al503

Your points are well-taken, bux. However, your focus is on the wrong component, at least IMO. The main concern in brake fade is not the caliper design (as long as it's relatively well designed). It's the heat capacity of the rotors. The aftermarket BBK's have larger diameter rotors, they have better venting vanes, and there is more rotor mass, which will simply absorb more heat. The M5 and M6 have single piston calipers but large rotors.

If someone offered a two piece rotor in the same diameter but had better venting and more mass/heat capacity, I would definitely go that route as it would be much cheaper, and the rotors themselves would be lighter (the aluminum hats reduce a lot of unsprung rotational weight).

Stoptech doesn't plan on offering their aerorotors for the IS. Project mu might but I'm not willing to wait for something that I don't know will happen or not.

Gernby

iTrader: (1)

PM sent. I don't want to steal the thread ...

lobuxracer

iTrader: (2)

I disagree about the heat capacity. I'm not going to run a disc any heavier than I need with the cooling methodology I have in place. All I care about is the disc not fragging and the brakes not fading. If I can blow air through them, the fin design will be inconsequential. I've been through the calculations with curved vane and straight vane discs and the difference is pretty much academic if you just ensure good airflow through the vanes.

The rotor has one job - convert kinetic energy to heat. If I am not applying more heat than the rotor can dissipate to maintain the preferred pad temperature range, then all is good. More mass != better in all cases.

I completely concur with lower unsprung weight, but again, a heavier disc is not only unsprung weight, but possesses greater rotational inertia in the worst place - far from the center of rotation. It's all about balance. Having worked with both asphalt and dirt racing, I can tell you there are times when you'll want the tiniest rotor you can get, and other times you'll need so much mass and airflow that you'll be putting a pump and heat exchanger on the brake fluid to keep it from boiling in the calipers (a la NASCAR short track).

al503

Again. All very good points. You are absolutely correct that the weight on the 2 piece rotors is the furthest away from the axis which affects MOI. However, this is offset by the total reduction in weight if not more in most cases.

As to your other points, can't disagree with them. I don't plan on ducts unless someone comes out with a bulletproof, solid kit. You don't want that thing coming loose at speed and I've seen 'homemade' ducts get scraped off at places where the suspension is fully compressed. I also don't know how feasible this will be for the IS in that will be as there is really no room (unless you're going in a straight line) to work with between the tire and fender liner. You would have to have the tubing go underneath the body of the car where you only have about 5-6" at most between the car and the ground at rest. I plan on lowering the car at least an inch (2" if I get coilovers and I'm at the track) and when you add that to the compression from the turns, you have maybe an inch or two to work with.

lobuxracer

iTrader: (2)

I wonder how many people would be seriously interested in a ducting kit. I'd want to do a CF backing plate with a solid connection for the tube, then I'd need to figure out how to route the tube. Yes, clearance and damage to the ducting are always big problems. Even worse is the guy who wants to run these on the street because it's a racecar part.

I'll have to think about this for a minute.

itsme4g63

I guess any type of brake upgrade is a good thing, safety factor and all, but spending 6k on brakes for a lexus, you must be a.) racing the living ****e out of the car or b.) wanting to bling bling around the city with your dubs. There is absolutely no point in gettin a such a brake system, I would think powerslot rotors and hawk pads would work great as an upgrade. But to each his own.

lobuxracer

iTrader: (2)

I just noticed in the New Car Features that our OEM front rotors (on the 350) have curved vanes for improved airflow. So they did go the extra mile to add the last percent and a half or so. I wonder if they're as cheap as Supra discs (~$70).

CRB

How do this StopTech's compare vis-a-vis the Endless systems that were posted on this board a while back?

I notice this thread is staying on topic a lot better than the bash-A-thon the Endless thread turned into.

al503

Endless is considered to be Japans best and people compare them to brembo and alcons (with alcon arguably considered the best anywhere.) Stoptech is still probably considered 2nd tier compared to the above, but they have a very good presence in the motorsports and they're popularity is catching on.

The biggest difference is Stoptech takes brake bias (front to rear) into consideration and their front kit can be used with the stock rear brakes. Endless recommends using both their front and rear kits for best results. You can get just the fronts in the Endless as cars with EBFD do apportion bias front to rear depending on grip.

Gernby

iTrader: (1)

I've always felt like OEM brakes were already biased too much toward the front, especially if the suspension and tires are "upgraded". Since most people would upgrade their suspension before upgrading their brakes, how would it be possible to upgrade the front brakes alone without screwing up the bias even more? If anything, I feel like I want to upgrade my rear brakes, and leave the front brakes alone!

lobuxracer

iTrader: (2)

The bias is controlled by a computer, not the typical proportioning valve. The computer balances the brakes on every stop, so they don't feel consistent. I've experienced the same thing with my Scion, and I can't say I like it after having mechanically proportioned brakes for 25 years or so. I'm not convinced EBFD is a mature technology at all.

EBMCS03

DANG! $6K. They'll look awesome!!!! but the stock brakes work GREAT for me on the road... stops just as fast as a BMW. hahahaha so i'm good. I already out brake like 99% of the cars on the road I dont need better brakes so they can ram my rear.

al503

They can get the bias by varying the pad shape, piston size, etc. Stoptech just could have offered both their st-40 (smaller pad, 4 piston caliper with less piston area) along with the st-60 that they are offering but they won't because the st-60 has similar braking ability/bias as the stockers.

al503

Gotta disagree with you about EBFD. The best here according to R&T is the F430 at 107 and 191 ft for 60-0 and 80-0.

A g35 coupe with EBFD did the same in 112 and 199 ft, which is about what the 911 Turbo can do. Both of the other cars have much better front/rear weight bias, lower center of gravity, etc. EBFD (at least Nissan/Infiniti's) can work wonders.

I haven't slammed on the brakes in my IS yet but I'm hoping to get the same kind of performance.

Gernby

iTrader: (1)

That's interesting about EBFD, but I imagine it would work better under ideal straight line tests than it would in real world / track environments. I still get frustrated with ABS pretty regularly during my commute to work on bumpy surfaces.