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Discussion Starter · #1 · (Edited)
Cut and Paste of some text I found on the Internet. http://forums.atvconnection.com/arctic-cat/269306-how-do-you-make-ac-handle-better.html This is not my original idea. The idea works though

First of all lets start with tires. All tires 'roll-under' some roll more than others. 2 ply will roll more than 4 ply and 4 ply more than 6 ply etc. Why? because 6 ply have stiffer side walls than either 2 or 4 ply. The stiffer the sidewall the less roll-under. What does roll-under do - it causes oversteer (makes you feel like it is doing a nose dive over the outside wheel while turning) or (the sensation that the front is tucking under). If taken to extreme the machine will roll onto its side. In a nut shell 'roll-unders' can cause 'roll-overs' How do you stiffen sidewalls? Simply, add more air or add tubes or both. With that said.
On to profiles (sidewall height) - a low profile tire will always have less 'roll-under' than a tall profile tire. A 25 inch tire has a lower profile than a 26 inch tire and a 26 has a lower profile than a 27 inch etc. So in a nut shell again a 25 inch tire will always give you superior handling characteristics over a 26 inch and taller tires. A side note here, a 25 inch tire will also accelerate faster because it maintains a lower gear ratio. And also if your engine because of the gear ratio change may not be able to pull the full RPM range, you may find that the 25 inch tire will also run a faster top speed. It will certainly get to the limiter quicker and it will also put more power to the ground. (Same principle that you are putting more power to the ground in low-range than in high-range).

Now let's talk about springs and suspension. General rule - soft suspension grips and stiff suspension doesn't. You get most all the stability from the rear suspension. By stiffening the front you are counter productive in making the machine stable and in fact making it more unstable, and if taken to extreme it would make your machine mushy in the rear like you had a flat tire back there and the rear would float and feel squirrely. (This is why sway-bars are attached to the rear and not the front).

So what actually happens when you turn? Well to a degree you need to slow down, this causes weight to be transferred from the rear to the front. And when you actually initiate a turn some of the weight from the inside is transferred to the outside. This puts a heavy load on the outside front wheel. Remember soft grips and stiff doesn't, if your springs are too stiff (which you may think would assist in handling the weight transfer and make the machine more stable - it doesn't) the machine will plow or want to go straight. Remember the rear does the stability not the front. If the front is soft it will absorb the weight transfer and grip, a stiffer rear will keep it from feeling tippy. (we actually do have some extra stiffness in the front by having appropriate air in the front tire to stop 'roll-under' - tires to some degree are like mini springs - but without the control of rebound or compression that a shock offers - all we can do is to remove some those properties by making the tire stiff). This way the shock can do its job in a controlled fashion, with minimal affect from the tires rebounding and compressing uncontrollably. The front and rear do just the opposite as well as the left and right. When we load the front we are unloading the rear and visa versa. When we load the left we are unloading the right and visa versa. What is loading and unloading - simply, transferring weight.

Ok now we go into a turn.
If the rear is too stiff or the front too soft we overload the front causing the rear to be excessively unloaded (light - loose) - results are the rear will prematurely slide and the front will oversteer and we may actually have to counter-steer (steer opposite of the turn) to keep the machine from spinning out or having a tuck and roll if the tires are too soft and 'roll-under'. This is called 'loose going in'.
If the front is too stiff and the rear too soft we have the opposite in that the front will understeer or plow because it is not being loaded enough (too light - too stiff) and if the tires are too soft and 'roll-under' we will get the feeling that we want to do a handstand on the handle bars and the inside rear tire may in fact want to leave the ground because the right rear is loaded to heavily and wants to go straight and the inside rear wants to get to the outside (or jump over the outside rear - because the outside rear is planted too firmly - it is soft and has grip and has not given up its weight). This is called 'tight going in'.

