# Arctic Cat 366 Handling Fix



## z24guy

So short story, my dad has an '08 366 with 25x8x12 and 25x10x12 Maxxis 'Zilla's. I replaced every bushing with polyurethane ones due to the stock ones being badly worn. 

The handleing sucked. Above 40km/h the thing was downright scary. It was flipped on its side twice on flat ground travelling at less than 20km/h.

Now the fix? Cut 3/16 of an inch off of the front of the upper control arms and put a shim behind the control arm. This changes the caster angle to be more negative, alllowing the wheels to 'roll over' obstacles instead of impacting into them.

The handeling now? Much better. Dad went from toodling around at a max speed of 30-35km/h to a cruising speed of 45-50km/h with drastically reduced arm pump.

Now I didn't think of this all alone, I have seen it done on a Kingquad and just adapted it to this Arctic Cat. Also I have seen somwhere a set of bushings you can buy for the larger Arctic Cats, but to my knowledge they do not fit the 366.

Now unfortunately I didn't take pictures because I did the work at like 11pm the night before a ride, so I was in a bit of a rush. Hope it helps somebody.


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## greenkitty7

caster mod is great for all arctic cats!


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## Kencat

Hi all, new guy here.

I know this is an old thread, but it won't hurt to continue (I think) as the info is useful.

The modification to put less positive caster on the bike would, to all my understanding, make the bike more UNstable at speed. A good reference is http://www.lsracing.com/img/Guide_21.pdf

If less positive caster helps stabilize the AC 366, then there must be other over-riding factors at work here.

I am interested because I'm not happy with the twitchiness of a "new-to-me" 2004 500 TRV at speed, although I haven't checked toe-in yet which is the first thing to try.

I think the concept behind the modification explained in this post needs to be better explained, because someone might get into trouble trying it out.

Edit:This link explains what is needed to be done to put more positive castor on an ATV, and it explains why. The modification details pertain to a King Quad. How to actually do it on a Cat would have to be figured out.
http://www.nyrocatv.com/techtip.cgi?viewtopic=17


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## z24guy

There is actually a set of bushing you can buy for the larger arctic cats to accomplish exactly what I did for dads 366. And after 1000 kilometers of riding the snot out of it we have had zero issues with this mod. It handles better. It has reduced handlebar feedback. And the changes I made have increased rider confidence because it is no longer like trying to ride a scared rabbit.


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## Kencat

z24guy, thanks for responding. Can you clear something up for me, as the more I read the more confusing this gets. As I read into your first post, you reduced the + camber by moving the upper A-arm FORWARD on the 366? In the Suzuki mod article I linked, they are increasing the caster by moving the upper A-arm REARWARD. On other forums I'm reading that they are also reducing caster on Acs, to make them steer easier. It makes sense that reducing caster will make them steer easier, but that willl also make them twitchier at higher speeds. So it depends on what problem you are trying to solve, I can understand that. But in your case, you were trying to make the 366 more stable at speed, so you should have moved the upper A-arm rearward, for more positive caster. Just trying to get this nailed down right in the ole noggin.


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## z24guy

I moved the upper A-arm forward and moved the caster angle towards the negative.

The problem with it an with most arctic cats from what I've read is that they come from the factory with too much positive caster, which results in hard steering excessive road shock and wheel shimmy.

Now too much negative caster can lead to instability at high speeds, but in reality I likely moved the caster closer to zero, or just negative of zero.


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## Kencat

OK. but you were saying the initial problem was the ATV was "unstable"; flipping over at moderate speeds even. My solution would have been to add more caster for that. Oh well, it worked for you, so that's all good. Another really good reference Re handling, if you haven't read it yet is Improved Handling By: Wyo_H1_Cat at http://arcticchat.wikispaces.com/How+To's It could be that in my case, being that the TRV is designed for two-up, riding single may have the *** end up and the caster running more negative than with a passenger. It actually steers quite easy, even with a passenger. I'll do toe-in first, then play with the spring preload and tire pressures as outlined by Wyo, and go from there.


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