly affects brake rotor size, since you can only physically stuff an x" diameter brake rotor in the maximum wheel size.
Now, if the wheel size is sufficiently large, why not go with the largest brake rotor you can fit?
Now, going with large brake rotors also increases unspring weight.
Upsprung weight is BAD.
So run the largest rotor you can fit (gives you superior "moment arm" [I forgot the right term right now] leverage from the brake pad - this allows you finer control of the brake pads on the brake rotor), but drill the rotors as light as you can to decrease unsprung weight in the corners.
WOW, what a concept!
Brake performance is sacrificed for less weight, but since the rotors are oversized, the slight decrease in brake performance is not enough to be significant in this case.
This has NOTHING to do with braking performance.
This has EVERYTHING to do with less weight.

And, if you've ever seen top-tier racing parts, some of these brake rotors have wear grooves or dimples.
There are several slots or dimples which are milled to a specific depth, and these are used are wear guides.
This is especially true for endurancing racing (ala Daytona 24 Hours, which ALMS does), as a quick look at a certain set of slots or dimples will quickly tell you if the brake rotor is in need of replacement.


-Ted

 

Ok, please show me a quote of me saying that drilling is due to better brake performance. I think you are getting your threads mixed up. you need to go back and read where I first posted on this thread. I have never stated once about whether or not drilled rotors were better than plain rotors. Where are you seeing this????

I simply replied to someone stating that ALMS does not use drilled rotors. He claimed they did not. I claim that they did because I saw them on the cars when I watched the race at Infineon Raceway. They were not drilled out holes per say, rather they were half circles, kind of like moon shaped. They were not dimples for I could plainly see daylight through them. The holes were either milled out, or punched. If I had to guess, they were milled on a lathe. I cannot see how you can get so confused about what my point is. Is it that cryptic that you cannot understand?

You asked me if there was a problem understanding you and the answer is yes. The problem is that YOU DO NOT PAY ATTENTION to what I have said in my posts. If you had, you would clearly see that we are talking about two entirely different topics.

 

You're totally right.
I got the quotes all mixed up.
Apologies for the stupid mixup on my part.


-Ted

 

First hand experience... I put cross-drilled Brembo (which were drop-shipped from the factory, btw, so apparently they do drill their own) rotors on my FD with high-performance pads. One day of lapping and they were completely cracked. Spider cracks at every hole, and cracked all the way through in several places. Completely unusable.

So I tried slotted Brembo rotors this past weekend. One day of lapping and they were warped badly, but with no evident cracks.

I replaced them with my OEM '93 rotors (desperation backups) and FINISHED THE WEEKEND with excellent braking and with no further warping or cracking problems!

So I don't know if that means Brembo are crap, or if both cross-drilled and slotted rotors are crap, but I know I will be trying simple OEM replacement rotors at my next event - besides, there is a 1 year replacement warrantee on rotors from most parts stores.

Oh, and my understanding is that Brembo does drill/slot their own rotors and markets them as their "Sports Rotors". They are otherwise identical to their basic rotors.

 

To clear up the ALMS evidence... I travel with the ALMS Series and SPEED World Challenge on field staff as an Official with the SCCA. I do not recall seing any ALMS cars with cross-drilled brakes in my last 5 years with the series. The only holes I believe you'll see in ALMS are round ones around the circumfrence drilled inwards. This is an easy way to identify Carbon rotors which cost $10,000 to $20,000 a set fyi. In World Challenge we have a few cars with cross-drilled rear breaks to the point they are swiss cheese but this is because they are front wheel drive and the bias setting reduces the braking duty on the rears greatly.

I can't think of any well-respected professional or amateur motorsports class/chassis that uses cross-drilled on all four corners if at all. So I figure the engineers have the right conclusion.

Gas-slotted is the most widely accepted HIGH performance brake rotor option.

As for above, just as you have to learn to manage tires in a race or lapping you have to learn how to manage your brakes correctly.

 

Hear! Hear! Maybe they'll believe YOU. They never believe me

 

Overkill says that he saw rotors with crescent moon holes. I haven't seen anything similar that goes all the way through the rotor, but I have seen references to crescent shaped slots. The curve on these slots is tighter than the half-slots that Damon posted. Stasis Engineering sells such rotors, apparently made from Alcon blanks:

http://www.stasisengineering.com/details/rotor.shtml

Sport Compact Car tested a set on an EVO in the September 2004 issue:

http://www.sportcompactcarweb.com/pr...vo/index1.html

I know no one that actually uses these rotors. I also hereby state for the record that I neither endorse, nor disapprove of this product, and my comments should not be construed to contain any positive or negative undertones and/or overtones with respect to the subject matter hereof...

 

Once a CNC machine is involved, you could have purple hearts, orange moons, yellow diamonds, and blue clovers cut into the surface of the rotor if you wanted. Or tiny rotor shapes...

 

Being the poor broke bastard I am, I used to cross drill my rotors on a drill press, and then chamfer them with a burr bit, thinking I was helping myself save money while hill racing on Okinawa, but a JN friend of mine one day come up after I cracked another set, and basically gave me the same spiel about the outgassing, cracking and whatnot. I didn't believe him at the time, so we made a bet. needless to say several bets later I gave up, as his stock rotors (from a different car) always lasted longer on his SA than mine did. after loseing about 30000 in bets (yen fortunately!) I tried the same rotors he had been useing , and several races later, were stil useing them (albeit lathed slightly for finish) thats when I found out he had been useing the SAME set the whole time we were betting, and used the money he saved, (and mine) to buy a new header.

DAMN can you say trippin over your dick! I found out that he had found out basically the same way from one of his friends, and was trying to recoup his money when he approached me for the bet!

honestly this isn't BS true story, 14 years ago, and I ain't drilled no more since then. another note, I have never tried the slotted type due to cost over here.

cheers
Ken

 

so, dare I ask witch way the slots should be directed. \ or / to say you are looking @ the 12 o'clock position of the rotor with the car facing <-. From what I have read I definitly think slotted is better!! and it did take a long time to read threw this thread.

 

It's not really the direction of the slots that are important, but the direction of the cooling vanes inside the rotor. The vanes function as a pump and when the wheel is turning you want the vanes to be pulling air from the center and forcing it out the outside diameter.

 

Are there rotars with small slots? The ones I've seen seem to be exceptionally large concidering there is a small amount of gas build up. I would think that a tiny indent would sufice, while still maintaining a high amount of contact area and minimal stress.

 

The slots are not there to deal with gas, they are there to keep the spent brake pad debris from being trapped between the pad and the rotor as well as slightly increasing friction and helping to prevent the pads from glazing. The slotted rotor essentially makes the pad self cleaning.

 

I'm not so sure about the moon landing thing, you don't think the video of the first moon landing looks staged? It looks like the lunar lander is being reeled up with a fishing pole by someone who used to make UFO films. What about the limited number of pictures available to the public, you always see the same ones. If I went to the moon I'd take at least a couple rolls of film with me. Also there are the pics with the little crosses added after the fact.

There was pretty good motive for faking too, and who would catch it...the American public .

 

someone mentioned that they cracked their x-drilled rotor and warped their slotted rotor racing. would cryo treating a slotted rotor help prevent warpage by a lot?