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.

Arctic Cat 1000 TRV H2

A friend brought over an Arctic Cat 1000 TRV H2 with a broken drive belt.  This is Cat's big top of the line ATV, with a twin cylinder 1000 cc motor, two up seating and all the fancy extras.  He had already purchased a spare belt and I thought that it would be a quick easy job.

When I pulled the belt cover off and removed the debris from the old belt I found a small piece of plastic and a metal key for a shaft.  Obviously there was more trouble than just a broken belt.  I removed the secondary clutch and discovered that the helix was cracked.

This first photo shows the clutch on the work bench with an improvised setup to compress the spring.  I used a piece of all thread and a few metal scraps to compress the spring enough to remove the snap ring.

Here is the broken helix.  You can see that the part cracked right at the corner of the groove for the keyway.  This is a classic example of a failure at a stress concentration.

This machine has a powerful engine on a large and heavy chassis, I wonder if the Arctic Cat engineers did not design a drive system that is tough enough to handle it?

Yamaha Grizzly 550

Someone brought a Yamaha Grizzly 550 ATV over for me to look at. They said that it made a bad grinding sound and became very hot when they drove it.

I took a look at it and noticed that the top of the engine was covered with black dust. This machine, like a lot of newer ATV's, uses a belt drive CVT similar to the drive train on a snowmobile. On closer inspection the dust looked like the residue from a worn out drive belt. I took the cover off the clutches and discovered that a bolt had come loose and had been rattling around inside the cover. The belt was destroyed and the clutches are beaten up pretty bad.

The machine will need a new belt and I am going to recommend to the owner that the primary clutch be replaced. There is not much labor in this job, but the new clutch will be expensive.

Interestingly, this is the third Yamaha with clutch problems in the village in the last few months.

C.O.