This makes no sense, the suspension can't articulate better in the rear with the ACT because the axle is one solid peice, so for rough terrain it is useless when compared to the IRS as the rear wheels will track independently over things where the ACT can't. Why would the ACT have more body roll than the IRS, it should have less as the solid axle acts as an anti-roll bar. Doesn't matter, go with the IRS , real race cars and off road vehicles don't have solid axles.

 

No joke. Totally good info above me here on all accounts. Though the ACT will articulate a lot (a lot more than a Grizzly 660 will with its anti-sway bar still on), its not going to articulate more than Arctic Cat's IRS models, and its also going to have less body roll than their IRS models as well. So good and bad. But not to any extreme to make either a poor choice. Power to the ground is a weak argument too, because even if there is a difference in the two, its not enough that would make a big enough difference to matter.

The ACT models are quite good (though I prefer the IRS). They are far and away superior to anybody elses standard swingarm rear end, and unlike the old 97-00 models, they have the drain bolt to the rear end tucked away so they don't smack rocks.

 

If you guys have ever ridden behind an ACT equipped bike, you'd understand. The ONLY thing you're giving away to an IRS equipped bike is a bit of GC. Ride is just as good. I don't know where you got the idea that it spins the tires more, it doesn't. It is, without a doubt, the best "straight axle" rear end on the market. The ACT is a four link design, it has probably 2X the wheel articulation of any other bike out there and keeps the tires on the ground as good as any IRS bike. As far as hitting the rear end, I very rarely do. You won't be disappointed in the ACT, try it first, you'll save yourself a bit of money and have as good a ride.

 

I have an 01 ACT but ride with 3 folks on AC FIS machines. I will say I have never spent a considerable amount of time on the FIS machines. Here are MY seat of the pants views and thoughts:

For where we ride I have never had a problem with GC. They do have more, and I will say we have crossed things where I have slid on the belly of my quad.

I have never felt what I would call "body roll". Believe me, I have pushed the thing through some corners nailed!

I have never seen one of the FIS machines body roll.

Riding on another quad and viewing mine from the rear I can see where the ACT shines. It keeps a lot of the bumps out of your tail.

Riding bedind the FIS macines I can see where they shine as well as I watch the suspension articulate and the rider sit nice and comfy.

You almost have to really watch both a ACT or a FIS to see what they are doing for you.

All that said, I decided on a couple of occasions to pass up good deals on newer FIS quads. It all came back to one thing I like about the ACT quads the FIS machines don't have, a tad narrower track width. Very often I seem to find myself in situations where I am navigating between trees or something or other and I catch myself thinking that my FIS buddies will have problems becasue of their width. I will admit that there is not much foundation to my argument as, when it is all said and done, they are still right behind me.

Brent

 

I hear people with IRS complain about broken axle's. How does the ACT straight axle rearend hold up? I've never herd of anyone with a problem.

 

Having never seen horsepower figures for either engine and just looking at the difference in carbs, I would guess, and that is an educated guess, that the AC would have more power with the larger carb. The two engines have different carbs and exhausts systems, so probably not the same horsepower.

 

The ACT system would be more apt to kick a tire loose as with the solid axle it would be easier to get the inside tire, in a turn off the ground making the other tire have to hold all the power. The IRS tends to keep both tires planted as the wheels and tires are independent and they will follow the ground contour seperately and body roll does not cause the inside tire on a turn to lift.

 

A bit of ground clearance? That's like saying an Implala has a bit less ground clearance than a Jeep. It's a world of difference. No arguement that the ACT system is better than the swing arm systems, but for ground clearance the IRS is king by so much that there is no straight axle comparision possible.

 

You haven't heard about any 2005 400's breaking axles and you won't except from the craziers out there. The 2005's have the same axles as the 650's and if you break an axle with the 400 engine it will be spelled "abuse".

 

I just talked to a dealer here in Montana about getting an AC 400. Im still torn between the ACT and the FIS. Mainly because I hear that the ACT handles better with a heavey load (Quartered elk), and it is 45" wide compared to 47.5". I also hear that it doesnt have as much body role. And you can get it in a manual trans. which I think Id rather have.

But the ACT doesnt come with Front Diff lock where the FIS does. The shocks on the FIS are adjustable, and an automatic trans. would probably be better for resale. And is 2.5 inches differences in width really that big of a deal?

Im also hearing that the tire options are better with the FIS (as far as tire size goes) because of the way the shocks angle.

Man o' man, what to do - what to do.