PROJECT HONDA 400EX: New I-Shock suspension package and Rox Anti-Vibe Rizer bars

After last installing a set of new FullBore plastic, a ripping graphics kit, and a new seat, Our aging Honda 400EX was then put to an extended, long term test session. We thrashed on it for days on end. Then suddenly, it ended up all alone, sitting in the back corner of the mighty Dirt Wheels garage.
The problem? Sure, we loved the Honda’s rugged and easy-riding motor; heck, we even liked its stable handling manners. But, there were now so many hot new mid-sized sport machines (YFZs, KFXs, LTZs, and even Polaris Predators) that the EX soon found its way into the least often used part of our stable. After much neglect, we thought it time to dust it off, pull it out of storage, and made our Honda 400EX a Project Quad.

One area where the Honda 400EX could definitely use some help, especially on our older 2003 model, was in the suspension department. The stock shocks had seen their best days long ago and the overly narrow front end didn’t exactly fit well with our favored high speed riding antics. Our goal? To make the EX suspension and ride much more comfortable and able to handle an occasional race.

You even get a DVD inside each box on how to install the I-Shock kit. Talk about complete packages.

To do that, we picked a new player in the suspension and A-arm market. HydroDynamics USA has come out with a line of ATV front suspension kits called I-Shocks. They sell these as a complete kit, including upper and lower A-arms, bushings, tie rods, steel brake lines and clamps, and even the shocks themselves. They are so confident of the quality that they offer a full lifetime warranty on the final product.

The I-Shock front suspension kit comes complete with everything you see here as well as their new piggyback reservoir shocks.

 We picked up one of I-Shocks’ new suspension kits for our 400EX’s front end. The suggested retail price for the Honda 400EX kit is $1850. While that might sound like a lot of money, you do get the complete kit with shocks and everything needed to install it. You will not have to piece together all the parts you would need to build a similar kit, such as shocks ($1000-$1500), wider A-arms ($400-$700), and new brake lines ($100-$200). Once you figure in prices for separate shocks, separate A-arms, replacement brake lines and clamps, then all of sudden you appreciate the I-Shock kit’s value.

To get a better idea of what the I-Shock technicians are looking to do with their new suspension kits, we spoke with company president Darren McGarvie.
“We have taken a very logical and scientific approach to suspension which is why some of the components you see may look different than some models produced by other manufacturers,” said Darren.
“Suspension should not be a ‘black art’ or difficult for the average enthusiast to grasp. I think our customers will come to appreciate our ‘suspension made simple’ concept. A common question we get with most aftermarket A-arms and shocks is… ‘Will these shocks work with that arm?’ or ‘Where do I find brake lines for my new front end?’ ”
“With our new complete front end package kits, we have assembled what we consider to be the very best suspension products in the world, all in one easy to install kit. It includes everything from shocks and A-arms to specialty tools and an instructional DVD.”

I-Shock imports their front shocks from Italy and then sets them up to suit the various A-arm kits they sell.

“Let me explain some of our design characteristics and at the same time perhaps dispel a few myths,” added McGarvie. “First, the term ‘long travel arms.’ This popular design incorporates the use of a ‘long shock.’ However, this does not mean that the front suspension will necessarily have more travel. If your ATV frame hits the ground when bottoming, you are probably at max travel already. What good is 14 inches of travel when four inches of it is underground?
“The motion ratio or leverage ratio can be, and often is, manipulated to offer better performance. The leverage ratio is the relationship of the wheel movement versus shock shaft movement, a critical factor in suspension design. Also, the long shock design usually incorporates a larger shock which contains more oil. More oil means less oil contamination issues and better heat dissipation.
“However, can technology offer us solutions to these problems without the use of heavy and expensive ‘long shock’ front ends? Absolutely. What I believe is most important here is not the motion ratio or leverage ratio, but rather the leverage ratio curve. The leverage ratio curve, commonly referred to as the wheel force curve, indicates the progression of force that is required to move the tire through the entire span of travel. Basically, you want your front end to get stiffer before it bottoms right? The problem is, a linear leverage ratio curve, as found stock on most ATVs, will offer little bottoming resistance unless the shock is valved and/or sprung abnormally stiff. Unfortunately, this stiff shock will be harsh on smaller bumps.
“So, how do you get the suspension plush on top, firm on bottom? Run a larger percentage leverage ratio curve. This has everything to do with the geometry of the suspension components and can be accomplished without a ‘long shock’ as we have proven through data acquisition. This process takes care of the progression in both valving and spring.

