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HOW-TO: Setting up UTV suspension

March 2, 2017
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Most ATV and UTV suspensions are really pretty similar. Whether it be race or play, swingarm, A-arm or crazy long-travel trailing arms, they are pretty much all controlled by some type of coil-over shock absorber. While many of the newer performance models might have multiple adjustment options, even the most basic utility options will have some sort of adjustment. The factory setup is designed to “perform” for a very wide range of users and conditions; this set “factory” setup is not going to be ideal for you end users, just good enough to keep everything safe and manageable. Six types of external adjustment can be found on ATV or UTV shocks. Some of the more basic models might only be preload adjustable, but even just individualizing this one setup for you will make a difference. The six available adjustments are low and high-speed compression damping, rebound damping, preload adjustment, ride height adjustment, and crossover adjustment for dual-rate springs or higher. There is also the option of going to stiffer (or softer) straightrate, progressive-rate or dual-rate springs to dial the ride for your needs, weight and riding style or all-out racing.

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PRELOAD ADJUSTMENT FOR RIDE HEIGHT
This is the most common adjustment and found on nearly every ATV or UTV shock. Preload adjustment is also a very basic way of adding compression, as more spring pressure will stiffen your suspension and less will give you a smoother ride. Increasing preload also means increasing ride height, which will also affect your handling. A threaded preload adjustment features a threaded shock body and dual-locking rings that are threaded down the body against the spring to apply pressure, essentially loading the spring. You will typically need a hammer and punch if you don’t have the special spanner wrench.

The even more basic preload adjuster is a collar with multiple slots in which turning it applies more pressure on the spring. This collar setup usually only offers around five preload settings, where the threaded setup is pretty much infinitely adjustable. Proper race sag is also achieved by proper preload adjustment. On an ATV or dirt bike, for that matter, a single-spring rear shock should have 30 percent of its total travel used in sag. Sag is measured as the difference between unloaded suspension and then with the rider sitting on it. For example, a typical ATV with 10 inches of travel should have about 3 inches of sag. Sag is often referred to as the first and most important suspension setting you should make on a sport quad or dirt bike. CanAm adjusted preload on its DS450s at the factory to 7.5 inches of ride height with a 175-pound rider aboard, so heavier riders will have to add preload and lighter ones will lower it.

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COMPRESSION ADJUSTMENT(S)
Low-speed compression is the most commonly found compression adjustment on OEM shocks, but some higher-end sport models and many aftermarket shocks will feature highspeed compression adjustability as well. Compression, in general, is the damping that helps prevent the shock from bottoming. Too much compression will make your ride harsh, but if you’re using all of your suspension travel, you need to add in some compression damping. The low-speed compression adjustment helps with braking bumps, small jumps and G-outs, but high-speed compression is usually the culprit if you’re bottoming off of big jumps. The compression adjuster is usually a knob or screw, and it’s always found on the body or reservoir of the shock. For most shocks, this compression knob is turning in a needle valve that regulates oil flow. You don’t want to ride with the needle valve buried all the way in, as it creates more shock heat and can even break the shock shaft. If your proper setup is within the last two clicks on compression, then you need to have compression increased internally with a shock re-valve and/or go to stiffer springs (but that affects rebound damping). Externally adjustable high-speed compression is found on many highend aftermarket shocks and a few sport models like Yamaha’s YFZ450R and Raptor 700R. High-speed compression controls bottoming off large jumps or bigger hits and also help with body roll. If you have too much high-speed compression, it is often more noticeable with a harsher, more abrupt ride in medium-sized terrain.

REBOUND ADJUSTMENT
Rebound adjustment controls the speed at which your shock returns to the extended or “up” position. Adding rebound damping essentially slows your shock’s return speed, while taking out rebound or “speeding” it up will make it come back to the extended position faster. The rebound adjuster is located on the bottom of the shock and is usually a screw, but can also be a knob located at the bottom of the shaft. Rebound adjustment has been on the rear end of most sport ATVs for years, but just recently made its way to the OEM front shocks on a few select performance models.

Rebound adjustment is often overlooked or misunderstood, but it isn’t rocket science and can really play a big part in the proper handling of your ATV/ UTV. If rebound is too slow, your suspension can “pack” in the whoops. This happens when the shock can’t fully extend before getting smacked by the next whoop or bump. After a handful of successive bumps, you will effectively have little to no suspension travel left. This “packing” can make your machine swap uncontrollably in the whoops. On the opposite side of this adjustment, a shock with the rebound that’s too fast will try and kick you as you leave the face of jumps or even whoops.

