I've recently inherited a 2004 Trail Boss 330. On my last ride the I noticed a grinding noise from the rear axle that would get louder when going uphill or soft sand. I am thinking that it's a bearing problem. I'm new to ATV's and have never worked on one before. I'm wondering how difficult pulling apart the rear end would be to replace the bearings.

I also think I need to replace the chain. I've adjusted the tension and it still seems that the chain is a bit lose. I would think that this would be the perfect opportunity to handle the chain as well.

Any suggestion on a good repair manual that may step me through the process or is this a fairly involved repair that I should consider taking to a mechanic?

 

Just jack up the rear end and pull the wheel from side to side to feel any bearing play. You have toremove the rear caliper,rotor,along with axle retaining ring on the left side. Look at the breakdown on your model under "rear housing" Browse Hope this helps,plus not a bad idea to check the sprockets and chain for wear. OPT

 

I also noticed that the spark plug cap is brittle and cracked. My local Polaris shop sold me an NGK replacement cap but I'm not sure how exactly to install it. Should I cut off the old cap, or is it more involved and requires cutting the cable to attach it to the new cap?

 

The stock rubber cap cable was crimped on, just cut the wire at the base of of the old plug cap and screw in the NGK plug cap. OPT

 

Ended up with no time to tackle this on my own so I took it to the dealer for a look. Rear bearings turned out to be fine. Needed a new chain, new bushings for the swing arm and replaces sproket (had broken teeth). It now runs/drives almost like it's new!

 

Thanks for posting what was wrong! A lot of people never post the cause of their problems which could help others with similar complaints. OPT