TRM

is this the type of damping which provides the most comfortable ride for a track or sport setup?

Jeff Vader - boscoj

level slope at high speeds.<ul><li><a href="http://www.naake.com/wcj_mcj_stj.html">http://www.naake.com/wcj_mcj_stj.html</a</li></ul>

D.C. Lee

... putting a few washers on your struts to smooth out some of the harshness. Other faves of mine are "custom valving," which usually means getting the above-mentioned washers put on an off-the-shelf Koni motorsport or similar shock.

Have we discussed "anti-reversion" headers yet? Don't get me started...<ul><li><a href="http://www.ParabolicaMotorsports.com">http://www.ParabolicaMotorsports.com</a</li></ul>

Singletrack

Good question.

VonK :: Retired

It's also not nearly as magical as its promoters make it sound. As we all know, the resistance force of a standard shock is directly proportional (linear) to its piston speed. The regressive shock has an initial, high linear rate of damping up to approx. 4 -5 in/sec piston speed. At higher piston speeds, the internal pressure simply opens a relief valve, causing the damping rate to DIGRESS from its original linear damping curve to another linear curve of very flat slope. As expected, the damping FORCE never REgresses with increasing piston speed or position.

<img src="http://pictureposter.audiworld.com/12010/shockgraphs3.jpg">

The trick is to get the slope of the initial linear damping curve right so that the damping force at regression (knee) is suitable for bumps that cause higher piston speeds. Not that you couldn't produce REgressive damping by linkage that reduces shock piston speed as a function of spring compression. But that could be done with any shock, linear or digressive. A double regressive shock has the same properties for both bump and rebound.

<img src="http://pictureposter.audiworld.com/12010/shockgraphs4.jpg">

So what is the digressive shock good for? Why limit the high linear damping rate at some point? I remember close up videos of F1 cars running over alligators. Not much wheel deflection. Real stiff suspension and damping to keep the wheels on the ground in turns and during braking. But over the alligators, the suspension really gets a workout that must produce some high piston speeds (resistance forces) in the shocks. If there wasn't some damping relief, it would probably break something.

For the S4, I'm open to suggestions as to what the digressive rate shock can do for us with our relatively soft springs, compared to all out racing cars. If I hit a really big bump, I'd want the shocks to absorb it rather than hitting the suspension stops, because my shocks decided to digress. Until any vendor can produce some honest curves of the nature shown in 3 and 4 above, I can't believe that's what they're selling for the S4, nor would I want it.

Graphs courtesy Dave Weizenhof, NEOUIO Comp Clinic.