Sunday, February 19, 2012

Snowmobile Clutch Removal

I had a Polaris 550 snowmobile in the shop that I needed to pull the clutch off.  This first photo shows the back side of the clutch after the job is all done and it is laying on the work bench.  Sometimes I like to make the first photo something that will look good in the little thumbnail size where this blog is advertised over at the Rudstrom Family Blog.

The first step is to get the correct clutch puller and put some anti-seize on the threads.  There will be tremendous pressure on the threads when it is in use and this will help prevent it from binding up.

They are called clutch pullers, but a clutch pusher would be more accurate.  The tool threads into the clutch body and pushes on the end of the crankshaft.  This forces the clutch off of the tapered end of the crankshaft.

The bolt in the center of the clutch is removed and the puller is threaded in.  On this Polaris machine there is a hole placed in the body for this purpose.

The next trick is figuring out a way to keep the engine from turning over while you screw the puller in.  If you have an impact wrench you can simply buzz it in and the inertia of the engine is enough to keep it from turning.  On some electric start machines you can jam something in the teeth of the ring gear and hold the engine that way.

I have found that the best way to hold the engine is with a piece of rope pushed in through the spark plug hole.  Turn the engine so that it is a little way before top dead center, push a small rope into the cylinder until it is full, then turn the engine so that the piston pushes it against the head.

When doing this make sure that you don't start with the piston too far down in the bore or the rope may go out one of the ports.  If using this technique on a four stroke engine make sure that the piston is on a compression stroke so that the valves are closed.

This method works well on small and large engines.  I once used this idea to hold the crankshaft on the engine in my truck when I was trying to change a timing belt on the side of the road.

You normally have to screw the pull in very tight and when the clutch finally lets go it comes of with a bang.  Here is the end of crankshaft once the clutch has been removed.  The shaft is machined with a slight taper that matches the tapered hole on the clutch.  It always seems amazing to me how all the torque from the engine is transferred by the friction on those two tapered surfaces.

No comments:

Post a Comment