This page is from text captured from others on forums, etc. The author has not have time to verify the accuracy of the instructions, therefore, read over carefully before proceeding. Also the pictures could not be sorted out at this time, therefore they are just "thrown" at the end of this article at this time.
The secondary should come off to make it easier to get to the three nuts holding the speedo drive/ bearing holder. No need to mess with the jackshaft the one on top the lower is the driveshaft thats the one that needs to come out. Chaincase needs to be opened and gears taken off. It will look about the same as the speedo side with 3 nuts bearing holder watch for o-ring around the bearing. Push the driveshaft towards the case side pull the bearing off it slides off then tilt it down with the track and pull it out. The speedo side bearing is locked on with a collar. No need to take it off unless you want to change the bearing. Its a good idea to change the speedo bearing as it is the first one to go since you have it apart already. Get an after market one Cats around $30 aftermarket $10 just as good.
This is a track swap for an 03 firecat F5, but will work with most sleds. Start by loosening your track. use the big wrench in your tool kit to loosen the large nut on the rear shaft, then loosen from the ends of the rails so that the rear wheels loosen their tension on the track. Then remove the 9/16" front and rear bolts that hold your rear suspension in. Do the rear first unscrewing both a little at a time making sure they come out close to the same time or you will have a hard time doing it one at a time as the shaft will spin freely not allowing you to unscrew the bolt. The front arms have nuts on the back side that you have to hold while unscrewing the bolts.
Front hole, located in foot well. Rear hole, located in tunnel support bracket. Now you can pull your suspension out carefully. Now that you have the rear suspension out we can work under the hood. Start by removing your hood, pipe, can, and clutches. (dont have to do primary, but it gives you more room... Now, on the can side, begin by draining the chaincase. Pictured in the diagram, #11 is a drain plug located inside your tunnel just below the driveshaft. Undo this bolt and drain the fluid, or you can drain it by removing your chaincase cover. there should be 6 1/2" bolts holding it on. Put a rag under it to catch the oil. Unscrew the 9/16" chain tensioner bolt approx 1/2" so the chain is nice and loose. Lock your brake on and unscrew the 3/4" nuts that hold the 2 gears on. Note the bottom gear and that the flat side is out, the other side has a "nub" on it... as pictured in 2nd pic. Pull the gears and chain off. Now you can take the bearing cup and o-ring off by unscrewing the 3 1/2" nuts that hold it on. Now, on the clutch side, remove the 3 1/2" nuts that hold the speed sensor on and carefully tap the bolts out and pull the speed sensor off to the side. Grab the driveshaft from underneath the sled and wiggle it so that the shaft comes out of the clutch side and into the chaincase, you can angle it and gently tap the bearing off the end of the chaincase side of the shaft and take the driveshaft out at an angle. You can now take your track off. When putting a track on, make note of the arrows on the track as to which direction it was designed to spin and set it under the sled with them facing in the correct direction.
To reinstall, start by putting the driveshaft back in, bearing on the chaincase side and then o-ring, then cup. bolt the cup on and go to the clutch side, hold the bearing cup in place and place the speed sensor on the bolts (can be a tough squeeze if you have short arms) tighten the bolts on the speed sensor. Put the chain and gears on as one piece noting the direction of the "nub" when reinstalling. Tighten the 3/4" nuts on the gears. Finger tighten the chain tensioner and tighten the jamb nut so it can't back out. Put chaincase cover on and fill to the full line on the dipstick. Put pipe, can, clutches, and hood back on. Put rear suspension back in, starting with the front bolts, then the rear bolts (much easier if you get the tension off the rear springs). Tighten the track, and you are on your way.