joust75

iTrader: (1)

Hey all,

I have a track model and I would like to drill the rotors. Both for better cooling and to have that extra Bling. I think it would look cool in coupling with my Brembo calipers!
The question is... can I do this to my rotors without messing them up or do I have to buy them that way?
If I can do this, what kind of place would I take it to.

Any advive would be appreciated. Merci!

Audito350Z

iTrader: (1)

You are better off buying a set that is already drilled. Stillen sells some and I think Avalon has a set as well.

Any machine shop could drill them for you, but by the time you pay them to do it, you might as well have bought new rotors.

Also... buying new rotors means you will have your OEM rotors handy for when you crack the drilled rotors and need to replace them quick.


PeteH

MaddMatt

The holes are NOT for cooling, and your car will NOT stop in less distance. But they will fill your bling criteria.

westpak

iTrader: (19)

I agree, after doing my first track event I was strongly recommended to stay away from drilled rotors as they will crack under heavy use like track, but it will fill the bling bling need.

dwnshift

iTrader: (1)

In my own persoanl opinon....hate having to type that all the time but.......
Stay away form the drilled rotors......

AndyB

Back in the day.... drilled rotors were invented for old brake pads that would outgas during a hard stop. The gas coming off the pads would actually try to push the pad off the rotor and make more pedal force necessary. I don't think they ever really helped with cooling significantly. They mostly just let the gas out.

Todays brake materials are so much better that drilled rotors are only usefull for show. Modern pads don't really outgas enough to worry about.

Avalon Racing

iTrader: (5)

I have been running drilled and slotted rotyors on the track for years. It is important to do a proper install and combine the correct pad with the type of use the brakes will be put under.

Here is some more data:

Brakes:
Let’s start the basic knowledge on brakes with the discussion of “directional” or not. Sport Rotors (drilled or slotted) come marked for a specific side. This is to optimize their functional cooling and out gassing. Sport Rotors can be used in either direction as they use a piller mounted vein for cooling. The Skyline, Brembo and A/P Brake kits use a radial vein and MUST be mounted directionally.

Now with this out of the way, I would like to provide some basic brake data written by a Racing Brake Development Engineer and myself. The goal is basic brake technology for racing, the street and why certain big brake kits are required. It will also aid you in the decision to use cross drilled, slotted or a combination rotor. Most use cost to determine the type instead of driving conditions. The wrong type rotor with the wrong pad combination in the wrong situations means trouble.

“ Most true car enthusiasts are also committed gear heads. Not only can they wring the last amount of absolute power out of their ride, but still feel the need to take it to the next level.

Human nature being what it is, gives us the creative impulses to focus on power increases. The need for speed, while commendable, often comes at the expense of balanced power and delivery output and consumption. To create a truly great car, one must deliver all facets into account and make them work together. Simply put, the faster you accelerate, the quicker you need to stop. Cars that accelerate like an F-40 but brake like a Pinto on greased drums are very common. This is not only one of the slowest ways around the race track, but the most dangerous. Powerful fade – free brakes are a true characteristic of a noteworthy performance car. Oddly enough, many drivers do not take the time to fully understand the mechanics of the modern braking system.

The Principles: (applied in road racing and circle track)
Brakes function by turning kinetic energy into heat energy that can be released into the air, allowing the car to slow down or stop. If you remember Physics 101 in school, energy is neither created or destroyed within the system, it only changes form. Any object in motion has kinetic energy, and will tend to stay in motion unless acted upon by an outside force. You can calculate the amount of kinetic energy by this simple formula: Kinetic Energy=WxS2/29.9 where “W” is the weight in pounds of the car and “S” is the speed in MPH). Assuming your car weighs 2500 lbs. and travelling at 70 MPH, than you are strapped to 409700 ft-lbs. of kinetic energy. Ahead is a sign posted at 20 MPH ( for the turn). It is critical that we convert some of the energy so that we can take this turn in a controlled four wheel drift. To take the turn we will have to convert 376255 ft-lbs. of energy into heat. The formula for this is – [ 409700 – (2500x20 2nd / 29.9)] This will require a lot of friction and where a modern braking system comes into play. The rest of the article will give you an idea of the demands put upon the vehicles stock braking systems. While it can be done, you will see that with a modified systems the demands will be less strenuous on the brake system and the vehicle will have a higher recovery rate of heat to dissipation of kinetic energy.

I really need to note here that most if not all upgrade charts talk about power (in horsepower). BUT, it is my contention that regardless of who’s chart (Stages) you use, the need for improved brakes and suspension starts at Stage III.

