Join Date: Jan 2017
Location: Baker City Oregon
And the answer is..! I copied this since it answers nearly every question I had.
The Honda TRAC system differs somewhat from the ADVS-style units. Honda maintain that hydraulic systems have two basic drawbacks. First, the additional brake-line plumbing and increased brake-lever ratios can produce a spongy feeling at the brake lever. Second, those systems are either on or off - there's no modulation of antidive effect. To get around these problems, TRAC is instead activated through the torque reaction of the brake caliper itself. This makes it completely independent of the hydraulics in the brake system. It works because one of the two front brake calipers is hinged behind the fork leg on a pivoting link, rather than being solidly attached. When you apply the brakes, the pads grip the spinning disc and this tries to drag the brake caliper around with it. The caliper pivots on the link and presses against the anti-dive activating valve which is built directly into the fork leg. From then on it, it works just like the Yamaha and Suzuki systems, restricting the flow of fork oil and stiffening the suspension. The advantage of the Honda system (they say) is that the harder you brake, the more pressure the pivoting caliper puts on the control valve, and the stiffer the suspension gets. One important difference with TRAC is its ability to deal with the bumpy road surfaces which the other systems had a problem with. The TRAC valve is a floating piston held in place by a spring. This means that if you hit a bump, the sharp and sudden increase in the pressure of the fork oil can override the anti-dive valve and force oil through the valve as if it were not applied. This means that TRAC can respond to bumpy roads whilst braking. Clever eh?