Suspension Upgrade for Honda TRX450R

Dec. 28, 2005 By James Graham


Although the stock suspension on the Honda TRX450R is very good for OEM, there is always something better. We set out to see if we could improve on the suspension and ride quality and we think it worked out very well. Addition of new Ohlins shocks, American Star Manufacturing a-arms and Speedtrap Motorsports rear wheel spacers made a great improvement. Coupled with the new Trail Tech handlebars and billet mount, the 450R feels like a totally different quad to ride. Handling is much better over the stock components. The shocks soak up the jumps, and the wider stance makes the quad more stable and easier to handle the corners. One of the complaints was with the stock radial tires it was hard to get the quad to slide around the turns, now with the quad being wider this is accomplished much easier.

When we contacted American Star Manufacturing for a set of 2”extened a-arms they were still in the process of finalizing the new a-arms. We had to wait a couple of months to receive them, but they were worth the wait time, and we were able to order them powder coated black to match the all black 450R. American Star holds the patent for the heim joint that several of the major a-arm builders use. It is very good design and has less friction than the ball joint type.


Installation is pretty straight forward and all the necessary parts are included for a easy install. First we laid out all the parts and sorted them out for left and right configuration. We blocked up the front end and began the installation. After removing the wheels and tires we disconnected the brake lines and removed them. (More on the brake lines later). After removing the shocks the next step was to remove the spindles. Since they are a taper fit they can sometimes be a little hard to remove. I good quality tie rod fork makes this job much easier. Loosen the mounting nut, and couple of good hits with a hammer and the joint should pop loose out of the spindle. Be careful to not tear the rubber boot with the fork. Remove the a-arm bolts, but keep them as they will be used to mount the new arms. Now reversing the procedure we install the new a-arms back on to the frame, then remount the spindle. The procedure is the same for both sides. Do not tighten the heim joints at this time.


Now is the time to reinstall the wheels and check your alignment. The a-arms are fully adjustable for camber and caster so you will be able to set them for your personal preference. If you need to adjust on the camber you will need to remove the heim joint from the spindle to be able to turn the joint in the proper direction. Once you have the camber set where you want it, then it’s recommended to use Locktite on the joints and tighten them to the proper torque setting. The proper caster can be set by moving the inside joints on the upper a-arms in or out to get the setting where you want it. The more caster the more the quad wants to return to the straight ahead position. Too much caster makes steering more difficult.


Since the a-arms are two inches wider than stock, the original brake lines are too short, so we opted to use a new set of braided lines from American Star. These also come with some really trick looking clamps to secure the lines to the a-arms. We believe bleeding the brakes is the most difficult part of replacing the a-arms and brake lines. Once trick we have learned to bleed the brakes is to force the fluid from the brake caliper back into the brake reservoir. We do this with a larger syringe and a piece of silicone tubing. First remover the master cylinder cover and remove a little bit of the brake fluid, you don’t want it to run over. Fill the syringe with brake fluid and make sure you have all the air out. Slip the tubing over the brake bleeder valve on the caliper and then open the bleeder about a half turn. Begin forcing the brake fluid back into the caliper and watch for air bubbles coming out in the master cylinder. Continue adding fluid to the caliper until you do not see any more air bubbles. Repeat for other side. Make sure you don’t over fill the master cylinder, remove brake fluid as necessary. When you cannot see any more bubbles, close up the bleeders and replace the master cylinder cover. Check your brakes, but you should be good to go from there.


We have been very pleased with the American Star Manufacturing a-arms. They are will made and nice looking. The powder coating is hold up very well even with running through lots of weedy trails. The added width has really improved the handling of the 450R. American Star makes a-arms kits for nearly any rider, be them racer, recreational or anywhere in between.

