Shock Knowledge: Understanding How Your Shocks Work

Rick Sosebee
by Rick Sosebee
UTV Shocks
Shedding light on shock terminology and adjustment

How many times have you been in a conversation about ATVs or Side-by-Sides and the subject turns to very complicated suspension terminology? How about this for confusing; the conversation is actually about thermo-hydraulic dispersion of kinetic energy. Yeah, try that one on for size as a conversation starter.

I know when I first started studying my chassis and the suspension attached to it, I was baffled at some of the words I would hear thrown out like everyone should know what they meant. It was those very terms that would make my machine better or worse. If I could only comprehend what the heck everyone was talking about so I could use that knowledge to adjust my ATV’s suspension.

Well, it’s about time we lay down a dictionary of sorts to help anyone who might be going through the same things we’ve all experienced at one time or another. In this article, we hope to educate anyone needing to brush up on what these key words mean and help you understand the real potential of your machine by building your knowledge base.

Let’s first start with the types of adjustments and their particular names.

Spring Preload: Preload adjustment is essentially adjusting the pressure (or preload) on a shock’s spring. Most basic shocks will be preload adjustable only. This adjustment is made with either a threaded collar on the shock body with a locking ring that gives the best amount of adjustment or a five-way cam collar type that is limited to those five levels of adjustment. Turning the pressure up makes the ride stiffer and also raises the ride height of the machine. Taking preload out or loosening the preload on the springs will make the ride softer but can cause the suspension to bottom out easier.

Spring Preload Adjustment

This image from FOX shows how to adjust your preload with a threaded collar on top of the spring.

Compression Damping: This particular adjustment controls the movement of the shock’s shaft into the shock body. It controls how fast the shock shaft will compress. There are two types of compression adjusters, which will typically be an adjustment knob or slotted screw head. These adjusters control the flow of fluid in the shock. If your shocks are compressing too quickly and bottoming out, you’ll want to quicken up the flow of fluid. If your shocks are too stiff, you can slow the flow of fluid down. This adjustment is most popular on sport ATVs and UTVs for controlling the suspension when hitting jumps or whoops and even g-outs in the trails. You might even hear the talk of High and Low speed compression damping. This is attributed to features available on higher dollar shock systems. This means the damping capabilities are divided into low and high segments for finer adjustments. Individual adjusters will be available on the shocks where this is possible.

Kymco MXU Jump

This is about the time you’ll be hoping your compression is set stiff enough.

Rebound: This adjustment comes into play after you compress your suspension when hitting the bumps and jumps in the trail or on the track. Rebounding is when the shock spring is pushing the shock shaft back out of the shock body after it was compressed to return to its uncompressed state. This setting controls the speed of that rebound. This gives a more controlled return of the suspension once compressed and can help you maintain control of the quad or Side-by-Side. This adjuster will also be either a slotted screw adjuster or collar that spins around the base of the shock.

Shock Talk

Now that we have the adjustments out of the way, it’s time to clear up what some commonly used terms mean when speaking Shock Talk.

Ride Height: This is the height of the suspension measured at given points with a fully equipped rider with all of their gear.

Free Sag: This term refers to the machines amount of suspension sag under its own weight without a rider. This is also commonly referred to as static sag.

Yamaha YFZ450R Free Sag

Just the weight of the ATV itself will compress the suspension slightly. This is called free sag.

Rider Sag: This refers to the total amount of suspension travel is used when a fully equipped rider is sitting in their riding position on the machine. Typically this will be 30 percent of the total suspension travel.

Clicks: This simple term is in reference to the adjustments made on your shocks. Some shock adjusters click when turned and this has just stuck as the go-to adjective. Each notch of the adjuster is referred to as a click.

Bottoming: This is the action of compressing the shock completely and physically bottoming the shock. The spring is completely compressed, often resulting in a harsh feeling for the rider. This is where your compression adjustments come into play.

Kawasaki Teryx Bottoming Out

Here you see the front end of a Kawasaki Teryx bottoming out. It is not a pleasant feeling.

Pogoing or Bucking: These terms are used when the rebound is set too fast and the shocks, primarily rear shocks, are bouncing the rear suspension of the machine out of control.

Packing: The term packing is similar to bottoming, but in a more progressive manner. If your rebound is set too slow, the shocks will hit the first bump and begin to rebound. However, if the trail or track has many bumps in the same stretch close together, the shock may not have time to return (or rebound) fast enough to prepare for the next bump. The result is a packing effect as the shock begins to lose its damping ability and bottoms out.

Shock Types

Not all shocks are created equal and there are many different types of shocks to fit many different purposes and budgets.

Standard Non-adjustable: This is a gas-charged shock typically found on small youth machines or economical price point ATVs. There is no adjustment available.

Preload Adjustable: This shock is found on more entry-level sport machines or Utility quads and has only spring preload adjustability. This shock typically has a cam-style preload adjuster with five different stages of adjustment. Some may have a threaded body and preload adjustment ring instead of the cam adjuster.

Compression Adjustable: Very often found on the Sport machines, this type of shock will most likely have preload adjustability as well. This shock may come with or without a nitrogen canister on the side of the shock.

Adjustable King Shocks

You can see the compression adjustment knob on top of the piggyback canister of this King shock.

Compression and Rebound Adjustable: Offering the most possible adjustment, this type of shock will have a remote mounted reservoir or a piggyback nitrogen reservoir mounted on the shock. There will also be preload adjuster rings, compression and rebound knobs, and threaded slots. This gives the rider the most adjustment possible.

Air Shock: Performance air shocks have come a long way and the name FOX leads the charge. This shock has no spring or fluid and is actually controlled by air pressure. The tuning is a learning curve in itself, but once the basic idea and results are recorded the possibilities are limitless. You can reduce the overall weight of your machine and this will help the handling as well with less un-sprung weight in the corners.

FOX Float Evol

FOX is the king of air shocks. This FOX Float Evol allows an infinite level of adjustment.

Terms Within Shock Types

PiggyBack: This simply refers to the nitrogen charged reservoir that is attached or built into the back of the shock. This is common on most high performance Sport ATVs and on some Side-by-Sides.

Remote Reservoir: Some shock manufacturers offer shocks with remote nitrogen reservoirs that are connected to the shock body via a braided nitrogen gas line. This allows for mounting the reservoir in a remote location.

Can-Am DS 450

We hope this short guide will help you better understand the chatter when sitting in on the next bench racing session. Stay tuned for the next project where we’ll teach you how to adjust all of the suspension parts to make a better performing and more comfortable ride. Hopefully it will be a faster one as well.

Rick Sosebee
Rick Sosebee

Whether he is in Mexico covering the Baja 1000, building ATVs for local racers, or out enjoying the trails, Rick’s passion shows in his stories. Learning to wrench his own machines from his grandfather, Rick also has an undying appreciation for the mechanics of off-road vehicles. Do not let the dirt and mud fool you, though, as Rick also has a deep love for street cars.

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