There's a multitude of ways to build a performance machine, but at the core of the whole enterprise we all want the same thing: to get the most out of what we have. In fact, you can boil down what we want our combos to be in one word, optimized. The dictionary defines it as: "To make something function at its best or most effectively, or use something to its best advantage." Good word, eh? In fact, it's a word that came up frequently during our recent discussion with Chris Alston, proprietor of Chassiworks and maker of the VariShock line of adjustable shock absorbers. We set out to explore single-adjustable versus double-adjustable shocks and also touch on why both of them far outclass nonadjustable shocks when it comes to optimizing a performance automobile.
What Does A Shock Absorber Do?Dissertations have been written on the subject, but the answer is actually pretty simple. In short, shocks absorbers control how the suspension works. While springs hold up the car, supporting its weight, shock absorbers damp the oscillations that occur as the springs move up and down. They never totally remove the oscillations, but in more simple terms, shocks control the bounce that springs would normally exhibit.
What's Wrong With Regular Old Shocks?We admit that this is something of a strawman argument, but since plenty of people buy traditional nonadjustable shocks, we felt like it was worth tackling. The bottom line is that an off-the-shelf, nonadjustable shock has the wrong damping for your car-period. Actually, there's one exception to this rule. If you've got a totally stock machine with everything in perfect working order, just as it rolled off the assembly line, and you buy a shock made for this arrangement, you're probably in decent shape. But how many of us are dealing with totally bone-stock setups?
Anything that has an effect on the suspension means the shock damping is wrong-bigger tires, more powerful brakes, lowering the vehicle, changing air pressure in the tire, literally anything-including changes in driver style. As soon as you change it, the shock is wrong. Of course that sort of belies the point, because in this arena, most of us as dealing with nonstock setups of one type or another, and we're more than likely driving our classics far beyond what their creators ever imagined.
The number of variables is extensive, and choosing the right nonadjustable shock for any of these many combos is damn near impossible. "If I could guess what your valving should be," quipped Alston, "I'd quit making shocks and buy Lotto tickets."
The bottom line? Anything that changes or affects the suspension means the system isn't optimized. And remember, optimized is what we all want.
What We Did
Talked with Chris Alston about the pros and cons of single- and double-adjustable shocks
Double-adjustable shocks are the best way to optimize your car's suspension
Single-adjustable shocks are...
Single-adjustable shocks are pretty straightforward. By turning the knob, you either increase or decrease both rebound and compression damping. This is illustrated by this graph from Alston's shock dyno. As you can see, however, the rebound damping increases more than the compression damping-there's a usable range of adjustment, making a single-adjustable shock far superior to a nonadjustable one. It is limited, however, since both shock actions are adjusted together through 16 settings.
This is illustrated to good...
This is illustrated to good effect on this second graph from Alston's shock dyno. As you can see, there's a much greater range of adjustment to be had. Better yet, since the two are independent, it's possible, for example, to adjust rebound damping (coming apart) to full soft and compression damping (coming together) to full firm. That's an extreme example, but the bottom line is that you've got access to 256 possible combinations-meaning the right one is in there somewhere.
A double-adjustable shock,...
A double-adjustable shock, on the other hand, comes with two knobs and allows rebound and compression damping to be adjusted independently of each other.