A good turn is to have the front soft, load the weight, grip and head into the turn. The rear needs to be stiff enough to allow weight transfer forward and give up its weight to the front but not so stiff as to go loose but only to follow the front to the apex (the point at which the turn basically is complete and we have negotiated the entrance) of the turn, at this point we are ready to hit the gas to unload the front and to load the rear again. On occasion this may cause the rear to break loose or loose traction and slid a bit. Once that is complete and the transfer of weight is almost done the rear will load to the point of hooking up (it has no enough weight to get traction), the front has unloaded and now rebounding and becoming light, we may even be able to loft the inside front tire off the ground. We are basically about out of the turn completely and headed straight again.

On to track width. A wider track will always offer better handling. Here is the simplistic physics and geometry behind that principle. A wide track offers stability from left and right weight transfers by decreasing the angle of tippiness. Instead of the weight wanting to go to the outside of the tire it is directed to the inside of the tire causing the suspension to squat rather than roll. Thus in effect simulating a lower center of gravity and not transferring as much weight. Thus confining the transfer of weight within the track width and lessening the transfer to the outside. You can get a wider track with offset wheels or the addition of wheel spacers.

The basics in a nut shell.
1)stop the roll-under from the front tires - low profile and stiff sidewalls & more air.
2)soften the front suspension - to counter the stiffer tires and to more easily absorb the loading of weight without throwing it to the outside (tippy - tuck) or resisting to accept the transfer (plowing - too stiff)
3)stiffen the rear suspension - to enhance the unloading of weight and become light enough (give up some traction) to follow the front (without premature loose going in) and to be light enough with less traction to be able to slide if necessary (at the apex) in order to complete the turn and to get heavy again only when the gas is applied and to hook up.

Any comments, suggestions etc are welcomed contributions.

My question back to all who write to me or in person ask me about the handling is: Why would anyone that already has 12 inches of clearance (industry leader - when all others have 7-11, and basically are forced to make their machines handle worse to gain GC) and has a tippy machine (by nature), want to make the machine handle worse by putting taller tires for a meager ½ inch of clearance, that may be of benefit once or twice a year, in a special situation? And the taller the tire the worse the handling.

Originally posted by: AC4LIFE

im not saying b/s or anything on what you've stated buck, but i just want to ask some questions to clear some things up. ive had the settings on soft in the front before, and the ac's have powerful brakes, once i grabbed em a bit, rather than being progressive, and the front squatted and the back end came up, luckily its just stood on its nose and didnt come over the top anymore. what im trying to get at is that b/c of the long travel and tendency to have the front end dip under either braking or cornering, is the reason i have them set to stiff, to limit that movement. id rather have my machine slide a bit in a corner than have my outside front wheel grip and that corner compress and the machine come up and over, which has happend to my father and almost a few times with me. now if any of my assumptions here are wrong, please let me know and correct me, im on these boards to learn about stuff not blab on thinking that i know all. just curious.


You are correct. Different machines may need a little different setting as well as with different riders (remember there is body english too). It is all about weight loading and unloading and your wheight plays into that too.

The major improvement is to stop the 'roll-under' with the front tires. Once that is accomplished then the rest is a matter of personal taste and how a person uses their own body weight with the machine. You seem to prefer that the front push a little - and that is fine. I on the other hand don't like it because when it stops pushing it will grab and there is a sudden snap to the turn.

If you like your front springs a little stiffer that is ok. But you may find that the rear may have to go up also for a good balance... i.e front on 1, rear on 2, then you adjust front to 2, you may have to put the rear on 3. See what I mean.

When you get everything done, a good balance is a machine that will enter a turn too fast and all 4 will slide. Not just the front and not just the rear. As a general rule most setups will have the rear stiffer than the front. What I meant with having soft suspension while setting up handling is that soft will grip and stiff will slide. If you have a machine that is gripping too much in the front then you make it a little more stiff to unload the weight and by the same principle if the rear is sliding too much while entering a turn then you soften it a bit. You can stiffen and soften with both the shock preloads and tire pressure.

All things are not equal. Your front springs from the factory may be a tad softer than mine. My rear springs from the factory may be softer than yours.....

I did the whole article so that people would know what to do if their machine was doing a certain thing. If you go into a turn and the machine wants to go straight or plows then you can either soften the front or stiffen the rear or both and you can accomplish this using both the preloads or tire pressure.

