Advantages to slotted or drilled rotors? I don't think so.
 

Hi, first post on this forum. I have an 09 Nissan 370z Touring with the Sport package. I have no complaints about the brake package, I think the 14' rotors and 4 piston calipers are more than adequate for even the heaviest street use. From what I've read though, I wouldn't use them for the track without at least swapping out the stock pads for a set of track pads.

I recently had to swap out all four rotors for my 2003 G35 and did quite a bit of research and consultation because initially I was going to just buy Powerslot slotted rotors. There's a lot of misconceptions out there about how slotted rotors deglaze your pads, about how they have better initial bite and how they vent gases and thereby prevent your pads from hydroplaning from your rotors. I think it's all ********. Even worse than slotted are cross-drilled brake rotors. Although a lot of performance car manufacturers use them, it's mostly in response to a perceived consumer demand. Cross drilling does not improve ventilation because the internal vanes are already responsible for radiating heat and because cross drilling reduces the mass available to act as a heat sink and thereby increases the overall temperature of the rotor. Not to mention the fact that cross drilling creates stress points where uneven expansion and contraction can cause hairline fractures. The entire rationale behind slotted and cross drilled brakes is to vent gases produced as a byproduct of the pads compressing the rotors. Not cooling or reducing unsprung weight or deglazing the pad.

First, modern brake pads, to include ceramics, composites, semi-metallics and metallics are formulated to produce very little or no gases. Same with the issue of glazing. This fact in and of itself destroys the justification for slotted/cross drilled rotors.

Second, if you want to improve braking performance, look to replacing your pads, brake lines, brake fluid and tires. I think these changes will have a much greater impact on producing consistently strong braking that investing in slotted or cross drilled rotors.

Any thoughts on this? By the way I ended up getting Kiriu OEM rotors and Hawk HPS pads for my G35. I think the same principles apply to my 370z and I'll be replacing my stock Akebono pads with Hawks depending on how they do on my G35.

I read this post a few times and thought about it for a day or so. First off let me say that I can tell that you have put a lot of thought into the cross drilled slotted rotor topic and that I have no desire to start a rotor war. I have on past cars run both. I can honestly say that on my 92 Corvette that when I swapped out my stock 13 and 12 inch (big in the day) rotors for cross drilled that there was a measurable difference in both pedal feel and performance. They brought me down from 125mph to 35mph many times without bluing or cracking. I have seen cross-drilled rotors crack. I just have not have them crack on any of my cars. My first set went on with new stock pads and stock lines. You can definitely feel the initial bite when you get on the brake. After going to Ferodo pads (do they still make those?) and Russell lines performance was even better.
I've also run slotted rotors. I might run those on the Z. I haven't gotten that far into my build plans yet.

All I know for sure is that we'll never push the car harder enough on the street to need a BBK. The stock sport brakes are more than adequate for this.

That being said, I love the look of a nice BBK on a car. It just looks SEXY!


Thats some good info you posted Acepro, I'd like to see what other information some of the track guys post up.

I feel that the OP's post is not based on any real reasearch or personal experience - just a buch of well thought out dribble.

Using my G35 as a test bed for possible upgrades to my Z, I noticed that with the Hawk HPS pads that I'm getting superior braking performance versus the stock Akebonos. I have an engineering background so it annoys me when brake manufacturers try to ******** about dubious benefits of whatever products they're selling.
I have the Sport package for my 370Z and the brakes are very powerful. In fact, in one of the comparos (can't remember if it's C&D or MT), the 370Z stopped in 103 ft which is the same as the 2007 Porsche 911 Turbo. Now granted, one-time stopping distance is a function of tire grip and curb weight, not necessarily the efficiency of your brake system. My first planned upgrades for my 370Z are to swap out the brake fluid with Brembo high-temp fluid and maybe the pads because of the widely-reported rotor scoring issues. Anyone try these upgrades and have any results to report?

I totally agree with Hawk pads being a good first place to start if you are doing a simple brake upgrade. And like I said up there ^ much of what you say is good information. But you didn't personally test anything but standard style rotors, Hawk pads, and high temp fluid on your G. And magazine test articles are well, magazines. Road and Track tested the 370z base from 70mph n 161 feet. Then they recorded 163 feet from 70 with the sport brakes. We would still rather have the bigger brake package from the sport right? I think the thing is. I find it very difficult to accept the statement that there are no benefits to slotted or drilled rotors. I believe it's more of a cost to consumer issue for most manufactures. And okay, the aftermarket being what it is there is a Ton of hype on brake rotors. But still.
I'm just saying.

And this is where a lot of people who start this debate seem to base their information - I have been on countless car forums where this disscussion/debate starts and none of them seem to come from any real test or personal experience, just the few people who complain of cracked drilled rotors that they bought from ebay.

