a buddy of my dads has a polaris explorer 500 the problem is whenever U go along the back riight wheel starts hopping and slows down it is very violent and it becomes unrideable. to me I think the universal joints are binding what do U guys think. rember ride SMART and ride hard!!!!!!!!

 

Sounds like bad rear axle bearings.

 

I had a rear u-joint go out on my sp500 and all it did was get noisy. Can't you pick up the back end and give it a spin. If the u-joints are bad I would think you would see them jump a little.
Just a thought,
Sparke

 

If im thinking right.. the Explorer 500 is the chain drive 500 utility bike right?..
If so, I'd say its either a bent axle, bent wheel, bad axle bearing or a tire full of water..
You can try swapping out the rear wheels with another machine, or swap the wheels (left to right) and see if the violent shake goes to the other side...
Another thing might be to jack it up and take the rear wheels off of it... BLOCK THE FRONT END.. and run it in 2wd and just WATCH the rear axle.. see if its bent, then shut it off and grab the axle at one end.. try to rock it up, down, left, right, in, out... to check the bearings...

 

Sounds like it is full of fix a flat stuff and it has settled to the bottom or the cords in the tire have seperated and there is a bulge on the tire. I had a Titan tire go bad and cause a problem. Sounds like a tire balance problem.

Dan