my atv will not move when i put it in any gear, .I took apart the rear differential and noticed the ring gear was a liitle worn i was wondering if anyone new if that was the problem or maybe it was the tranny?

 

Should still pull with front differential .. I would check manual clutch adjustment and if that's ok then I'd remove the clutch cover and check the manual & centrifugal clutch/s ..

 

the front differential doesnt work. but when i put it in gear i can hear it engage then the part that connects to the ujoint turns so does the rear diff but when i had the tires on they did not turn at all. so iam thiking that the ring gear is bad its pretty worn i think its original would that be my problem? or do you think that its still my clucth or maybe both?

 

The 400FW only had 1 seal on the drive shaft coupler on the front drive shaft , water would get in and rust the splines then they would strip ...
On the rear if you start the bike put it in gear , remove the rear differential oil cap , is the ring gear turning but axle not turning .. ? .. If so then the axle is stripped .. But if the drive shaft is turning but the ring gear & axle are not turning then problem is with the pinion ..