I’ll leave out the rest of the variables as they will only confuse the basis of this article. Essentially, what we are all trying to achieve is to stop the car repeatedly and safely. By using cross drilled rotors for their intended purpose (performance street driving and limited track use) you can increase your performance greatly – provided the right heat range pad and fluid combination is used. Cross drilled rotors provide better initial bite characteristics. They will be more aggressive under lower temperatures and be able to vent out gasses to a much higher degree than a stock rotor and pad combination.

Generally true race cars use either a combination of drilled and slotted or just slotted. This is due to the fact that their fade characteristics will lessen at higher temperatures. Let’s look at a 100% road race car for example.

These cars will use a slotted (and drilled at times) rotor exclusively due to the high demand that they put on the brake systems. These rotors will provide better braking at higher levels usually seen at an open track (circular) event or even endurance race. While these rotors work well under these conditions, they may not be suitable for lower temperature and low demand road race tracks.. They can hinder the braking capabilities due to the fact that they will need higher temps to work efficiently. Open road course events should be taken under more consideration. At race tracks that have long straights and deep turns, slotted rotors would be the preferred rotor due to its ability to out vent at higher temperatures. Rotor and pad combinations should/must be taken into account as well. Usually at an open track event, much more aggressive pad combinations are used. When using these combinations you will generally have to deal with a trade off in wear in either the pads or the life of the rotors. More aggressive pads will create more heat and friction thus causing accelerated rotor wear. Less aggressive pads will cause brake fade and accelerated pad wear. Do not forget that by using a pad that is too aggressive will cause the rotor to wear and require heat to work well. In some cases a pad can damage a rotor causing failure and damage. The balance could mean the difference in victory or failure.

So what does this all mean, besides you should choose the type rotor, pad and brake system for your needs?

You just read the math and examples as well as some simple rations and characteristics – Now lets put them to use. Think about your particular application. While we all wish that we could out brake the world best drivers into turn one at LeMans, lets look at reality.

STOP – Sit Down – Have a drink (non alcoholic of course) and ask yourself the question:

While it is possible to put a monster brake system on your car you may never have the need or ability to use them properly. A big brake kit may look awesome but could leave you disappointed. You may never be able to get them to proper temperatures. For daily drivers and weekend enthusiasts, you may only need to go the way of the cross drilled / slotted rotors and a carbon based pad. I write this under the assumption you already upgrades your brake lines and fluid.

As I have also said numerous times – proper installation and break-in / seating of new rotors and pads is critical. Improper installations and mis-use is the number one cause of warped or in some cases cracked rotors. Never start the break-in of rotors is the run-out is more than 5 thousandths.”

Hope this helps.

Copyright – Avalon Ent – Racing Division – All Rights Reserved

Avalon Racing

iTrader: (5)

While there are many rumors and home made theories about the benefits of different rotors, lets try to dispel them and deliver some facts. Cross drilled rotors have long been the subject of ridicule and blame. For years so called racers have been blaming poor old cross drilled rotors for failures that were not directly related to them. Cross drilled rotors were designed with the intent that cool air would pass through the rotor to help reduce the heat deflection through the rotor. An interesting fact about (all)"vented" rotors is that they pull air from the center of the rotors and allow it to pass in an outward direction. By cross drilling the rotors, you can achieve more cool swept area of the rotor and pad while sweeping the pad and rotor surface at the same time. This is very beneficial for performance and daily driving. The cross drilling also makes the rotor surface more aggressive to give a better initial bite under heavy breaking. Many wanna be "Racers" believe that all cross drilled rotors are prone to cracking. One of the things that they don't understand is that all rotors are prone to crack given wrong or extreme conditions. The difference is the heat threshold that each of these rotors will allow.

A slotted rotor will have a higher thermal thresh hold but can still fail. One of the most overlooked reasons for brake failure is mismatched pads and rotor combination. With out the correct combination, your performance level could really be at risk as well as your safety.

Just because a rotor is cross drilled does not mean that it is at risk to fail or crack. Many manufacture's use different methods to help prevent rotor failure. One such method is to radial chamfer each gun drilled hole in the rotor surface. This as you may recall from physics class makes the edge stronger. (a curved surface is stronger than a flat one). By doing this you also make the rotor more aggressive with out making them more abusive toward the pads. This also allows for more air surface for cooling.

