Help me understand wheel tuning for tracks

[AkBillyBow]

First off, I am new to Argos so forgive my ignorance. My brain cannot understand the theory behind placing the smaller diameter wheels in the 4 corners, and placing the taller ones in the middle....and then adding more air pressure to the middle tires. Doing this, you are ensuring that there is no way the diameter will be close to the same.

I would think the most important factor would be having the same diameter on all wheels. Thinking on that line, my brain says to inflate them to 5 psi, measure, then increase air pressure until they all measure the same as the largest one. Then mount them so that the ones with the highest pressure are in the middle....which would actually be the smallest ones at the 5 psi measurement. So that would be totally backwards to what the manual says, and what most people say they are doing....but the diameter of all the wheels would be the same.

Can someone clear this up for me? Wouldn't the wheels being the same diameter be what we should be shooting for to control chain wind-up, wear and tear on the axles, bearing and sprockets?

Please help....my brain hurts from trying to figure this out!!

AkBillyBow

[ARGOJIM]

Plain and simple, clearance. The front and rear axles of the Frontier and Avenger 8x8's are raised for ease in turning.
If you wish to picture it just remove all the tires and run a straight line from front to rear axle.

[Fox Valley Argo Sales]

Tires are a lot closer to to same size from the factory now,but before they could vary in size by as much as 4- 6" in circumfrence.By measuring the tires,and putting the largest in the middle,for example,on a 6x6,the front and rear are now elevated slightly so you are pivoting on the highest point(the two center tires)
However, yes you are correct,different sized tires will create chain wind-up with some types of tracks(rubber),the more the tires differ, the more chain windup could happen. Track tuners are designed for this to "free wheel" the center tires,thus elliminating windup. Todays tires seem to be within an inch or so,helping with this problem.

[Buzz]

Indexing allows some of the tires to slightly overdrive the track so that on axles that have chain tensioners, the correct side of the chain (opposite the tensioner) is under load (sometimes significant load) when operating in the forward direction. This is most of what we do and it's important that tensioners-life is considered. Without a functioning tensioner on longer chains you're in a pickle.

In reverse, fixed-position tensioners see significant load. The tensioner side of the chain attempts to push the tensioner down, and notched design of the tensioner on the frame (preventing downward movement) takes all of the load. We accept this because reverse is only used sporadically. This may or may not be true for some people. I know I avoid using reverse if possible and really try not to put heavy driving or pulling loads on my machines in reverse if possible. A moveable tensioner would more easily handle load on both sides of the chain. I like the older moveable conquest tensioners although some people complain of chain slap (what's the big deal?).

When you don't index your tires, you see a situation similar to what happens in reverse: the fixed-position tensioner side of some chains will get severly loaded (but now in the forward direction). It happens because the track will slightly overdrive some of the tires (because the track speed is set instead by an incorrectly placed larger tire in the front), forcing some tires to rotate faster than the chains inside are attempting to drive them. This belt-pulley effect of the track forcing some tires to rotate prematurely is what causes additional stress on the wrong side of the chain and therefore the chain tensioners even when you travel forward. The weight of the machine alone sitting on center tires means that they will be forced to turn if the track travels too fast, even though they have a small contact patch. The belt/pulley effect still takes place, and the tensioners are pushed down by the chains.

Unfortunately it is rare that all tires hold air perfectly, and you can't always make up the necessary difference with air alone. 5 or 6 psi is a really good pressure for our tires. The tires hold their shape fairly well and do a better job in the track. Beyond that is a little too rough in my opinion, and below that allows the tires to bulge a bit too much in some scenarios.
Indexing is best but still requires your machine to waste some horsepower to "overdrive" some tires (to varying degrees). This load is easily handled by your chain, axles and sprockets. They are bigger and stronger than your tensioners, which are not really designed to last long if improperly loaded.
A track tuner frees horsepower even on properly indexed tires because it eliminates the slipping requirement of center tires that would be necessary to otherwise protect chain tensioners, and track tuners also prevent undue tensioner wear (by eliminating the belt/pulley effect of improperly indexed tires)...which is sometimes done on purpose to swap large/small pairs of tires from corner axles to center axles..to adjust track tension.
Again, track tuners are good, and eliminate the need to fully index your tires. Flexibility is nice to have.
To some extent, having the smallest tires at the corners does help with tub clearance as well, but this doesn't seem to be an issue so long as you don't run crazy high air pressure or suffer tub sag from a heavy hard top. Apologies for long answer.