“If that’s not enough for you, what about A-arms with the bent or ‘gull wing’ look? Some claim a plusher ride! Unless my schooling has failed me, the tubes on A-arms could do loops from one end to the other and as long as the pivot tubes, shock mount location, and the ball joint boss are all in the exact same position, you will have the exact same geometry—period!” claims McGarvie.
“What about strength issues? I personally believe a straight tube is stronger than a pre-bent one. And ground clearance? I think the closer to the ground the arms are, the less ground clearance you have.”

“Okay, let’s talk about +1 forward A-arms. Listen people, bigger is not always better! A-arm manufacturing 101 says to first find the CG (center of gravity) of the machine. Check the squat and dive characteristics of the machine, which include chain forces, calculate weight transfer, and then, only then, make a logical, calculated decision based on sound engineering principles confirmed by rider input.
“We have found only one model of ATV that actually had improved performance with the tires moved forward. This is the Yamaha Banshee. Guess what, our Banshee arms are +1 forward. Try this little maneuver with the Honda TRX 450 and you would find yourself looped out right off the gate! If you see a manufacture with a complete line of +1 forward arms—ask them why?
“My goal is to help you the consumer understand that suspension is not a ‘black art’ but a science of common sense. Most suspension guys don’t want you to know how simple suspension really is; we do. We make suspension simple.”

After our suspension primer from Darren, we were eager to tackle the 400EX’s front end. The I-Shock kit comes with a check list of the parts included inside it. The A-arms are built of chromoly tubing and consist of upper and lower units with pivot bushings, sleeves, zerk fittings, and ball joints pre-installed in all four arms. It also comes with two tie rods, and four brake line clamps with steel braided brake lines. They include a ball joint press tool to get your stock ball joints loose and a shock spring pre-load tool for adjusting the piggyback reservoir shocks. The shocks themselves come with adjustable compression, rebound and preload settings. While the shocks are built in Italy, I-Shock imports the bodies and springs and sets them up to their own internal specs. They also offer a rear shock rebuild service, which costs around $50-$60 and includes new oil, nitrogen and seals.
The toughest part was removing the stock ball joints (with the supplied tool) and replacing them with the new units included in the kit. From start to finish it took us a reasonable two hours to replace the entire front end on our 400EX and bleed out the brake lines (the most time-consuming operation of the installation.)
Once we had dialed in the ride height and aligned the front end of the machine and set the toe-in/toe-out, (explained clearly in the printed instructions and on the included DVD video), we bolted on the new I-Shocks and were ready to try the machine out.

To complete our Project, we opted to install a set of Rox Pivoting Anti-vibe Risers so that we would have a much wider choice of bends and heights than the EX’s stock handlebars. The Rox Anti-vibe Risers allow you to put on the much less tiring “Fatty” handlebars that help take out some of the vibration you get through the stockers. They offer a similar effect to what you might get by installing an aftermarket steering stem on your machine.
It was a simple matter to bolt the new Risers on and then clamp on the new, fatter handlebars. Rox makes a complete line of Risers for almost any type sport or even utility quad application. They sell for $149.95 for the Anti-vibe Risers, with the “Fatty” bars going for an additional $69.95.

Landings were much smoother on the EX with our new I-Shock front suspension package installed.

When we took our newly widened Honda 400EX out for a test spin, we immediately noticed the much more stable ride, especially through rough, whooped-out terrain. Where we had our hands full on the stock width front end, and stock, worn out suspension, the new I-Shock equipped EX had a much superior ride through this type of terrain.
It sucked up the bumps and meanest pot holes that had previously jarred our test riders hands off the bars. Speaking of bars, the new Rox Pivoting Anti-Vibe Risers and Fatty handlebars were a great addition as well, especially when the going gets rough. They significantly cut down on vibration and offer a much more comfortable and ergonomic position when riding aggressively.

Overall, we liked the ease of installation, much improved handling and plusher riding front end we got with the I-Shock front suspension kit and Rox Pivoting Anti-Vibe Risers and Fatty handlebars. They raised the comfort level of the 400EX up quite a bit, and now it’s getting much more track and trail time, instead of gathering dust in our garage. For more information, contact I-Shock at (866) GO Shock or e-mail them at For more on the Rox Anti-Vibe Pivoting Risers contact them at (218) 326-1794 or roxspeedfx.­com.

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