I've read much about the superiority of IRS over solid axle on this board. IRS obviously has a smoother ride and soaks up the bumps and probably muds better then solid axle. However, I have noticed IRS seems to have trouble on off camber trails. There is some confusion over the term off camber but an example of it in my opinion would be riding on a trail that is horizontal on the side of a hill and not level but slanted severely. It does not matter if the off camber trail is rutted or a lot of bumps, only that it is off camber. One of our buddies had a SP 500 and would almost flip every time we went on this "off camber" trail to the point he did not like to go on it. I feel the IRS allows the side of the machine facing downhill to go lower to the ground thus causing a potential flip. This combined with IRS inherently higher ground clearance/ higher center of gravity. I personally like the solid axle in the stability it gives on the terrain I ride in. I have also ridden IRS machines and can see their virtues as well. Like I've said before, it's all tradeoffs. But if I was obsessed w/ a smooth ride I'd buy a cadillac and ride around on the roads.

 

JHAM,

Off chambers can mean many things to many people. Whatever interpretation you want to use is up to you. If you are looking for a set-up that will give the best ability to allow all 4 tires to touch the ground, simultaneously, over uneven terrain, IRS will offer the ability more so than a solid axle.

If your buddy's SP is leaning downhill so much, he might need to adjust his shocks/springs (if possible) to prevent excessive body roll.

Also, just because the ground clearance is higher, doesn't necessarily mean that the center of gravity is higher. If you are measuring the ground clearance at the center of the machine, the IRS should have greater clearance than an identical machine with a solid axle because the IRS suspension hinges "hang" the a-arms downwards to the sides to the tires. Conversely, with a solid axle, the hinge connects to a swing arm that leads downwards to the axle which is parallel to the tires, thus the closest point to the ground ends up being the end of your swing arm. Kind of hard to explain by using a keyboard....

There are payoffs to having either set-up, just a personal preferences. For me it's not so much about getting the smoothest ride, it's about getting the most traction.... I can also say that if I was interested in buying a Raptor or a DS and they had IRS options on them, I wouldn't opt for it.

 

sorry for the typo's...

 

I would love to have a DS with IRS. It would be the ultimate desert machine. Center of gravity has a lot to do with this. If you have a top heavy machine like any utility, IRS can encourage body roll. An anti-sway bar is a must. But Mark LoScerbo (StrongArm) has proven that a low profile IRS machine, like his LT-250 Suzuki, can excell with an IRS setup, without even using an anti-sway bar.
......One of these days IRS is going to come into its own in sport quads. At least in some areas like woods, trails and desert, maybe even MX. Swing arms and solid axles and carburators too for that matter, will hopefully go the way of the dinosaur. [img]i/expressions/face-icon-small-cool.gif[/img]

 

I agree that IRS gives better traction. However, IRS also lends to higher center of gravity. The center of gravity does not mean the amount of ground clearance but the height of the majority of weight in relation to top heavyness. Like you said, it's all rider preference. If you do a lot of mud and rocks, then IRS would be the way to go. If your on extreme mountain inclines and off camber type trails then solid axle is more stable, which is what we ride in.

 

Fourlix,

Interesting that you would want IRS on a DS, especially for desert riding - Why? Seriously?

If there is ever a time I would want a solid axle, it would be in a desert on a machine that hauls....

I can see how, on a low profile machines that have little suspension travel, you might be able to get away with IRS without many penalties. However, on suspensions that offer a lot of wheel travel, it could be a hairy ride to say the least. That is, unless you have a anti-sway bar on that offers very little "play" between the rear tires... ...but then, what's the use?

Anyway, anti-sway bars are not a must on utility machines. Some machines come without them straight from the factory and some owners, of the ones that do, take them off anyway. I took the sway bar off of my Griz, adjusted my preloads and it runs pisser....

