mic_crispy

[QUOTE=Tugz_S2K,Oct 8 2006, 02:25 PM] hOLY fACCK

RED MX5

There may actually be more surface area (for cooling) due to the holes. If the hole diameter is less than the material thickness then the surface area is increased (the area inside the holes counts too). However, either holes or slots will releave the gas buildup between the pads and rotor, increasing the pad contact effeciency, and improving total breaking power - that has a side effect of producing additional heat in proportion to the improved breaking effeciency.

IF (and I don't recommend it) you're going to cross drill rotors you want to round off the entry and exit points (a sharp edge will increase stresses dramatically and promote cracking), and I'd also want to do some kind of stress relief after the drilling was completed (shot peen, or something similar).

In general, if the stock brakes (on any car, not just the S) aren't up to the tasks you're throwing at them it's best to work up complete system that wil handle the tasks at hand. Just getting a stream of cool air to the brakes can make a huge difference. Notice that on most race cars with holes in the rotors you also find a set of ducts that bring cool air to the rotors and blow it through the holes. That's really where they help with cooling.

RED MX5

If the rotors are designed with the cross drilling (or cast in holes) taken into consideration then they're probably safe. I'm paranoid about cross drilling (actually drilling the holes on a milling machine) because I've seen too many failures, but that's not at all the same thing as designing a rotor with holes or slots.

BTW, no matter how many people say otherwise, giving the gasses an exit actually improves contact between the pads and rotor, so the "loss of breaking surface area" idea is meaningless. You get a higher coeffecient of friction with slots or holes because you're pads press directly on the rotor, and that works much better than squeezing the gases hard enough to stop the car.

A good breaking system involves a bit of design work and consideration of the entire system. Any brake mod that fall short of that is either shade tree work or bling.

If the rotors in question are made by a reputable company they're probably safe. Companies that market rotors that crack usually don't stay in business very long.

RED MX5

Amer, I don't know if that's true in all cases, but many of the brake upgrades I see on cars are illconceived and ineffective, even when the high priced components are used.

Bigger brakes won't stop the car any quicker, unless the traction is upgraded to the point that the stock brakes are overpowered. Overheating is another matter, and the amount of cooling needed varies depending on the driver. We had a wonderful example of this at SESM 2004. Just before the lunch break, another member of S2kA (Tom) and I started two cars from the back of the line and blew past the entire group. We weren't racing, but we were doing a good job of burning up the road. Then while waiting in line for lunch we heard a couple of guys behind us, guys who had been driving a LOT slower than we'd been traveling, complaining about their breaks fading. Before I shot off my mouth I asked Tom if he'd had any problems with his brakes (he hadn't, naturally), and then I couldn't resist telling the guys that if their brakes were overheating that meant that they were using them too much.

Some drivers heat up brakes much quicker than others, just as some are easier on tires, fuel, engine, clutch, and so on. Being "easy" on the parts doesn't necessarily mean the driver is slower either. Usually the fastest drivers get the longest component life out of every part of the car.

While it's just my personal opinion, I think anyone who is overheating the stock S2000 brakes on the street is either driving way too fast, or way too slow (and using the brakes excessively). On the track it's another matter.

mic_crispy

i thought modern pads did not emit much if any gas at all?

RED MX5

You could be right, but I suspect it depends on the pad material, and I really don't know how much gas the OEM pads on our cars produce. It doesn't take much to prevent the pads from achieving maximum grip, but of course if the brakes are up to the task at hand it's not a problem anyway.

I believe that the solid material that is being worn off the rotor and pads also reduces the friction, and slots or holes also give it an exit too (as does the grove in the brake pad).

If the pads (and rotors) don't produce any residue that reduces the coeffecient of friction then slots are going to be useless. You can't force air through slots the way you can through holes.

trivium

My car isnt a daily driven car. Its a trailor queen. So I need some cheap nice looking rotors. Care to share?

RED MX5

[QUOTE=pdiddys2k,Oct 8 2006, 09:07 PM]These rotors were

RED MX5

"Trailer queen." That's great!

I just wanna know how a trailer queen can be a daily driver?

trivium

I just said my car isnt a daily driver. So now I am confused as to why you asked me that contradictory question