When it comes to a machine’s steering suddenly behaving differently than we’re used to, the absolute best place to begin your investigation is always by checking your machine’s tire pressure. Believe it or not, even a few pounds difference between your front tires will be enough to make drastic changes in your ATV’s turning radius – and this will be further exaggerated when in 4×4 as each of the wheels is now driving rather than simply being pushed by the rear.
Inflate both to factory if needed and see if this solves your issue. If not, jack the machine up so that its weight is taken off the wheels and assess the tie-rods and wheel bearings for play. Grab the tire and try wiggling the wheel from side to side. If you are experiencing play here it’s likely you have a worn wheel bearing. Continue investigating to ensure that all the bushings are securely fastened/ not loose or worn. The steering column bushing is one to pay attention to as well as the ball joints on the tie end rods.
In an ideal situation, simply tightening loose can connections can sometimes cure wear spots. In some instances replacement is the only way.
Additionally when under your machine, inspect for damage to frame spars, tie rods, A-arms etc. A bend in any of these will certainly affect the handling of the ATV in motion.
If all of this checks out, give the differential a check. An easy way to check its engagement is to put the quad into gear (all four wheels off the round), engage 4×4 and spin one of the wheels. The wheel opposite should spin at roughly the same speed in the opposite direction. This is also a good time to check your wheels for wobble (out of true) and brake drag. Simply slap the machine into neutral this time and give each wheel a good spin by hand. Wobble will reveal itself and brake sticking will immediately begin to slow that wheel’s rotation.
Diagnosing issues of this nature are all fairly straight forward and intuitive though we would again begin by checking your tire pressure. It is often a case of the easiest fix.