[philipatmaxfour]

-------wheel tuning for tracks

Indexing allows some of the tires to slightly overdrive the track so that on axles that have chain tensioners, the correct side of the chain (opposite the tensioner) is under load (sometimes significant load) when operating in the forward direction. This is most of what we do and it's important that tensioners-life is considered. Without a functioning tensioner on longer chains you're in a pickle.

In reverse, fixed-position tensioners see significant load. The tensioner side of the chain attempts to push the tensioner down, and notched design of the tensioner on the frame (preventing downward movement) takes all of the load. We accept this because reverse is only used sporadically. This may or may not be true for some people. I know I avoid using reverse if possible and really try not to put heavy driving or pulling loads on my machines in reverse if possible. A moveable tensioner would more easily handle load on both sides of the chain. I like the older moveable conquest tensioners although some people complain of chain slap (what's the big deal?).

When you don't index your tires, you see a situation similar to what happens in reverse: the fixed-position tensioner side of some chains will get severly loaded (but now in the forward direction). It happens because the track will slightly overdrive some of the tires (because the track speed is set instead by an incorrectly placed larger tire in the front), forcing some tires to rotate faster than the chains inside are attempting to drive them. This belt-pulley effect of the track forcing some tires to rotate prematurely is what causes additional stress on the wrong side of the chain and therefore the chain tensioners even when you travel forward. The weight of the machine alone sitting on center tires means that they will be forced to turn if the track travels too fast, even though they have a small contact patch. The belt/pulley effect still takes place, and the tensioners are pushed down by the chains.

Unfortunately it is rare that all tires hold air perfectly, and you can't always make up the necessary difference with air alone. 5 or 6 psi is a really good pressure for our tires. The tires hold their shape fairly well and do a better job in the track. Beyond that is a little too rough in my opinion, and below that allows the tires to bulge a bit too much in some scenarios.
Indexing is best but still requires your machine to waste some horsepower to "overdrive" some tires (to varying degrees). This load is easily handled by your chain, axles and sprockets. They are bigger and stronger than your tensioners, which are not really designed to last long if improperly loaded.
A track tuner frees horsepower even on properly indexed tires because it eliminates the slipping requirement of center tires that would be necessary to otherwise protect chain tensioners, and track tuners also prevent undue tensioner wear (by eliminating the belt/pulley effect of improperly indexed tires)...which is sometimes done on purpose to swap large/small pairs of tires from corner axles to center axles..to adjust track tension.
Again, track tuners are good, and eliminate the need to fully index your tires. Flexibility is nice to have.
To some extent, having the smallest tires at the corners does help with tub clearance as well, but this doesn't seem to be an issue so long as you don't run crazy high air pressure or suffer tub sag from a heavy hard top. Apologies for long answer.

Yes Buzz,that;s a long answer,but an excellent and very helpful one. thanks

[AkBillyBow]

Thanks all for the replies!! Let me chew on this info and see if I have any more questions.

Thanks a lot!! This is a great forum!!!

AkBillyBow

[ARGOJIM]

Sorry Buzz, I didn't read your post yet they are always enlightening But sticking by mine, simply put your hand between the front or rear tires and the body and then the center tires.
Next, uncheckecked and over pressured and


Nuff said.

[Buzz]

I agree that clearance problems are definitely a factor as well when incorrectly placing tires and/or overpressurizing them on tubs that are not ideal clearance candidates. Some tubs are unable to run particular batches of tires with particular track styles. Add to this the mistake of over inflating these incorrectly positioned tires and you rub a hole in your tub. We were recently able to help a machine that did this very thing with an HDI and rubber tracks. After indexing tires, properly inflating, and using a lower profile channel grouser, we went from not being able to run the tracks at all with the current set of tires (and rubber tracks), to running a channel grouser with an abundance of tub clearance. I believe the machine had suffered tub sag from an aluminum hard top and cargo carried on top.

[Sparx]

One thing I would like to point out that another amazing member member "RockDoctor" mentioned to me when buying an Argo was to look for the tub support brace. It actually comes factory on the 700HD and HDI models. This really is necessary and needed on machines with heavy cab structures.
Sorry I have to say this, but how do you guys run so long with the tracks rubbing the body? I could hear mine right away and knew I had to make adjustments to the tracks. I had the rubber tracks and needed to remove the metal center link on the hinges in less then 30kms or 19 miles because they stretched that fast. I don't know how anyone can ride an Argo with that much tire pressure? I'm always 5psi or less, ideally 3-4psi.