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CROSSOVER ADJUSTMENT
A multi-spring setup gives the shock a more progressive spring rate. Your larger “main” spring is your stiffest, and the smaller springs will be progressively lighter. Crossover spacers are the washers between the springs that keep everything from collapsing in on itself. Multiple crossover spacer rings or a threaded crossover setup can be used to adjust where/when during the shock travel that the load switches to the next stiffer spring. Polaris RZR XP 1000s have true dual-rate springs but no crossover rings, and the Fox Edition has its rear 3.0 top springs almost coilbound, so as good as the Fox LE rides, crossover rings and longer top springs, like those from Walker Evans Racing and Shock Therapy, improve the ride greatly.

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OPTIONS GALORE
If you have an ATV or UTV, there are options from the aftermarket to make it handle better. That super-basic oil-emulsion shock on your 4X4 might not be that trick, but the sky’s the limit when companies like Elka Suspension offer everything from a basic custom valved coil-over to a fully adjustable Stage 5 shock for almost any ATV/ UTV in existence. The inside of a basic emulsion shock is just a plunger and oil/nitrogen; the oil tends to froth or cavitate, and they overheat easily, compromising the dexterity of the oil and the end performance of the shock. Just upgrading to the most basic HPG (high pressure gas) shock can offer huge performance gains with the right valving.

The HPG shock uses a piston with seals or O-rings to separate the oil from the nitrogen, and often features much tricker and intricate valving—compression and rebound shim stacks. Almost all current sport/performance quads and performance UTVs are now equipped with HPG shocks from the factory. If you remember the basic front shocks on a TRX250R or even the early 400 EX and LTZ400, then you know it hasn’t always been this way. Another huge benefit of OEM supplied HPG shocks is that they can be rebuilt and even re-valved by a shock technician for impressive results. Today, a typical re-valve and re-spring on your stock shocks can be almost as good as most aftermarket shocks and will cost you less than a quarter of the price. The stock springs on most shocks are a progressive-rate single spring, while some more basic offerings are straight rate. This progressive rate means the spring is wound tighter at one end to offer changing tension as it is compressed through the shock’s stroke. A popular upgrade from the aftermarket is to ditch the stock spring in favor of a dual- or triple-rate setup that can offer a more fine-tuned spring rate.

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SHOCK THERAPY FOR YOUR RZR
The Polaris RZR XP 1000 is currently one of the best-selling UTVs in the world. The 18 inches of suspension offers an incredible ride through the desert, but, like all other stock setups, it is designed to perform under the max allowable load for the machine. This over-valving makes for a rougher ride than necessary, especially when hitting slower-speed stuff and small chop. The guys at Shock Therapy have spent countless hours developing valving, spring rates, and other mods to improve and personalize your stock XP1K shocks.

The RIS, or Ride Improvement System, is designed to cure any and all harshness felt at the seat, allowing for true all-day ride comfort. They offer four progressively better and more involved packages, but the basic Stage 1 kit will surely impress even the pickiest of driver or passenger. The Stage 1 kit smooths out the ride and makes the XP more stable at the same time.

Shock Therapy modifies the stock piston and changes the valving for increased flow to the compression adjuster. They also machine the stock shaft to prevent bottoming in G-outs. The valving also cures most of the rear bucking associated with the stock setup. ST also adds secondary rate collars to the front shocks to take advantage of the dual-rate spring that doesn’t really get used in the stock configuration.

This Stage 1 kit drastically improves comfort in rough terrain, as well as really improve overall handling. The Fox Edition with Internal By-Pass shocks (IBP) adds another element for adjustment, but goes beyond a standard XP1K in not needing a Stage 1 RIS kit (valving and front crossovers) or Stage 2. Stage 2 is a 50-percent-stiffer rear torsion bar with adjustable mounts and frame stiffener, plus Stage 1 mods. Stage 3 adds Dual-Rate Springs (DRS) on all four shocks with crossovers, and Shock Therapy has proprietary springs made, even for the Fox Edition, and their springs cost less than Eibach’s. Stage 4 adds a new front torsion bar, and Shock Therapy is developing one for the Fox Edition that has four-link mounting points for more adjustment. They also have several stages of kits for Wildcats, Mavericks, Commanders and Rhinos.

 

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