A lot of people thought that if it was tippy then if you stiffened the front that would take care of it - well to some degree it would but then your machine would push like crazy. The tippy is really controled from the rear, that is where you get the stability for the most part.

The article was done so that people when making changes would have some degree of knowing what was going on and not just keep making changes on a trial and error and getting frustrated.

The biggest thing is to stop the roll-under from the front tires. That could mean 6lbs, 8lbs 9lbs or air or putting tubes in the tires or getting a 6 ply tires etc etc. or any combination mentioned. But for good handling the 'roll-under' from the sidewalls of the tires is the first thing that must be adressed and eliminated. Then you can get on with the suspension... once the suspension is set then you may find that you can take a 1lb of air out.

The whole point is that the ill handling and the tippy feeling from the AC's can be addressed and the handling can be greatly improved (and you don't have to do trial and error - that if you know what is going on and what to do then you can make adjustments appropriate to improve the handling). Some people did not know where to start or what to do. Some people didn't know what was happening when it felt like you were doing a handstand on your handle bars or that it felt like you were going to do a nose dive over the outside front wheel. I made an attempt to let them know that when this particular thing was happening, here is why it was happening and here is what you can do to correct it.

So in your case where the front seems to be too soft then yes stiffen it but don't forget about the back too, If you stiffen the front and your handling goes away don't think that you have to set it back, you may only need to add more air to the rear tires or go up one preload setting to bring the handling back.

Here is a fun exercise that you can do to really understand grip and slide.

Take your machine and set the front preloads on the softest and your rear on the stiffest. Put 4 lbs of air in the front and 10 lbs in the rear. Then on asphault at 1 or 2 mph turn left then right. You will see that it turns pretty easy. It may steer hard but it will turn easy - there is a difference between steering and turning.

Then do the opposite. Put 10lbs in the front and the preloads on the stiffest and in the rear put the preloads on the softest with 4lbs of air. Then do the same turns left and right and you will see that the thing just does not want to turn.

Test both settings driving forward as well as backing up.

Slide = giving up traction (to any degree even ever so slight) and being light.
Grip = holding traction and being heavy.

I would start by making sure that my front tires are not rolling under. Start with 5 lbs in all tires then go up 1 lb at a time on just the front tires and see what changes in the handling characteristics. Or you could start with the fronts at 12-14lbs and come down on pressure - this is the way I do it - I only have to add air once then let some out as I go until I feel that it is turning good and the side walls are not rolling under.
Once you have the front end pretty well set then the rest of the work is done with the rear. Either spring stiffness or tire pressures.
A confusing situation is a feeling that when you go into a turn that you seem like you want to do a nose dive over the outside front. You may feel that the front needs to be more stiff, but in fact what is happening is that the front is too stiff and plowing and the front tire is rolling under and when it hooks up (by this time you have loaded way too much weight from the rear to the front - and it dips) it sort of snaps and gives you a feeling like you want to do a handstand on the handle bars or that the machine is going to tuck and roll. The fix is not to increase the front spring rate but to increase the tire pressures and decrease the front springs. This way the front can squat (from a moderate loading of weight) and grip and the side walls on the tire will not tuck under, and the back will just unload enough to follow the front.
The more your machine pushes in a turn the more the rear will keep trying to load the front with more weight until it turns or you slow down enough to cause the back to stop loading the front. This is why a soft front end will load quickly and squat and go into the turn (but you need to have your tire sidewalls stiff enough not to roll under). The rear at this point will stop trying to load the front and will just follow it. If the rear is too stiff it may slide because of the momentum from loading the front and if the front is in the turn the rear just loads it to the outside and thus a slide. Remember, a body in motion tends to stay in motion until an equal or greater apposing force acts on it.
If a moving ball is met with resistance (bat) it reacts violently in the opposite direction (too stiff on the front) but if the ball is met with a soft catchers mitt, it just absorbs the energy and stops (soft front springs).

