Silvercliff.com/Bigsnow Tech Pages Secondary Clutch and Wheel Bearing Service

Tech Section Bleeding Your Snowmobile Engine Oiler Change a Belt in Under a Minute Track Removal Secondary Clutch and Wheel Bearing Service Belts and Clutch Tuning Suspension Tear Down Fuel Dyno Testing

I am working my way though the sled in preparation for winter. Today we have more easy stuff, checking out the secondary clutch and the back axle bearings. The secondary is usually really easy to service, so there isn't much reason to avoid it. Most of the time it comes off with one bolt, and it is easy to get to. As far as tools, the only specialty tool you will likely need is a large reversible snap ring pliers. These are available at any auto parts store for under $10. Assuming that you read "How to change a belt in under a minute" last year, you should be able to peel the belt right off and you are ready to pull the clutch. A single bolt on the side of the clutch secures it to the cross shaft. Hit the brakes and remove the bolt. The clutch should slide right off of the shaft. As long as you are right there, clean the shaft and apply a fresh light coat of Never-seize. If it is rusty, use a wire wheel to clean it up first. This will assure that the clutch will come off next time too. Also take a look at the cross shaft bearing. They are easy to check and replace, and they take a lot of abuse, so they need occasional replacement. I will cover more about bearings later in the report.  Once you have the clutch off and up on the bench, get your snap ring pliers out and remove the ring. A good quality, properly sized snap ring pliers will save a lot of frustration here. Just buy the right tool, it is $10 or less. Wear safety glasses, these rings, or parts of them, can fly forcefully. Once you remove the snap ring, the helix should pop out under the pressure from the spring. Keep a hand on the helix to make sure it is a controlled process. The helix is one of the keys to the secondary clutch. Check the ramps for wear and scoring as well as the inner bore and bushing surfaces. This one shows minor wear considering I put it in 3,600 miles ago. I cleaned and degreased everything, and polished the ramps and bushing surfaces. The helix and bushings were intended to be run dry. Putting grease or oil on here seems like a natural, but it is not what you want. Dirt gets into the grease, and it becomes an abrasive paste accelerating wear. Check all of the surfaces that run against a bushing and the ramps. If there is light corrosion you can wire wheel it or use 600 or 1000 grit sandpaper to polish it up. If it is too bad or worn, replace the helix. I have seen multi angle helixes as cheap as $35. After checking over the helixes, I took a look at the sheaves. The center post needed a little clean and polishing and a cleaning and check of the bushing that runs on it. . The belt surfaces showed some corrosion, but I didn't spend too much time on that. You can polish the sheaves up to keep them from getting too rough, and the belt will clean that up in the first 5 miles. In this case, the sled has seen 4 summers of outside storage, and corrosion is on everything. I have been cleaning everything as I go, and I have a rag with a combination of synthetic waterproof grease and carb cleaner on it. It leaves a protective film without leaving everything greasy or prone to attract dirt. All of the parts got cleaned with carb cleaner and compressed air and hit with the protective film. Inside the sheave that houses the helix, there are two more bushings to clean and inspect, and the buttons that run on the helix. I checked for abnormal wear on the bushings to see if it is side loading and the buttons get a look too. Buttons are cheap, replace them if you are inside the clutch and they show wear. Once everything is cleaned up, I put the two sheaves back together and check a few things. The first is to check the bushings to see if they feel sloppy. The second is to check that the sheaves can turn and spread without binding. You are checking bushing #3 in the picture above. What hole do I put the spring in? There should be wear in the one that it was in. You can chose a different hole if you want to change backshift and upshift characteristics of the clutch. You will want to check your spring for warping and general fatigue. If it feels weak, it probably is. It was the source of a lot of boggy sleds when I was servicing them. Again, springs are fairly cheap, and if yours is worn, an new one will make a night and day difference in your sled's performance. I also know that one of the Minnesota brands had a batch of weak springs in the early-mid-90s, and there was a service bulletin on them. It was a standard procedure to check them as described below, and it only takes a minute. As you reassemble the helix, you will have some pushing and turning to do. Push the helix part way down and turn it to tighten the spring until the buttons ride the next set of ramps, then push down and clip it. That preloads the clutch spring. Double check the clip to make sure it is fully seated in the groove. It is easy to not have it in all of the way if the spring pressure is on it when it is installed. Roller secondaries are a little different in configuration, but the procedure is similar. Pull it apart, clean it up, and check the helix ramps, bushing surfaces and rollers for wear. So, I have checked out the cross shaft bearing, cleaned up the shaft and never seized it, and mounted the clutch back on the shaft. Before I put the belt back on, one more test. This tip alone is worth reading the whole page. Turn the clutch so that the balancing holes are up. Locate a drill bit about the right size, and put the chuck end in one of the balance holes. Take a fish scale and hook it to the bottom of the drill bit, hold the other sheave and pull. The clutch sheave should not turn before about 12 pounds. Don't go too high on the drill bit, the extra leverage will give a false reading. This is an easy test and an important one. A weak secondary spring will make your sled a real pooch.