Single Adjustable Vs. Double Adjustable Coilovers and Shock Absorbers

You’ve found your dream car or truck and want to update or upgrade your shocks or coilovers. There’s low-priced, over the counter shock options with little to no features. There’s also fully tunable shocks and coilover options with tons of adjustment that also come with a hefty price. What’s the difference in shock adjustability and what setup is right for me and my vehicle?

Shock Absorber 

Most vehicles developed on the road over the last 100 years have been equipped with coil springs/leaf springs and shock absorbers. The springs are designed to support the vehicle weight (The springs hold up the vehicle). The shock absorbers do just that (They absorb bumps and friction as you head down the road or trail). As the vehicle travels down the road, the shock absorbers are controlling the springs and the two are working in unison to go smoothly down the road.

Twin-Tube Shocks

Twin-tube shock absorbers use an internal tube inside of the shock body that the shock piston travels in as the shock absorber cycles. Many on-road vehicles and OEM applications come from the factory with twin-tube shock designs. Shock tuning in these type of shocks can be designed by the use of a base valve, piston design as well as piston shims used  to control the flow of oil through the shock absorber. 

Monotube Shocks

Mono-tube shock absorbers are designed where the shock piston rides on the internal wall of the shock body as the shock cycles. On-road, off-road and several other applications are where you can find this style shock design. Shock tuning in a monotube shock is typically done through the use of specially designed pistons and piston shims.

Shock Adjustment

Shock absorbers can be non-adjustable, single or double adjustable (There are triple and quadruple adjustable shocks, but we’ll save this for a future article). 

Non-adjustable shocks

A shock may have the valving pre-set from the factory and in this case, we call these non-adjustable. The piston, piston shims and internal shock design will establish how the shock performs and there is no external shock adjusters to control the rebound or compression settings of the shock (These adjustments have been designed into the shock by the factory). Non-adjustable shocks are what the majority of new cars and trucks are equipped with as they roll off the line. 

Single adjustable shocks

In a single-adjustable shock, the benefits of a non-adjustable internal design are there; but there is also external adjusters that can be used to fine tune either the rebound or compression shock settings. Most performance shocks you’ll see on restomods, 4-link and custom chassis suspensions are single adjustable. Single adjustable shocks are easy to adjust and once you have your external adjustment set to your liking, you’re good to go. Single adjustable shocks are most commonly used in street performance vehicles looking for a better ride quality than what factory or basic, non-adjustable shocks will provide.

Double adjustable shocks

With double-adjustable shocks, you have the internal shock design + the capability to tune your rebound and compression adjustments for even greater performance and control of how your suspension operates at the track or on the road. By controlling both rebound and compression in a shock, you’re controlling the full range of the shock’s speed and how that shock will react under hard cornering, hard accelerating and the transfer of power from the motor to the suspension and eventually the wheels as the vehicle travels down the road or track. On a double adjustable coilovers, we typically see these used in autocross, drag race and road course applications. You can run a double adjustable on street applications, but unless you’re using all of the adjustment capabilities of the shock – Your suspension may be more suited for a shock with less adjustment. Double adjustable shocks are typically more expensive as they use more parts and components in their design when comparing to non and single adjustable variants.

What about Coilovers?

Coilover shock technology is a newer form of shock and spring technology typically found in performance vehicles and suspension designs. A coilover is the combination of a shock absorber and coilspring. On a coilover, the shock body is not smooth, but threaded. With the body threaded and using a spring retainer and spring collet, the coil-spring can be installed onto the shock. Once the coil-spring is installed onto the shock body; using a spanner wrench or an electronic setup – The coilover can be adjusted up and down. This adjustment on a coilover is call the “ride-height adjustment.” 

Controlling the ride-height with a coilover is another way of saying you’re controlling the stance of the vehicle. This is one of the major benefits of a coilover shock setup. You gain the tunability of adjusting your shocks ride height to eliminate fender gap, clear larger wheels or tires, or adjusting your coilovers to set the spring preload which is another level of suspension tuning.

The most common damping  adjustments coilovers come in are non, single and double adjustable (Similar to the shock absorbers we discuss above). You combine the capability to tune your shock speed, plus select spring rate, determine spring preload and setting your overall stance make coilover suspensions one of the highest levels of performance suspension upgrades for classic or late model vehicles.

Single adjustable shocks and coilovers are great for the street and offer a wide range of easy to tune shock adjustment. Single adjustable shocks typically have a lot of technology designed into them which can offer a smooth and controlled driving experience.

See how easy it is to install Aldan American’s coilover conversion kit on this C10:

Double adjustable shocks and coilovers are more than capable for the street and typically are used in race and track type builds and vehicles. Depending on your driving style, budget and what you’re looking to achieve from your vehicle’s suspension will determine what type of shock or coilover adjustment you will need for your car or truck. 

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