Originally Posted by AP - Chris_B

Bias is definitely not irrelevant as ABS does not alter the laws of physics. But it is a moving target. What I mean by that is if you dial a brake system in for a completely stock vehicle at stock ride height and stock spring/dampers, you won't have achieved a 100% optimum balance for a lowered car with stiffer springs and dampers. Why? Because now the vehicle's weight doesn't shift forward as much for the same braking effort. Therefore, more braking can be done by the rear tires. Fill the gas tank and put a passenger in the car and now the numbers are different yet again!

A few years back, I was working for an Indycar manufacturer. We would spend countless hours in the wind tunnel working with aerodyanmicists to keep the center of downforce pressure from shifting forward under braking. When the nose goes down and the tail goes up, the venturi effect of the underwing/tunnels is weakened. Losing rear downforce causes premature rear wheel lockup under heavy braking at high speeds. By changing certain aspects of the tunnel design, we were able to significantly reduce this shift. That way, the driver was able to dial the brake bias rearward if the track conditions would allow it. Those cars were unbeatable under braking as was proven at many tracks that season.

The point? Proper brake system balance is a compromise between a vehicle's dynamics, estimations of how the car might be otherwise modified and by how much, available components and a list of other factors. Plus, no one should be required to change their master cylinder (race cars have two brake master cylinders that can be easily swapped for slightly larger or smaller ones, plus a balance bar the driver uses to dynamically fine tune front/rear bias while on the track as the fuel load changes). Consider all this and you may start to understand why this level of detail is not published.

I can offer this: If the brake system bias is wrong for the car and it is pushed hard, everyone the buyer knows will hear about it. The Internet makes sure of that these days. Talking directly to those who have the system on their car and are of sufficient skill level to make a reasonable evaluation will often yield better results than listening to a manufacturer's talking heads or browsing through web sites. These systems are just too expensive to put on the market and risk negative feedback. Sure, some will like one brand over another. But put a few bad kits out there and your name turns to $h!t quickly. AP Racing and Stillen just can't take that chance as they have almost 40 years and 24 years, respectively, of reputation building at stake.

If you are going to be seriously competing with your car, AP Racing makes a variety of professional racing products that are fully adjustable for any track you wish to compete on. Just be sure you bring a lot more than $5k! But for street/track day kits, that amount will get you nicely dialed in for years to come.

And, no I'm not mad. I have 3 kids, so forum discussions are no match for those professional button-pushers! I do take issue, however, when unfounded claims are made out of thin air with no supporting evidence. I have no idea what you do for a living, but if someone claimed without cause that you simply pieced your work together instead of approaching it professionally (especially if peoples' lives depend on your efforts), you might take issue as well.

Cheers,

Chris