I run HP+ pads on my C6 with Z06 multi piston calipers, and cracked the rotors with medium track use. I now run slotted dba rotors. If there was a true benefit to cross drilled, would the corvette cross drilled rotors truly be non directional? One side of the car goes the right way and the other the wrong way , as they only have front and back rotors, not left and right. Holes just look cool.

That's the first thing I noticed when I put the drilled rotors on my '93 (Corvette back in '93). I then ran Baer rotors on my '96 and they were 4-location specific/directional. Doesn't the C6 Z06 4 different rotors? And yeah, they kinda look pretty. :tiphat:
Oh, and I ended up running Slotted rotors with my last Brake Mod.

Wait a minute! I know you! C Pilot from the Corvette Forum yes? How ya doin? I'll definitely be sending some stuff to you for coating. The Z is a new project for me. I haven't done an import since my '79 Rx7 days. HAHA. The Z is my sons fault :)

I personally run cross drilled and slotted rotors and a couple of buddys of mine that road race, and the thing i notice from running solid rotors compared to slotted and drilled ones is that brake fade comes and goes faster when they are drilled and slotted since there is more surface area too cool off the rotor so the brakes are effective longer and become responsive again in a shorter cool down time.

Theres nothing worse than trying to mash on your brakes and theres no stopping power. Just my 2 cents.

-Steven @ Amplified

With the right pads (not OEM), you will almost never have brake fade. Back in '93 (16 long years ago), this may have not been the case... Brake pad compounds have come a long way and easily operate at very high temperatures. Modern track pads don't glaze, gass, and for that matter don't fade as long as you don't exceed their design temperature. In my opinion, and I believe this to be very close to the scientific truth, there is absolutely no reason to have slotted or drilled rotors. Slots and holes cause many issues. They reduce mass and this resultantly reduces thermal compacitance; although they may cool slightly faster, they will also get hotter faster than solid rotors of equal size. The slots cause your pads to wear faster with no appreciatiable grip benefit and the holes cause stress concentrations which cause your rotors to crack if they get too hot.

Do the research, get the right pad (carbotechs seem to work great), and solid rotors are the most robust solution.

Just my 2 cents...

This won't happen with the right pad on solid rotors. The sport package solid rotors are properly sized for extended track use.

You clearly haven't been to the track in your Z on the stock pads/rotors haha.

We are all experiencing terrible issues with braking with the stock setup.

I can definitely tell the difference on a motorcycle.

I raced a few times on my stock rotors on my 07 R6, and then got Galfer wave rotors (here's a pic from my bike)

The difference was after the first couple laps, I would have to press the front brake very hard and get little response with the stock rotors, It took an additional 30 to 50 feet to come to the same slower speed, as apposed to the wave rotors. I would race 20 minute sessions on the wave rotors and not one time have to slow down earlier to make up for the lack of stopping ability.

granted its not scientific proof, but i know it does work. I dont have proof, but hopefully this will help you make up your mind.

You will not find a single production-car with cross-drilled rotors with both the left and right side holes going the "right way." Mercedes, Ferrari, Lamborghini, etc. (besides...most brakes on high-end cars are sourced from the same manufacturers), all use the same exact rotor for the right and left side. It does not make any sense economically to manufacture two different rotors.

That said...cross-drilled rotors provide no added benefit over standard rotors. If anything, they give you less surface-area for the pad to contact as well as less mass to dissipate heat, as mentioned above. There is a perception of higher performance with drilled rotors vs. conventional, but that's all it is. Properly slots provide more benefits over holes.

Although this is admittedly a weak argument, take a look at any race-car's brake setup or the high-end BBKs for cars (not just the pretty ones for people who want to look cool). I can promise you that you won't find drilled rotors.

Just curious, but do the holes make a difference on ceramics? Why would Porsche use a cross drilled setup on the 911 GT2?

http://www.gizmag.com/pictures/galle...10755016_9.jpg

The difference, per se, is no different if it's a ceramic or non-ceramic rotor. In other words...the holes are equally as useless in both applications.

Because that's what Brembo supplied them with. As well as Ferrari, Aston Martin, Bugatti, Lamborghini, Chevrolet, Bentley, Pagani, Mercedes-Benz, etc.

^^ besides the theory of hype, your, and the OP's, suggestions of that they are useless doesn't go anywhere.

you are both saying that no proof of benefits = hype, well then show us proof that it doesn't work and its function is hype. the burden of proof is on you and you have not delivered.

I can name half a dozen reasons why its better to have cross drilled, just as you can name half a dozen reasons why its better not to have them, so dont bother with that - go for the testing thats been done and show the results.

