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TECH: BASIC SUSPENSION SETUP SECRETS

June 10, 2017
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— Walker Evans’ pros tell all — By the staff of Dirt Wheels with Reid Nordin.

 

Having your UTV set at the correct ride height will help the handling, suspension action and the suspension articulation, in addition to maximizing the available ground clearance.
Having your UTV set at the correct ride height will help the handling, suspension action and the suspension articulation, in addition to maximizing the available ground clearance.

 

Recently, we had a unique opportunity to work with UTV suspension. Two friends have identical 2012 RZR 800 S models. These cars are basically clones of each other with almost identical aftermarket parts installed. Both had added between 100 and 200 pounds of popular additions to the stock machines. On the other hand, both had stock and original suspension. Not even the preload setting had moved from the factory. Both cars had 2500 miles and were on the original tires and CVT belts. When we were driving behind them, the cars didn’t look like they had much travel. We spent a little time adjusting the preload on one car, then let the owners try both cars back to back over a small loop. Both were embarrassed at how much performance they had ignored by not checking the most basic suspension settings.

 

Each family or brand of machine has a specific ride-height measurement to shoot for. Most of the Polaris XP 1000 or Turbo machines should be pretty close to the measurements we used—13 3/4 inches front and 13 1/4 inches in the rear with stock tires. Taller tires add to that number, so know how tall your tires are. In the front you measure from the lower rear A-arm mount.
Each family or brand of machine has a specific ride-height measurement to shoot for. Most of the Polaris XP 1000 or Turbo machines should be pretty close to the measurements we used—13 3/4 inches front and 13 1/4 inches in the rear with stock tires. Taller tires add to that number, so know how tall your tires are. In the front you measure from the lower rear A-arm mount.

 

WHAT PROS SAY

After our experience with these cars, we decided to see what pros had to say about setup. We contacted Reid Nordin at Walker Evans Racing (WER). Nordin has the credentials for the job. He has been a specialist at Walker Evans Racing (walkerevansracing.com) for several years, but he has 30 years’ experience at Kawasaki starting as a pro three-wheeler race mechanic for Jimmy White. During his time at Kawasaki, he was involved in testing most of Kawasaki’s off-road products.

 

At the rear of the XP line are open frame tubes that face down just below the radius-rod mounts. Use that point to measure to the ground in the rear. The rear is the most likely to be off if you are carrying anything in the bed or using a spare-tire mount.
At the rear of the XP line are open frame tubes that face down just below the radius-rod mounts. Use that point to measure to the ground in the rear. The rear is the most likely to be off if you are carrying anything in the bed or using a spare-tire mount.

 

You will want to work on a flat surface when adjusting suspension, so we met up with Nordin in the desert. He spread a tarp on a flat section of terrain, but he says that you can check these settings in the driveway before you load up or even on the deck of your trailer. Before you start, make sure that all four tires are set to your normal pressure. You will need a tape measure, a floor jack to lift the car and the proper tools to move the preload rings on the shocks. You won’t be lifting the car much—just enough to take the weight off the suspension, so as soon as you see light under the wheels, you are good to make adjustments.

 

For A-arm cars, the A-arms should not be straight. They, too, should have a downward angle when the car is sitting, especially if there are no passengers in the machine.
For A-arm cars, the A-arms should not be straight. They, too, should have a downward angle when the car is sitting, especially if there are no passengers in the machine.

 

GETTING STARTED

Begin with the car ready to roll with everything you normally carry. It is a good idea to have the fuel tank near full as well. We started with a 2017 Polaris RZR XP 1000 with the Ride Command option and 30-inch Tusk Terrabite tires installed. The basis of all UTV suspension settings is ride height. You find your car’s ride height by measuring from a chosen point at each end of the machine to the ground. On a RZR XP-series machine, WER measures from the rear A-arm mount bracket in the front to the ground. In the rear there are two open-frame tubes near the radius-rod mounts. Measure from the open edge of the tube to the ground.

 

Walker Evans Racing’s Reid Nordin says a quick-and-dirty check is inspecting the radius rods. They should have a slight downhill angle on the lower ones. If those rods are straight, then the ride height is way off.
Walker Evans Racing’s Reid Nordin says a quick-and-dirty check is inspecting the radius rods. They should have a slight downhill angle on the lower ones. If those rods are straight, then the ride height is way off.

 

What should the measurement be? Nordin explained that most machines are delivered at the correct ride height, so the job is to keep the machine at that height. So, if you have a new machine, pick a spot and measure the ride height when the car is stock without any aftermarket parts that add weight. WER has ride heights for most popular machines. Any of the sales staff at (888)-WE-RACE should have the numbers you need For the stock XP, the ride height should be 13 3/4 inches in the front and 13 1/4 inches in the rear. Since our machine had 30-inch tires in place of the stock 29-inch tires, we were looking for 14 3/4 front and 14 1/4 inches in the rear. Once you have the ride height for your machine set, measure how tall the stock tires are so you will know how much new or different tires affect the ride height.

