[hqen2000]

Pads and fluid is all you need. They're vented rotors. You can drill the stock ones if you want a tiny bit better cooling, but otherwise I don't see how it would make that big of a difference. The car has ABS which is sometimes odd with a break upgrade. You don't know if you need to upgrade the front, rear or just both. With the Turbo Mr2s we used to track we'd just gut the fluid manifold to apply even pressure to the front and rear and that would give lots of brake force. Plus unless you are running really sticky tires you'll have far more issues with lockup before you need to upgrade the brakes. If you want something that just looks cool paint the calipers and drill the rotors.

I also have a Spec Miata full racecar and all we run in those are stock rotors, race pads, and race fluid and it'll take me from 110 to 60 in a no time to make turns, this is on a track where if I mess up it can be a disaster.

 

[hqen2000]

QUOTE (Doc_V @ Jun 15 2010, 12:12 AM) index.php?act=findpost&pid=333086

FYI- The truth behind cross drilled rotors is often misunderstood. First and foremost, it has nothing to do with cooling; that is a misnomer. The original intent of cross drilling rotors was solely for weight saving purposes. Porsche was the first to try this back in the early 1970's at Le Mans with the 917's. At that time Porsche was drilling holes in just about any piece of metal they could without sacrificing structural rigidity. Believe it or not, they even drilled holes in the key. It may not seem like a lot, but added up, every ounce counted, which can make a difference of a win or a loss over a 24 hour race.

In the case of cross drilled rotors, what Porsche found is it also added in the dissipation of gasses that built up from the brake pads which was *one* of the causes of brake fade in the early stages of the race. When new pads or "non-bedded" pads are used hard for the first few times, heat causes the adhesives, used to bind the brake pad material together, to release gasses. These gasses build up between the pad and rotor causing the pad to "float" and loose much of it's braking force. What Porsche found out that in addition to the weight savings from drilling rotors, the holes provided a means to evacuate the gasses and minimize brake fade. However, over time, they found out the down side of cross drilling rotors was it severely compromised the structural stability of the rotor. Throughout a race, brakes would "heat cycle" several times a lap going from glowing red-hot to much cooler temps. This caused the rotors to expand and contract over and over until the metal began to fracture. In some cases, the rotors would literally "explode". Fast forward and modern brake manufactures now know they can achieve the same "venting of gasses" by slotting the rotors, without sacrificing safety. Please reference the links in my previous post for more details; I'm too lazy to do it again.

If you drill holes in your factory rotors, you do so at your own risk.

If you look closely at a "vented" rotor, [which the Sonata has] they are actually *two* discs, sandwiched together with cooling vanes cast in between them. See fig [A] below. These vanes act like fan blades, pumping air between the discs to aid in cooling. The problem with drilling a factory rotor is it's almost impossible to do so, without hitting those vanes which further decreases the strength of the rotors. In the case of the cross drilled rotors found in most "big brake" upgrade kits, they are actually rotors from Porsche. Porsche took the time to "cast" the holes in between the vanes to insure no loss in structural stability. Even so, they too still develop small but visible fractures in each hole. See fig (I have personally witnessed this when I ran them on my Porsche race car.) Some race clubs have actually begun to ban crossed drilled rotors for this very reason; while even more are considering it.

In conclusion, I'll be the first to admit, cross drilled rotors look very cool and if all you do is normal driving on the streets, you'll probably be OK; but that's a lot of money to spend on just looking cool. That said, if you intend on doing any *actual* hard driving, your much better off with slotted-only rotors.

Fig [A]

Fig

Vented Rotor is not a xdrilled rotor. A vented rotor is merely a rotor which is hollow in the center, it adds a SIGNIFICANT amount of heat dissipation. As opposed to a solid rotor like some older cars do (and many newer cars do in the rear). I think you are generally better off just using a superior pad and fluid and changing the rotors and pads more often. This is what most people with track cars do (and racecars). But be careful and make sure you get pads that work cold. Some pads need to be warmed up. Also a lot of race pads make noise and produce a significant amount of brake dust over 'standard' pads.

Most people just want big brake kits to look cool though, not to provide superior stopping power. If you want better stopping power first look at your tires, then look at fluid. Is fade the concern? Or stopping distance? I'd say the vast majority of the time big brake kits provide reduced stopping ability because they just overbrake the front tires and the rear still suck. I know MOST of the braking is done in the front, but there is also a significant amount of braking done in the rear.

I had a supercharged MR2 racecar and the most we ever did with those is gut the stock brake manifold to provides equal braking pressure to the front and rear, but that depends on a bunch of different variables such as weight balance.

If you want to provide better performance for a car the first thing you should do is just get better tires. You can do fancy suspensions and brakes, I can take my stock sonata out with a set of R compound tires and walk allover you at the track. Big brakes are for cars with big power, which the Sonata is not. So I don't really get it anyway. With a car as underpowered as the sonata (relatively, if you are racing on a track) you should learn to drive faster and less on braking. The best racers often keep the braking to a minimum under most track conditions. You want to go fast not slow. Braking does the opposite of the accelerator so if you are using it too much you aint going fast.

 

[hqen2000]

You need to decide if you want superior performance or looks or the best blend. There is nothing wrong with being a ricer. To each his own. If you want a brake upgrade because it looks nicer, do it. I get tired of people discouraging other people from just doing what they want to do. Its your money. You know that it might not improve your braking much, that's fine. It might even make it worse, that's fine. Will it look like you have a fast car with big brakes? Yes. If that's your goal go for it!