Ok folks, my speedometer recently died on me and in doing research on these forums I figured my drive shaft bearing (PTO side) was probably due for replacement. However once I got in there I found the MAG side bearing was worse than the PTO side. So my sled got both new drive shaft bearings and a jackshaft bearing while I was in there. About $50 in parts and 12 hours later I am done. I am attempting a walk through here for anyone who may have this problem.
This was done on my 93 Ski Doo Formula MX but I think the basics are the same for most sleds. Also keep in mind, I actually did this with the sled sitting on my trailer since I was too lazy to unload it.
1. Jack up the back of the sled so the track is off the ground.
2. Loosen the track. Sorry no pics but this is easy to do. You should have a clymer manual if you don't already.
3. Remove the driven pulley. This will allow access to the PTO side bearing where the speedometer cable goes. Remove those 3 nuts you see in the picture and the speedometer cable.
4. Next you will need to remove the chaincase or chaincase cover from the MAG side. To do this I had to remove my airbox, exhaust, and my overflow container to get at the back bolts of the chaincase. Although not in the picture I removed the entire chaincase to clean it up and replace both bearings in it. The pic you are looking at is after I put it back on with the new bearings in it. I bought sealed bearings but I removed the seals on the inside of the chaincase since this is the way it comes from the factory. The back side seals were left on.
5. With the chaincase now remove and your track loosened, the drive shaft can be moved back and forth. There is no need to take it off the sled.
First push the drive shaft to the PTO side and use a bearing puller to pull the bearing off, then you can put the new bearing on.
Now replace the plastic piece that goes in the PTO end of the drive shaft. This is the piece that the speedo cable hooks to and costs about $2.
If you opt to leave your chaincase on just push the drive shaft back to the MAG side and reassemble everything. If you pulled your entire chaincase off like I did to replace all the bearings put your new bearings in with the chaincase off then reassemble.
I didn't think this job was that hard, I just took my time. I spent probably 12 hours over a few days. I also had a clymer manual which helps since it has diagrams on how to put your gears back in the chaincase.
6. Adjust your track tension and make sure it is aligned. I would also adjust the clutches while you are at it. Don't forget to refill your chaincase with oil.
7. Hit the trails and enjoy!
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