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ATV front end alignment question

352 views 6 replies 3 participants last post by  junkyardwarrior  
#1 ·
My old beaten and bruised Polaris Sportsman has been eating up front tires with one side worse than the other. I've adjusted the linkage and tried to get it as square as possible and it's better. I used to really have to fight it if it was on pavement. Not quite that bad anymore. I've checked the front end and made any and All repairs but still can't seem to get the front tires lined up. What is the correct procedure to get it set right? We have two and I noticed the newer one has a slight toed in look and it still has the original tires with even wear. I jacked it up again today and couldn't find any slack or looseness.
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#3 ·
unless you have adjustable control arms the only adjustment you have available is toe, which you adjust with the tie rods.

But you'll also need to make sure there are no worn bushings, wheel bearings, ball joints, struts, etc. That will affect a lot of things and you can't "adjust" mechanically worn parts enough to be safe/comfortable to operate.

to adjust toe, you need to roll the ATV forward about 10 foot or so on flat ground (shop floor works) and stop, lock the brakes or keep it from rolling backwards. Make sure the wheels are pointing straight ahead. I just drive it across the floor and line it up with one of the expansion joints. Adjust toe so that front is about 1/4" shorter than the rear. You can go to zero if you want but it makes little difference as it changes with suspension movement anyway.

a lot of people will eyeball them and it is rarely close. Some guys can get real close, but I don't trust my eyes. I can make it "look" perfect. Get the tape measure out and it's 2" off. While on that, measuring can be a bear because the lugs on some tires are asymetric. "Most" are symetrical enough to make it work, and most have a center mold line. Hook the tape measure on the same lug front and rear, and use the mold line to take the measurement.

pavement kills tires, period. Hard pack does as well (dirt roads). Try to avoid those if possible.

also make sure your 4x4 is fully disengaging on both sides. And brakes. I've seen a few older sportsmans lately that the old brake fluid has congealed and is causing the caliper(s) to stick. Fluid won't back up in the master cylinder so as you ride, and the front rotor(s), the pads, etc all heat up and expand, they'll apply pressure-causing drag. Sometimes it's unnoticed. I'd highly suggest flushing the brake fluid if it hasn't been done. If they're sticking like that, hopefully the flushing will solve it. If not, may have to put a master cylinder on it, if it's still available. Some of the older ones are NLA.

The newer ones use a slightly different design/different suspension geometry, and possibly a totally different design for the AWD system depending on which one you have.

road crown on paved and hard pack surfaces doesn't help any, which is usually why one side wears more than the other.
 
#4 ·
^^^this is almost exactly what I would have said. If everything mechanically checks out you need 1/8-1/4 toe in to drive best, in my experience.

How I got my old truck in good enough shape to drive was get it lined up as good as possible like junkyard said. Then, I took two Jack stands and placed them about three feet in front and rear. Stretched a string between the two and set the rear one so the string was about 3” from the rear wheel and at a height about the center of the wheel. Moved the front jackstand until the string was square (same distance) from the front and rear edges on the rear wheel. That should put the string close to square with the machine. Now you can measure the front and rear edges of the front wheel and adjust until the front is 1/16-1/8” further from the string than the rear edge. Once done, move to the other side and repeat. Measure the wheel, not the tire.
Hope that description makes sense. Takes a bit of patience to set up.
 
#5 ·
I'll have to read that a couple of more times before I dive into trying. Appreciate y'all's help. I'll double check the ball joints and bearings before I make another attempt. Thanks again guys.
 
#6 ·
I drew something out that explains a lot easier. With the string measurements the same on front and rear edges of the rear wheel means the string is square with the rear wheel/axle (if the wheel isn't bent!). The measurement on the rear edge of the front wheel will most likely be different that that of the rear wheel. The fronts may sit slightly wider than the rears. What you are wanting is a measurement on the front wheel where the front edge is about 1/8" more than the rear indicating it is pointing inward just slightly.
 

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#7 ·
sometimes string method is had to use because the track width difference from front to rear is different, like on my car the front track width is about 2" wider than the rear. Plus cars need a much tighter tolerance. But on ATV, it can be an inch toed in or out and it's not a huge difference. Kawasaki Mules, some of them had spec of 1-2 inches of toe-in. Crazy, but that's what they designed into them.