-edit- wanted to mention, a well known fact of drilled or slotted rotors is the holes allow the gases and dirt to pass through the hole, versus piling up between the pad and the rotor acting like ball bearings, this allows a much better "bite". I wanted to point this out because you said it gives less grip due to less surface area. The same goes with heating, less mass for heat dissipation? where's the heat going to go if there's no air/gas moving through transfering the heat? thats where the holes come into play - more air movement = less heat. You dont need rotors to prove that, look at any part that creates heat and how it removes the heat.

LOL.

I'll quote GRM:

"Crossdrilling your rotors might look neat, but what is it really doing for you? Well, unless your car is using brake pads from the '40s and 50s, not a whole lot. Rotors were first drilled because early brake pad materials gave off gasses when heated to racing temperatures, a process known as "gassing out." ...It was an effective solution, but today's friction materials do not exhibit the some gassing out phenomenon as the early pads. Contrary to popular belief, they don't lower temperatures. (In fact, by removing weight from the rotor, they can actually cause temperatures to increase a little.) These holes create stress risers that allow the rotor to crack sooner, and make a mess of brake pads--sort of like a cheese grater rubbing against them at every stop. Want more evidence? Look at NASCAR or F1. You would think that if drilling holes in the rotor was the hot ticket, these teams would be doing it...Slotting rotors, on the other hand, might be a consideration if your sanctioning body allows for it. Cutting thin slots across the face of the rotor can actually help to clean the face of the brake pads over time, helping to reduce the glazing often found during high-speed use which can lower the coefficient of friction. While there may still be a small concern over creating stress risers in the face of the rotor, if the slots are shallow and cut properly, the trade-off appears to be worth the risk. (Have you looked at a NASCAR rotor lately?)"

Please read, mainly the entire first post if anything. Some good info.

The real deal about cross-drilled and Slotted Rotors - IWSTI.com: Subaru WRX STI Forums

After that, dig around on the websites of manufacturers of brakes and see what they have to say about drilled vs. slotted rotors. Remember, it's in their financial interest not to talk down on essentially half their products, but there comes a point where you just cannot lie. When you're done doing that, take a peek behind the wheels of a Formula 1 or Le Mans car.

Do I speak from first-hand experience as to which one is better? No. All the cars I have driven on a track competitively or in HPDEs have had conventional and/or slotted rotors so I cannot compare. Does that make my opinion moot, though? Hardly. Doing so would be along the lines of dismissing someone's opinion that an eBay electronic supercharger or "Tornado" does not provide gains simply because they haven’t tried it.

And for the record, the burden-of-proof always lies on the party making the claim of an advantageous development or idea, not the inverse. Now show me a manufacturer, racing-team, or seasoned road-racing enthusiast who has come out in favor of drilled rotors.

NASCAR does use slotted rotors as well as a lot of the GT cars, DP cars, and a ton of other classes/series which I think the above post makes mention of the cars in NASCAR.

I guess what I'm saying is the that the better argument is wether or not drilled rotors have any use since slotted rotors seem to have already proven their usefulness. Also most teams running carbon-carbon set ups don't use any slots.

why the "LOL"?

anyhow, looked into it, I think got me. :tup:

They were useful when asbestos pads were still made. Besides that who cares. If you have the money and you can afford them, get em, they look cool as hell.

I am wondering if AP- Chris and/or Gary could weigh in on this, as it's something I have always wondered. A friend of mine from Wilwood said that cross drilled rotors are a bad idea for anyone except a racing team, where they really need the weight savings and can afford to replace rotors after every race.

It certainly seems true that low-end cross drilled rotors crack. That said, top-line Porsches (GT3, etc.) and others have cross drilled brakes and they seem to do okay at the track.

Can you guys settle this once and for all? Looks aside, when does it make sense to go cross drilled, if ever?

All rotors crack under track conditions eventually, especially if there is insufficient cooling to rotor. You have to look for the tell tale signs around the edge of the rotors to see the beginnings of cracks starting. I've seen non-slotted rotors crack all the way through where someone ignored those signs. The issue with cross-drilled is that the crack tends to play "connect the dots" and can turn from a minor check to a major crack fairly quickly, the stock Corvette Z06 has this issue.

You are correct that many race teams use them for the added bite, but they are also running massive brake ducts so they can maintain temperatures in their target range, and like you said replace/rebuild on a regular basis.

I wouldn't run them myself, they just don't hold up as long at the track.

I hear you Chris. I am wondering if the brake company folks can't comment because their companies sell both product types...:icon08:

The official brake rotors debate - NISSAN Z FORUM

My opinion means nothing, but I'm going to give it. For racing applications, cross-drilled or slotted rotors are used for a reason. I'm sure the teams have done tons of R&D, but I think part of the reason they run with them is from sponsorship demands.

Personally, I would get slotted over cross-drilled.

Interesting - 2ft longer stopping with the sport brakes? How is that possible? The only thing I can think of is higher weight in the rotors, wheels and tires...

Check out the rotors on my old G35 after a day at Summit Point...:ugh: