Hi, yep i bet its that constant clonk clonk or click click noise, your cvs are well worn, like mine, but with lots of grease (red lithium) put in the top of the hubs with some tlc off roading they will still last for years - mine have touch wood. This is what i love about free wheeling hubs, when in free mode all that turns is a couple of wheel bearings, saving the front prop, diffs, shafts and cv's from turning and increases fuel economy big time. When the hubs are locked a spring pushes up a spline onto the drive shaft output in the wheeling hub area and makes a connection - dead simple. Turn the wheels on full lock, take of a wheel at a time and in the top of the hub behind the brake disc is a nut head, 24mm size socket - good fit undo it and put in lots of grease, the noise will go away unless severly bad cv's. All the cv is, is a shaft connected to the diff comes along the axle chube, has a nobbly cup with groves cut out, in these grooves big ball bearings sit, then in turn its almost simultaneous out the other side but with a bigger cup to hold all the balls in, the balls wear but last a hell of a long time, they do get dry with heat etc if not serviced properly, but its these balls which are grinding making that clonk or click noise when wheels turn in 4wd etc, i love old fourtraks to work on, the hubs and axle parts are a doddle its all nuts and bolts, dead simple to strip em, you could buy new ones (milner off road)but expensive - only do it when they go bang but im against buying secondhand ones of these cos its not worth it - probably get same problem very quickly unless you know about what your buying,hope this helps