hi it quite simple really i have done mine. first you have to take the hub off, you will need allen keys for this, undo the small screws first on the auto hub (shouldnt be too tight) then undo the bigger bolts with an allen key, (i had to get a bar on these as they were really tight!) then there is a bolt to undo on the end of the drive shaft undo this and then the hub should just slid off. if you have manual hubs it the same but there is a cir clip instead of a bolt, and you must make sure they are in the 2x4 position.
next

losen wheel nuts
jack it up
take wheel off
remove the brake caliper (one 14mm bolt)
remove pads
then you need to remove the pad holder, (2 19mm bolts)
on auto hubs there are a few moor bits to remove from round the shaft they a a big cir clip then there are 3 tiny srews to remove these are star type screw (not a philips or a possi), you will know what i mead when you see it. then you need to remove the ring.(this does not apply to manual hubs)
then you can see the big nut which holds the bearing in (about 50 - 60 mm!!) however i used a scredriver and a hammer to knock it round then it will just undo.
remove bearing
then the disc will come off.

undo the 4 nuts holding it to the wheel studs (14mm)

put new disc on
and put back together.

hope this helps don't think i have missed anything off, although i have a fourtrak i would imagine it is similar if not the same on a sports track.

ßen