Most people know that shock absorbers hold the key to fine-tuning a chassis for optimum acceleration, cornering, and ride quality. And, while it’s easy enough to get an OE replacement shock, the process is a bit more complicated for serious performance enthusiasts. Especially those involved with cars utilizing chassis mods or building a new car for competition or street use. Essentially, it all boils down to knowing whether you need to get a cataloged item or custom build a shock from scratch.
Whether utilizing an off-the-shelf shock or having one custom built, there are, of course, variables to consider. With the help of the folks at VariShock, you can choose from one of three types of shocks (factory preset, single adjustable, and double adjustable). Once that decision is made, they can also help you decide if you want/need a smooth body, coilover, or air spring. But wait, there’s more. To complicate matters, there are even a variety of mounting options as well. You can see how help might be needed.
We got some input about choosing the correct shocks from Chris Alston of VariShock. By the way, yes, he is the same Chris Alston of Chassisworks. His background in chassis and shock design makes him a great resource for this endevour.
There are several decisions that need to be made when selecting shocks, so let’s work through this process in stages. First, we’ll address the situation where the suspension and mounting is as the factory supplied. In many instances like this, what you need is a cataloged shock.
There are many manufacturers offering over-the-counter, high-performance replacement shocks, with factory presets and specific compression and rebound rates. Most of them deliver a 50/50 ratio (the force required to push the shock together and the force to pull it apart are equal). Bear in mind that the amount of stiffness can vary from model to model, but regardless, the force is balanced. Then there are those that have a 60/40 or even many other ratios all the way up to the old 90/10 drag shocks that made it easy for the front end of a car to lift, but coming down was dramatically slower.
There are also adjustable replacement shocks (as well as strut cartridges) that allow the user to change the rate of compression and rebound. Fluid friction is the basis of how most shocks work, and this can be controlled. So, it’s mostly a matter of seeing what’s available to fit your ride and hone in on the features you desire.
Custom Bounce Curbing
We believe it’s easier to tune a shock when there’s a bit more noticeable difference between settings. – Chris Alston, VariShock
Obviously, the first step is to determine what kind of shock is needed: smooth body (for leaf spring and other independently suspended applications), coilover, or air-spring shocks. Once that is decided, it’s time to choose between preset, single, or double adjustable units. VariShock’s QuickSet 1 (single adjustable) actually offers 16 settings which affect compression and rebound simultaneously. Chris noted, “Some manufacturers offer shocks with 24 settings, but there’s really no difference in range. We believe it’s easier to tune a shock when there’s a bit more noticeable difference between settings.”
VariShock’s QuickSet 2 is a double-adjustable unit that allows the user to independently set the compression and rebound. With 16 available settings via each knob, that equates to 256 possible combinations – surely enabling anyone to establish an optimum setting for the prevailing conditions. Once the type of shock to be employed is determined, there’s the need to ascertain the unit’s length, travel, and mounting method.
VariShock uses an eight-digit numbering system to identify their shocks. The first two digits represent the shock body style. Next comes the valving style (factory set, single adjustable, or double adjustable). The next digits represent the base style and hardware. and the top mount style and hardware follow. Finally, the travel length rounds out the required data.
When it comes to mounting the shock absorber base there are several different methods at your disposal. One is a spool eye (with various poly bushings and pins). Another uses spherical bearings (COM-8) and a standard 1/2-inch threaded bore (bushing, stem, stud plate, and clevis fork). Add pivot stem and pivot ball mounts to the list, and within these mount groups are a multitude of different sized bushings, pins, and crossbars.
Poly bushings are generally used on street applications where noise and vibration are of concern. They are stiffer than OE-type rubber bushings, and provide a noticeable improvement in firmness and road feel. The poly spool-bushings are primarily used on non-load bearing installations (like smooth body shocks with remote coil or leaf springs). Poly eye-bushings are intended for load-bearing installations, like coilovers or air springs.
Pivot stem mounts are similar to a spherical bearing, inasmuch as the stem is imbedded in a round bearing pivot. This style lends itself to simple chassis mounts, and is excellent for use in tight areas, as it moves the upper spring seat further down.
The pivot ball offers the same tight, accurate control as the COM-8 spherical bearing, with the added benefit of a maintainable joint. The pivot ball itself is a larger diameter and rides on a low-friction, grease-channeled, polymer race. A threaded retaining ring allows the joint to be disassembled, cleaned, and retightened to retain as-new performance.
Another variable is the base style, which can be standard, 1/2-inch shorter or even 2 inches longer than standard. If a short or long base is employed (primarily for shock body clearances), the difference needs to be subtracted/added to the overall length specs.
When it comes to the top mount, there is the spool eye with its various poly bushings, sleeves and crossbars, the COM-8 Eye (spherical bearing), and the 3/8-inch threaded stem. For coilovers and air springs, you’ll need to add the pivot ball eye setup. Direct replacement 1-inch extended eye mounts are available.
Lastly, the length of the shock and its travel needs to be ascertained. For most applications, the preferred procedure is to put the desired wheel/tire package on the vehicle, remove the existing shocks (if there are any), and set the car at the desired ride height. Then, measure the distance between mounting points. Obviously, the springs employed will be an important factor.
VariShock offers eight different length bodies for its smooth body shocks. These range from a unit that has 2.80 inches of travel and measures 11.35 inches when extended and 8.55 inches when compressed, to a model with 9.75 inches of travel that is 25.30 inches when extended and 15.50 inches while compressed. The installed height should roughly equal the median point between the shock’s extended and compressed length.
There are six available configurations for coilovers and four for air spring shocks. The Builder Shock Program catalog also shows the bump and rebound availability for each shock at minimum and maximum ride height.
Of course, for coilover shocks, the optimum spring for the application must also be selected. VariShock offers coil springs in 7, 9, 12, and 14-inch lengths. They also come in a variety of spring rates ranging from 80 pounds/inch all the way to 750 pounds/inch. In the final analysis, VariShock’s BSP makes it possible for car builders to easily get the correct shock absorber for virtually any application. And, at a cost far lower than you’d expect for a factory special order unit.
So now that the folks at VariShock have outlined what options are available to you, choosing the correct shock for you ride should be a little easier. But, if you want to be assured that you have exactly what you need, you can contact VariShock and talk to a technician.