 

Jham~

I'm going to respectfully disagree with you, and this isn't a "cut" on the Kodiak. I own an '02 Kod & an '02 Grizz and feel both machines are excellent. In off camber riding (side hilling by my definition) & rock climbing the Grizzly just feels better (with the listed mods below). I do see what you're alluding too, and it does makes sense.I hope you get to try a new Grizzly out....if you get one, take the anti sawy bar off, adjust your preloads, and put wider after market tires. I think you will be astonished.

We have this steep little side hill that we have to ride across now becuase of a new cyclone fence. We ride with solid axles that are swing axle, solid axles that are swing arm, and IRS. The most stable in the bunch were two machines: 660 Grizz & a SP700-both IRS. The least stable a Yamaha Beartracker - solid axle swing arm. Something else to consider, though, is quad width that also makes a huge difference on stability and essentially lowers your center of gravity the wide you are...if I'm not mistaken.

We're going riding this weekend, leaving today. Hopefully I'll be able to get some good pictures of this, although if it's snowed where we're going as much as it has here it may not be possible.

 

JHAM,

I'm not trying to get into a pissing fight here, but I have a perfect understanding of what Center of Gravity means. It's your statement below that I don't agree with.

"However, IRS also lends to higher center of gravity."

Why does IRS lend to a higher center of gravity? What weight is distributed higher on IRS than on a solid axle, by how many inches, and how much weight are we talking about?

I don't see a big con of IRS being that you have a higher center of gravity. Now, if you are comparing the Griz to the Prairie and you're talking about having a gas tank under your seat versus having it where most gas tanks are placed, then that's a different story....

 

Hey guys, look around. Independent suspension is on every fast machine out there from Formula and Indy racers to dune Buggies, HumVees and Stadium Ultralights. The Swingarm/solid axle setup we are all stuck with has two distinct advantages. It has zero body roll, and it is cheap to manufacture. The Manufacturers continue on this path because it works, it is cheap to make, and the buying public has misperceptions about Independent Rear Suspension that date back to Volkswagon swing axles. And the quad public thinks solid axles slide better.
The Swing arm/solid axle was simply a convenient way to make a quad out of a motorcycle. Utilities are starting to see IRS because Polaris led the way, applying 70 year old technology to the quad world with the Sportsman. Sports will be next.
....... Jaguar and Dusenberg had IRS in the 1930's. The physical advantages of lower unsprung weight, and having the shock/spring directly over the wheel hub instead of 18" over and to the left are enormous.
Ever Break an Axle? or simply bought a wider, stronger axle? The stresses are enormous, so are the axles. A-arms and half-shafts can be lighter than that single solid bar of steel. And getting all that weight above the springs means wheels can react quicker, follow the terrain more closely, maintaining traction and speed, with lower unsprung weight.
I do believe that an adjustable sway bar would be a must for a quad.
Dial in how much anti-roll you want. But even a very stiff anti-sway bar is not going to negate the advantages of IRS, lower unsprung weight and less stressed components. The "independent" part of it, one wheel going up while the other goes down, is only one part of the equation. Obviously that is not why Corvettes, Ferraris, Formula One racers, Porsches, etc. have IRS.
Imagine coming off a big jump, and getting sideways, landing on one rear wheel. Imagine the stresses going through that axle, carrier bearing, swing arm and finally to the shock/spring. Now imagine a sport quad with IRS doing the same thing. The shock/spring, right over the hub, absorb the impact and transfer the load to the frame, no sweat.
No Quad can jump and land like a dirtbike. But Stadium Ultralights, with IRS, can land huge jumps, and they weigh more than quads.
......In this arguement, Physics wins every time.
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I'm basing it mostly on the SP. I think it's pretty obvious that the higher the ground clearance, the higher the center of gravity, as I mentioned "a tradeoff". I do not have experience w/ the griz so maybe it would change my mind. I would prolly keep the sway bar on for that purpose though. The griz seat height is lower than the SP so maybe it is pretty stable on hillsides. I also agree that width helps in this aspect but would not want a very wide machine because the riding is so tight here.