Yeap, it's true!
I bet that got your attention, eh? Well, now let me jab you one more time! The only reason IRS is so popular is because consumers like you(!) demanded IRS because they(you!) thought Independent Rear Suspension systems were better. Huh? You bought ATVs with IRS rather than swingarms so manufacturer’s all needed to make ATVs with IRS so you would be competitive and you would also buy their’s!
Now let me explain myself. First of all there are no utility ATVs or UTVs than have optimized swingarm suspensions to use as a comparison, whereas IRS systems have undergone several years of improvement.
Now let’s also look at the fact that most IRS systems have huge sway bars that restrict the ‘actual’ independent travel of each of the rear wheels tremendously. Don’t believe me? Go out to your garage and put a jack under one rear wheel and jack it up. (Yeah I know that will require that you first jack up the ATV to get the wheels off of the ground so that you can then put a jack under just one of the tires. And yes I know you may need to sit on the ATV to put some weight on it to ‘try’ to make it move. And yes that might just be another problem here). So, did you do it? Then you know that there was little or no movement. Amazed? I know, it’s an amazing thing. If one rear wheel goes up, the other does too. It’s only independent depending on what you think ‘independant’ means – if you know what I mean….
So why is this so? Because completely independent rear suspension travel does not work on an ATV! If you disconnected the anti-sway bar you’d find that the high center of gravity of an ATV would cause the independent travel of the rear wheels to be a horrific problem, causing the ATV to lean tremendously in the corners, and fall over every time the terrain was uneven.
Let me explain a bit further. If you have one end of a vehicle with the wheels working independently of each other, the other end of the vehicle needs to be an anchor to keep the machine’s wheels below the rest of the machine (in other words it’ll fall over!) Hence a stable rear suspension system that can either be dual a-arms with a swaybar connecting them together, or a swingarm system with a solid rear axle.
Need some examples? How about racing ATVs. Or the ultimate off-road speedster, the ‘Trophy Truck’. Now if you checked out trophy truck suspensions you probably noticed that they are a unique blend of individual trailing arms with a solid rear axle. Arctic Cat had a very similar system many years ago that worked incredibly but was not accepted by consumers so AC switched to what was demanded – an IRS system with tons of ground clearance! And you guessed it, you lost again ;-)
You see, you need the stability of a solid rear axle for the ultimate in stability and handling. But don’t think that just because it’s a swingarm that it can’t have great travel. (refer once again to the comment regarding sport quads and trophy trucks). Why not set up a swingarm rear suspension on a Prairie or Rubicon with 12” of wheel travel? They do it on the sport quads and the trophy trucks…..Oh yeah, I said that already ;-)
So I contend that consumer demand for independent rear suspension systems have made ATVs handle worse than if we would have spent the time to develop better, longer-travel swingarms on our utility ATVs (and UTVs!)
Do I doubt my comment? No, I just got back from riding my tricked-out, Elka-equipped, Kawasaki KFX 700. And if I need more proof I’ll take a spin on the project Raptor…