1981 Honda CBX Road Test - page 3

The CBX fork sliders have been enlarged to take the larger tubes, but are otherwise much as before-featuring fixed damping and Honda's excellent near-stictionless Syntallic bushings. As in 1980 the CBX fork is air-pressurized, at 10 pounds per square inch (plus or minus three psi, depending on preference), but it now has a balance tube connecting the two, fork caps and a single air fitting. Air pressure fine-tunes the fork, which also has a pair of light triple-rate coil springs installed in its tubes.

You may see "Pro-Link" used in advertising descriptions of the CBX's rear suspension and assume that it is the same layout as the one Honda employs for motocross. It isn't. There wasn't room for a large single shock standing above the CBX's swing arm, as space in that direction is occupied by a battery and other electrical components. So Honda lowered the shock and hooked it to the swing arm with a completely different system of links. Only the Pro-Link name is the same, which is fair because even though the parts are different the principle is not: it's a rising-rate suspension. The ratio between axle travel and shock compression is 2.78:1 when the CBX's rear suspension is fully extended; it becomes 1.92:1 at full bump.

Leverage makes the CBX rear suspension progressively stiffer as it jounces upward, and it is made more progressive by its primary reliance on air as a spring. There is a coil spring built into the shock but it's there only as backup, to keep the suspension from collapsing down against its stops in the event that pressure should be lost. In fact, the relative importance of steel and air in this case is revealed by the existence of a pressure sensor and warning light. The shock is supposed to be pressurized between 28 and 57 psi, and if a leak drops it below the lower figure a panel light goes bright red. You are then instructed to reduce speed and seek out the nearest service station.

With the progressive action of the rear suspension's linkage creating progressive damping, Honda probably did not need to provide an adjustment. But they did, with three settings, which are selected by moving a push-pull knob located a few inches above the right-side footpeg. Pushed all the way in, the knob moves (via a clevis and rod) the damper valving to its softest rebound setting; fully out is fully hard, and anybody who can't tell the difference has totally numb hindquarters.

Now that nearly all high-performance motorcycles have triple disc brakes, two in front and one at the rear, Honda could give the CBX distinction only by doing something difficult. That's what they did, creating for the occasion a brake rotor of such intricacy that few manufacturers would attempt to make its equal. Rather than drill the expected pattern of holes through the sides of an otherwise solid disc, Honda cast (in stainless alloy) a rotor much like those fitted on large cars. That is, Honda cast in ventilating holes leading from the rotor's hub to its perimeter. It is a dazzling display of mastery of the foundry arts and admirable even if it actually accomplishes little more than all the drilled holes.

Only the CBX's two front brake rotors are radially vented; the single rear-wheel disc is solid. But the same twin-piston calipers Honda introduced last year are fitted front and rear, which is nice. The calipers use paired tandem pistons to apply braking pressure more evenly over longer, narrower pads, and are said to behave much better when wet for that reason alone. We know that Honda's tandem-piston calipers work well in the wet, and they also seem superior in rigidity.

   

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