Looking for shocks we decided to call up Ohlins and get their latest shocks for the 450R. The shocks were set up for the 2” extended a-arms we had coming from American Star Manufacturing and all three came with “piggyback” style reservoirs. We know the racers all use the remote reservoir type shocks, but we did not feel these were needed for our application. The main advantage of the remote reservoirs is the addition of more oil and the ability to get the reservoir where more air flows over it for cooling. In racing situations, this is very important as you don’t want the oil to get hot and the shocks to stop working to their full capacity. Since we don’t race and only ride for recreation, the added expense of the remote reservoirs was not justifiable.


The shocks were a direct replacement for the OEM shocks and were very easy to install. We used a floor jack and raised the front end of the quad until the stock shocks were in a neutral position. Then it was just a matter of removing the top and bottom bolts and replacing the OEM shock with the new Ohlins shock. The rear shock was changed out much in the same way, raised the frame of the quad until there was no load on the rear shock and removed the top and bottom bolt, then replaced the shock with the new Ohlins rear shock. The yellow springs on the new shocks really look good with the all black plastic on the 450R.


There are three adjustments on the shocks, spring pre-load, compression damping, and rebound damping. Ohlins sets up the shocks according to your preference using rider weight, type of riding, and rider experience. The settings on our shocks were very close and we only tweaked the settings a little to get them to work the way we liked. We rode the quad on trails and around the MX track to get a feel of how the shocks were working, and then made minor adjustments one at a time to set them up the way we wanted. It’s very important to only adjust one setting at a time so you know which setting helped and which setting needs some more work. If you adjust two things or three things at a time, you don’t know which one is helping or hurting your ride quality. This does take some time and effort to get things right, but well worth it in the long run. A good setup on the shocks makes a lot of difference in the way the quad handles and rides so take your time and make sure you get it the way you like.


Preload: This is the first thing you need to set on your new shocks. This sets the height of the quad when the rider is sitting on it. Your shocks should come with a chart to give you the measurements you will need. Basically you measure the height of the quad sitting with no rider, then measure again with the riding in position. The difference in height should fall within the recommended range. Your shocks will come with a spanner wrench to do the adjusting, please don’t use pliers as you can damage the nut used for adjustment.


Damping, Rebound: This setting affects the characteristics of the quad the most of all the settings. The setting knob is located at the bottom of the piston rod and can be adjusted in 40 steps. If your quad feels loose and bouncy the rebound needs increasing. Turn the adjustment know about 4 clicks clockwise and try again. If it gets hard and bumpy turn the adjustment counter-clockwise. Keep making adjustments until if feels just right.


Damping, Compression: The compression is set with a knob or screw on the top of the external reservoir. Our set has both low and high speed settings so it comes with a large nut and a slot headed screw. The high speed adjuster has a wide range within 4 turns, and the low speed has 25 steps. If you quad feels soft and maybe bottoms out in the jumps the compression needs to be increased. If it feels harsh the compression needs to be reduced. Adjustments are made by turning the nut or screw clockwise to increase or counter-clockwise to decrease. The large nut is the adjustment for high speed and the slotted screw inside the large nut is for low speed. Make small adjustments until you feel the settings are where you want them to be. Always begin adjustments at the recommended setting and work from there.


Shocks are one of the more expensive upgrades for your quad, but we feel its one of the best upgrades you can do. After all, more speed will not do you any good if the quad does not handle properly to begin with. Your quad will handle better and you can run faster with a good setup on the suspension, and then worry about engine upgrades for more power. A full set of shocks front and rear will run anywhere from $1,000 up to $2,000 depending on brand and options. We have been very pleased with the Ohlins.


After installing the +2 a-arms we needed to widen the rear end of the quad to kinda balance things out. Here we opted to go a cheaper route and use axle extenders instead of replacing the rear axle. Gary Gauger of Speedtrap Motorsports sent us a set of their new axle extenders to try out. The extenders are machined from one solid piece of metal and all you have to do is screw them onto the existing axle bolts and then bolt your wheels back in place. Very simple and very easy to install. They are not recommended for racing applications, but for our sport recreational riding they work great, and we have had not had any problems at all. The extenders add total width of 3” overall and balanced the quad out real nice.

For product information check out

American Star Manufacturing


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