 

Coil binding is when all of the coils touch. That basically turns the spring into solid steel. If that happens, you will limit the machine’s travel and put excess load into the chassis. Coil binding leaves marks like these on top of the coils. This is a sure sign that you need a stiffer or longer spring
Coil binding is when all of the coils touch. That basically turns the spring into solid steel. If that happens, you will limit the machine’s travel and put excess load into the chassis. Coil binding leaves marks like these on top of the coils. This is a sure sign that you need a stiffer or longer spring

 

WATCH WEIGHT

In our earlier example with the RZR 800 S models, the owners had added weight, but the spring will also sack out over time. For those cars, the ride height was over 2 inches too low, and we weren’t surprised by that. Our XP 1000 is all stock except for the tires, and it has only 300 miles on it. The ride height was a half-inch low at both ends after 300 miles. Use a tape measure to find the distance from the preload ring to the top of the shock. Walker Evans Racing shocks use a single preload ring (no lock ring) with holes around the circumference to insert a tool in. After jacking the machine up, Nordin was able to spin the shock spring by hand. Make sure that the preload ring is turning with the spring and that you are tightening it, making the spring length shorter. Other brands of shocks have both a threaded preload ring and a locking ring with slots to use a shock spanner for adjustment. You will need to use a shock spanner (probably in the stock toolkit), or a hammer and punch to loosen the lock ring. If you don’t jack the car up, moving the preload rings will be a bear.

 

Reid Nordin adjusts customer suspension constantly, so he cut a Harbor Freight Tools round-shank screwdriver to use as an adjusting tool. On some machines with limited access to the spring preload adjusters, it may be easiest to simply remove the shock to adjust the spring preload.
Reid Nordin adjusts customer suspension constantly, so he cut a Harbor Freight Tools round-shank screwdriver to use as an adjusting tool. On some machines with limited access to the spring preload adjusters, it may be easiest to simply remove the shock to adjust the spring preload.

 

EASY ADJUST

Our relatively new machine adjusted easily by hand. Our four-year-old RZR 800s needed penetrating lubricant on the threads and assist from a shock spanner to change the preload on the springs. To get our XP adjusted took relatively small adjustments, but the RZR 800s took an inch of added preload. There is no hard-and-fast measurement of how much preload increase is too much, but all Polaris RZR (and General) manuals caution against adding more than 1 inch of added preload over stock. That much preload is a sign that you need new and/or stiffer springs for your machine. Certainly, if the springs are coil-binding, meaning that the spring coils collapse together before the shock utilizes full travel, then you are wasting travel and probably overtaxing the rebound damping as well.

 

Before you start adjusting the preload, measure the threaded area above the spring. Make sure that both shocks have the same preload, and then measure the change to make it easier to do to the other side. Some mechanics simply count the turns they make. Marking the preload ring with a marker will help you count the turns accurately.
Before you start adjusting the preload, measure the threaded area above the spring. Make sure that both shocks have the same preload, and then measure the change to make it easier to do to the other side. Some mechanics simply count the turns they make. Marking the preload ring with a marker will help you count the turns accurately.

 

METAL FATIGUE

A spring does a lot of work, and it does fatigue over time and use. If you use your machine hard in the rough, you should have the shocks serviced every 1500 miles, and WER recommends new springs at that time for best performance. A shock service includes new seals, piston-wear bands, oil and nitrogen. Prices quoted for shock rebuilds are generally for labor only, so parts and suspension fluid are an additional cost.

Once you have adjusted the preload, start the car and drive it about 30 feet, turning the front wheels lock to lock along the way to reset the suspension. Pull the car back to the same spot and check the ride height again. Make any adjustments that are needed.

 

Other brands of shocks will most likely have a preload ring and a locking ring. You will need to loosen the locking ring before the preload ring can be moved.
Other brands of shocks will most likely have a preload ring and a locking ring. You will need to loosen the locking ring before the preload ring can be moved.

 

Before we started our work we selected a test loop, locked in the GPS track with the Ride Command and drove it enough to get a feel for the car. After the ride height was set, just that half-inch of difference made a nice improvement in handling and chassis balance. The rear in particular had a less floppy feel. Once you have more experience with suspension adjustments, you may find you prefer a setting that is slightly different than the standard ride height. Desert cars might go a little higher for increased ground clearance, and cars used on smoother terrain with many turns might use a setting slightly lower. One thing is certain—far too many people treat suspension as a set-and-forget item, and that can seriously compromise the handling and ultimate performance of the machine.

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