I've ordered a new 2.1 reduction unit and a 60-in., two bladed prop. I removed the crank shaft cog bolt utilizing a strap wrench. However, I can't get the cog off the shaft.

Any recommendations?

Thanks, Gerry :)
  • Re: Removal of 503 cog gear from crankshaft.

    by » 13 years ago

    Rotax makes a gear puller that screws into the inside of the cog gear which works great. Unfortunately, it is $200.00 US. If you can find someone to lend you one, that is definitely the way to go. I have used the claw type pulley pullers but you have to grind down the ends somewhat so the claws will go behind the cog. There is very little room between the gear and the crankcase for the claw end to fit. Use a coin or some washers inside the cog so you don't ruin the threads in the crankshaft when you tighten the puller. The cog fits very tightly so don't be surprised if it takes a lot of pressure to pop it loose. Try do do it without using heat on the cog. The rubber oil seal can be damaged otherwise as it is right behind the cog. Again, the claw type works, but use the rotax screw in type puller if at all possible.


  • Re: Removal of 503 cog gear from crankshaft.

    by » 13 years ago

    I needed to do this on my 503....I spoke to my local Rotax dealer and he told me only to use the correct tool....or risk damage....cant remember but I'm sure he said the gears come as a matched set and cost $$$$$$$$$$$ so not worth risking is, I bought one £60GBP,

    The torque on the retaining bolt has recently been increased....from memorey I think it was 45nM and now 60nM....but I would need to look it up to be sure.


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