Here is something fun you can do.
On dirt - like a dirt road or some such. Start driving in a big circle and keep increasing your speed and note what the front is doing. Are the tires really scuffing hard, are they just tracking good. At some speed they will start to scuff and push. Note that speed.
Then add about 25-50 lbs to your front rack and do the same thing. If you can reach a higher speed before the front starts to scuff and push that means your front springs are too stiff or the rear is too soft.
Then put the added weight on the rear rack and do the same thing. If you reach a higher speed before the front starts to scuff and push that means the front springs are too soft or the rear too stiff.
There is no balance this is only done to give you an idea where to concentrate your efforts. Either it be making the front stiffer or softer, and the same holds true for the rear. If the front was gripping too good going into a turn, this means the rear is too stiff. You may want to try setting the rear preload to 2 instead of 3 or you can sit a little further back (body english), Play around with it and you will find a setting that is pretty good for you.

Disregard what I just said I forgot that you said the rear was lifting and the front wanted to tuck - Decrease the front tire pressure and or the front preloads. The front did not take the weight soon enough and the rear kept trying to load more and trying to drive the front into the ground and ended up overloading the front and then attemped to put even more by lifting (this means that the rear had too much traction and did not give up enough weight to the front soon enough to become light and loose). In wet conditions the rear should have simulated or actually been loose going into the turn and slid out very easily - thus you are too stiff in the front.

There is nothing wrong with AC. The suspension and tire pressures just need to be tuned from the factory settings. My experience has been that once tuned the AC can handle better than most and can be right there with the best of them. Actually if you spend some time, the AC IRS and run with an SRA. Plus with AC you get a host of other bennies such as the industry leader in GC and wheel travel. Doesn't get much better than this. AC as well as all ATV's the demon is the 'role-under' from the front tires.

The post was done so that people could tune the suspension and really get the benefits from the AC. Rather than blindly make adjustments, to be able to know what to do in order to get the results that you want. If your machine is behaving in a certain way, some things that you can do to correct it and not just blindly, hit or miss, make changes.

This post has not only helped AC but several other brands, based on the private messages I have received. It all makes my heart smile to know that it has done some good and people have benefited, no matter what they are riding.
 

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This should be pinned Not worthy:
 

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I second that motion... Should be pinned
 

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I thought I had a fair "handle" on suspension and handling for quads. Doh!

This is great info, and there is lots more in the link. You know the feeling when you learn something that applies to everything you are doing, and you can't stop thinking about it? My brain is heating up.

So if we want to get into nitty-gritty specifics and have a giant discussion, should we have at it here in pinned topics, or start a new thread in general or performance?

Mike
 

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Where'd the first post go?

BTI
 

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Hey just wanted to thank you for taking the time and putting this post up.

I installed "Ride in Springs" on my 500m and had them set on the softest settings all the way around and man did it plow under throttle or off, I set my rear spring preload to one knotch less then max and it steers SOOO much better now it does not plow at all and will bring the rear end around if turned to tight lol never did that before.
plus putting the springs stiffer in the rear took out the body roll..

big :thumbsup: to you :)
 

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Discussion Starter · #12 ·
<div class='quotetop'>QUOTE (gwc @ Sep 30 2009, 03:48 PM) <{POST_SNAPBACK}></div>
Hey just wanted to thank you for taking the time and putting this post up.

I installed "Ride in Springs" on my 500m and had them set on the softest settings all the way around and man did it plow under throttle or off, I set my rear spring preload to one knotch less then max and it steers SOOO much better now it does not plow at all and will bring the rear end around if turned to tight lol never did that before.
plus putting the springs stiffer in the rear took out the body roll..

big :thumbsup: to you :)[/b]
Now do the Caster Mod and it will steer even easier, like a whole different machine
 

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Yeah I need to do that as well, but i have a arm bolt thats froze in the top a arm and have not got in the mood to cut it out and all that stuff..lol

But thats on the list of to do's.. :)
 

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GREAT info for my noggin'

now i just need to stiffen up the rear spring and play with my TC ride in's

slap on some sanny bushings and rock n roll.
 