Slotting the rotors is generally intended to pick up where cross drilled rotors leave off. They tend to have a higher thresh hold to heat there for enabling the brakes to function at much higher temperatures. By slotting the rotors you create "sweep" for the pads. At high temps cross drilling becomes non effective. Rotors can't pull air through after extreme temps. The rotor actually becomes a heat sink. As the cross drills become non effective, the slots can sweep the gas pocket out. For a real world example, look at "real race" cars. Mainly, road race cars such as Trans Am, IMSA, and CART will exclusively run slotted rotors with very aggressive pads. While many teams have their particular love of brand, they all have the same basic function. One must also realize that when operating a performance system, there will be a trade off in the system some where. Generally performance street systems are designed to compromise the pads life with added braking ability. By doing this, one can expect certain "better" braking while not sacrificing the life of the rotor.

As you move up in pad compound, you must realize that it takes more heat to get these brakes working at optimum standards. The trade off here is accelerated rotor wear.(Here's were combination playing can pay off / or not). Ideally, you would want to run a new pad on a used rotor and vise versa when seating new components. Depending on the track conditions and characteristics of the particular car, bypass stagger (brake ballast) in conjunction with pad and rotor combo can be the deciding factor in longevity and performance.

For most import and domestic applications, there should be little more than a need for basic cross drilled or slotted rotors with carbon based pads and steel braided lines. Not all big brake kits are practical for each application. They may not even be available for your car or truck. The last important factor is to take into consideration is driver charctoristic's. Late braker's will generate more heat cycles than a "two footed" driver. The dreaded "two foot" driver will just eat brakes period.


Regards

Importlife.com

joust75

iTrader: (1)

Thanks guys for your time.

I have always valued function over form, so I guess no drilled rotors for me

What got me thinking was seeing them on the AMG models out there

westpak

iTrader: (19)

If you want the look get them drilled if you want, just make sure it is someone that knows what they are doing, the holes wont be a problem for street driving if done properly or if you buy drilled rotors they are a problem if you are going to track the the car.

MaddMatt

Bling!

For the record: My job is to stop cars. I go to the track A LOT. I have crewed for Trans-Am teams (the race series, not the Pontiac), walked the garage at IRL races and had some up-close and personal time with former Team Oreca Le Mans Viper GTS-Rs. No, not trying to impress, my point is this: On none of these cars did I see one crossdrilled rotor. Not one, ever. There's a reason.

westpak

iTrader: (19)

Matt, are you guys working on a track pad for the rears and fronts for that matter?

I went out the track and my stock rears were toast but a friend of mine had the bocats in back and the Hawk + in front and they got toasted as well as his rotors.

MaddMatt

Absolutely. I answered your question in the other thread.

deviousZ

I have never seen cross drilled rotors crack but I have heard about it. I was thinking about this also brembo sells cross drilled rotors to go with the stock brembo calipers. I would say that only in extreme track use would they crack. I think you should get them bling bling!!!

Avalon Racing

iTrader: (5)

We run GT-2 and see cross drilled rotors on alot of cars at every event. I see them on Trans Am cars, Nascar (track dependent) IRL and Cart also use them as does F1.

Also all the exotics, like Porsche, Lotus, Lambo etc utilizd drilled and/or slotted rotors.

Almost all big brake kits come drilled or slotted. Most cracking occures from the following scenarios:

In proper install and the run out is not checked - torque on the lugs are not even - the hub surface was not cleaned properly and the fact that peopl ewill push the rotor and pad combination past the heat threshold of that particular set combination. Then you have the fact that some manufacturers use low quality blanks to keep the cost down.

This issue has been discussed numeorus times on other forums for all types of cars. The bottom line the majoirty of users do not have a problem with drilled and/or slotted rotors if they are a quality product.

The product MaddMatt is talking about is the product the company he works for sells. I have never heard anything bad about the product -

SO in essence it really is up to the buyer to make surre they get the best pad/rotor/caliper combination for the type driving they will be doing.

my .02 worth..........

Regards

MaddMatt

We actually don't sell cross drilled rotors. Our product liability insurance will not cover us due to failure rates.

Never seen a crack? Go to the track. Over half the x-drilled rotors I see are about to fail. As a club tech inspector I would fail cars with x-drilld rotors for cracks.

Let's get down to it, wht are these cross drileld rotors for? Street? Track? If you're only driving on the street, I can say you'll likely never have a problem with cracking. The brake temps on the street just don't get that high. So, go ahead a get them, as long as you don't mind spending an extra $2-300 for no measurable performance gain at all.

This topic is one of my hot buttons. Click here for the best x-drilled discussion ever.