So is ACT the ultimate compromise between IRS and a regular swing axle? Does it eliminate the body roll on corners and sidehills? How is the ride compared to IRS or a standard swing axle?

 

I have an '02 400 Act. I've test ridden the IRS models before they came out and I honestly cannot tell the difference in ride between the two. There is a difference in ground clearance, of course, and with square tires on back there would be a difference in contact with the ground (perhaps this is why the tires are rounded), but the ride feels the same.

If you go to my photo site and look in the "400 ACT" album (under the "ATV" links) you will see pictures of how my 400 articulates on railroad ties. Someone else here has photos of his 500 (same chassis) doing the same thing.

I can't answer your cornering question because, frankly, I almost never drive at any speed in corners. I'm usually driving slow on some technical trail. I suspect, however, that the Cat's weight and high stance work against it in this department.

I'm sure someone else will pipe in on that one.

 

What little bit I rode the 500i I couldn't tell any difference either. I actuall think that the ACT may have more body roll than the i, don't ask me how. Both ride way better than any swing arm suspension, and keeps the tires on the ground better.
I chose the ACT because, I have replaced more than my share of cv boots. Between my AC 500 ACT & my sons AC 250 4x4 I have 12 to keep up with now. Yes I do run guardes on his but not mine, I've still replaced 3 on the rear of his. I really like the simplicity of the ACT and still get real good articulation (see my pictures). Besides when I got mine they didn't have the i model out yet. After seeing the ground clearance and how it is made. If I had it to all do over again I would probably get the i (but don't tell anyone). I've been riding a AC 500 ACT since 98, I rode all the new models and still ended up with another AC 500. Good luck with whatever you end up with.

 

The ACT suspension articulates better than the IRS. This means that it allows the suspension to flex more. The upside to this is that it will keep all four wheels on the ground longer than the IRS. The downside to this is that the softer suspension has more body roll. In essence the ACT is better at slow speeds where articulation is needed. The IRS is better at high speed because of the reduced body roll.
The IRS has more ground clearence until you start to load it up. As you put weight on the IRS the springs compress and you loose ground clearence. The ACT has less ground clearence but when you put weight on the machine you don't loose ground clearence.
Which is better?... that depends on what you are doing. If you are going to spend your time crawling over boulders with a lot of weight then you are better off with the ACT. If you are going to spend your time riding up and down a trail then you are better off with the IRS. Now, with that being said it is not that the IRS can't climb rocks, or the ACT can't zoom down a trail. It's just that each is just better in their own area.
The thing to do is just ride them both and see which you like the best.

 

I guess it pays to ask questions. The ACT having more body roll is the exact opposite of how I thought it would be, makes sense though.

Pechmial and ttaylor:
Do you guys like your 400s or do you wish you would have coughed up the extra bucks for the 500?

 

Well, Chainman, you have to keep in mind I bought my 400 to play with. I don't own a farm to work or have a large driveway to plow or have any other need for huge muscle, so the 400 is allready overkill for hauling my fat tush around. That said, I am very pleased with it's power and abilities. It's a very solid bike, and I'd have a hard time imagining how I could break something on it. Maintenance is a breeze too. To be honest, if I DID own a farm, or have a large driveway to plow, I still think the 400 would be up to anything I threw at it.

So, no, I've no regrets over choosing the 400 over the 500. My brother wishes he got the 500 instead of the 375, but that's not because the 375 isn't an excellent bike (it is), but rather because my brother just likes the higher number (even though the 375's motor is larger than the one in my 400, he can't quite get over that sticker on the front of mine).[img]i/expressions/face-icon-small-smile.gif[/img]

 

I agree with pechmial, My 400 is plenty strong to get me anywhere I want to go. I prefer the lighter steering it has over the 500. The only reason I wanted to go to the 500 was for the automatic transmission. I just prefer the automatics over the standard transmission. Now that they have the 375 I am looking at buying one for my wife. But, that won't be until next year.

 

HEY Dudes, Well I guess Ill get hammered for this , But here goes , I have owned both a act 400 4x4 and a irs 400 4x4 , never base your opinion on how a machine perforumes on a contorled course , It anit fair , you need to ride it under conditions you ride under , not around a state fair grounds or a parking lot , I had 800 miles on the act , IT did a good job , It did not flex like the irs dose , in ruff ground it dose not ride as good , The body role is not controlable on a act model because of non adjable shocks ,it is on a irs , it is unfair to say that a irs squads more then act , Have you loaded one, be truthful I have , and with the shocks in the lowest notch it out hauled the act with 4 notches to go , I have been more impressed each time we ride with the machine , every thing you go at it dose better , it was tight frist 100 miles , I thought it was not going to have the power the 01 had , but its looseing up now and getting up to stuff ,,Sorry guys I cannot agree with you statments the act is a good machine , But time marches on , I dont feel AC will have act much longer and that IS sad , but that is progress to , to stay on top you must stay ahead of the game , AC having a hard time now , with out big bore engines ever body wants , diff locks , power steering must be next where it ends i dont know , but you must improve to win ! thats what wins ballgames if you stay where your at and dont emprove you lose , SORRY CHUNKY

 

Eric, I don't think anyone will argue with you about IRS having more articulation than the ACT. By it's very design, it should have more. Also, IRS keeps the tires squarely planted while the ACT allows them to tilt. I cannot speak towards body squat, but with the adjustable shocks, I am sure that is controllable.

Chainman asks in his original question, however, if ACT is the ultimate compromise between IRS and the solid swing axel and the answer to that question is a resounding YES.

MOST ATV's sold today use a swing axel rear suspension. These have NO articulation between the two rear tires. That's NONE as in ZILCH. The Act suspension performs NEARLY as well as the IRS while still using the solid rear axel. Arctic Cat is actually AHEAD of the other manufacturers in that they offer some sort of articulating rear end on EVERY ATV they make, not just IRS on their "Premier" models. (Note: I don't count the 90, AC doesn't even make that themselves).

Until the "competition" starts offering IRS on every model they sell, the ACT suspension will still be around. It is remarkably better than the swing arm suspension (and in some cases the IRS) of it's competators. When I test rode these at the "State fair" conditions you speak of, Eric, (and no, I didn't take any offense, don't worry), it was over a "Belgium road" of alternating logs. I could do 10-15 mph over these on the AC Act and IRS models, but anything over 5mph on the competative machines and I would have been thrown off.

If the IRS would have been available when I bought my 400, I would have bought it. But I don't miss it, either.

 

Pechmial,
I also thought that the IRS should have more articulation than the ACT. Last evening I put my right rear tire (2002 400i 4x4) on a 10 inch block, and all tires were contacting OK. Then I drove the quad on blocks so that the right rear and left front were on the 10 inch blocks. I felt quite comfortabel doing so, but when I got off I was amazed to see the other front tire completely off the ground! I even jumped up on the rack to try and compress the suspension but NO GO.

I was quite surprised by this. My quad only has 55 miles on it, and I am hoping that it will loosen up a bit. If it does not, then I probably bought the wrong quad. I do a lot of hunting, crawing through bush etc and over beaver dams with lots of fallen trees at odd angles. I thought the IRS would be a champ at this. I do remember sitting on an ACT model on the dealers floor and commenting on the body roll I could induce by shifting my weight. My IRS model does not do that.

I guess only time will tell. I am sure this quad will do all I want it to but maybe to get the high clearance I sacrificed a bit of articulation?