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<div class='quotetop'>QUOTE (six-ohh @ Mar 12 2010, 05:41 AM) <{POST_SNAPBACK}></div>
GREAT info for my noggin'

now i just need to stiffen up the rear spring and play with my TC ride in's

slap on some sanny bushings and rock n roll.[/b]
I thought those new bushings were only for bikes without ride in suspension?
 

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Discussion Starter · #16 · (Edited)
<div class='quotetop'>QUOTE </div>
I thought those new bushings were only for bikes without ride in suspension?[/b]
Ride in suspension has nothing to do with caster mod. Ride in suspension is really just a change they made in shock springs. Ride in suspension first appeared in 2008 on only the 700 H1 and the Thundercat. The spring rate is softer in the first couple inches of spring travel. You can replace ride in springs with non ride in springs and make it identical to a non ride in suspension model.

In 2009 they made changes to the A-arms that changed the caster on all 400 and up machines. This along with a different wheel offset makes the 2009 and newer machines easier to steer. Using the caster mod bushing set with the 2009 A-arms could be too much of a caster change. So to sum it all up.......

Use bushings with the caster mod on any 2008 or older machine with or without the ride in suspension.

Use bushings without the caster mod built in on 2009 and 2010 machines with or without ride in suspension.

I don't think anyone has tried the caster mod on a 2009 or a 2010 machine, they steer well enough as it is. I would not recommend doing it either. Doing the caster mod to an 2008 or older machine makes them steer as easy as the new 2009+ models. I really doubt if you can make a 2009 much easier to steer and may end up making it handle poorly or even dangerous. The same thing can be done by reducing the caster too much on the older machines. There needs to be some caster for proper handling.

UPDATE: I understand the caster mod does work out well for 2009 and newer Cats, No personal experience though, Contact ricktherocket for details on his Steerlite Bushings.
 
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Very informative, thank for taking the time to write it. So I should be looking into just a set of regular a-arm bushings should mine wear out? The bike is pretty new so hopefully I wont have to worry about that for a while.
 

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One thing that I don't see addressed is wheel hop when losing traction.
Is going stiffer on the rear springs going to make it better or worse? I know it was stated stiffer=less traction.....but if it is less hopping, that may be an OK trade off.
I am thinking that it might be time to start tuning. Everything is on the softest setting. The tires are at around 6#.
Right now, my machine is plowing slightly in turns. This is all on ice.
Should I just leave it alone
 

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Discussion Starter · #19 · (Edited)
One thing that I don't see addressed is wheel hop when losing traction.
Is going stiffer on the rear springs going to make it better or worse? I know it was stated stiffer=less traction.....but if it is less hopping, that may be an OK trade off.
I am thinking that it might be time to start tuning. Everything is on the softest setting. The tires are at around 6#.
Right now, my machine is plowing slightly in turns. This is all on ice.
Should I just leave it alone
Good questions and I don't have an answer for you either. I was not the original author of that information. I found it on another website and tried the idea behind it. Worked out well enough for me that I decided to share it. I'm quite happy with the results I'm getting, handles and turns well with very little plowing. Clean the adjusters well, lube up with something like WD-40 and jack the ATV up to remove weight from the springs when making preload adjustments. Much easier.

If you haven't already, throw away that cheap spanner wrench AC provides and get a good one or use large channel lock pliers. The stock wrench is good for only one thing, bloody knuckles.

I've also done the Caster mod for improved steering ease. Everyone may like something different and since may be using different tires there is no ideal setting to recommend. It's something you just have to try out and test for yourself, your weight, riding style, and your tires. I do believe it's safe to say there are improvements to be gained over having front and back set up identical in my opinion. You'll get your worst handling if the front preload is set stiffer then the rear. A BIG MISTAKE
 
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Wow thanks for the great detail you went into for this. It sure helped me out alot.And cleared up alot of questions I had .I was starting to think that maybe I bought the wrong Quad ,but maybe not. I'll go know and start setting mine up properly .Thanks again.
 
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