In the busy world today, fewer of us are taking the time to adjust the deflection of the drive belt on our snowmobiles. However, even with the new drive belt compounds that last so very long, you should adjust the belt deflection after the first 150 miles (new sled or new drive belt) and then every 1,500 miles thereafter. This is a generalization, but comes straight from the factory engineers as what they believe to be the best maintenance schedule for drive belt deflection adjustment.
Why are we checking belt deflection? Because the exact nature of how the clutches and drive belt interact is a critical component of the shift pattern of the clutch system on a snowmobile. The drive belt width and length pretty much dictates how it is going to fit into the clutches, and as the drive belt wears (narrows) it drops down into the secondary clutch but also makes the primary have to close a wee bit further before it engages (grabs) the drive belt. It all effects the gear ratio at which the engine is asked to move the machine.
Most sleds have a simple adjustment procedure of setting the sheaves on the secondary, bringing the sheaves closer together as the belt narrows to keep it riding at the top of the sheaves at engagement. Check your sled’s owners manual for the exact adjustment procedure for your exact style of secondary clutch. Whatever you do, please check it as it really does have a huge effect on how your sled takes off and shifts. It is also a whole lot less expensive than simply installing a new drive belt every time the old one starts to narrow slightly!
Truth be known, if it is time to check your belt deflection it is also a good time to clean the clutches and check for sticky flyweights or rollers (in the primary). Even if all you do is take a blow gun attached to an air compressor and blow the residue out of the clutch, this will go a long ways to help keep it clean and working properly. Of course, complete disassembly, cleaning and inspecting all of the bushings and wear surfaces is always the best route, but this does take special tools and knowledge to do so safely, and only you know if you have the training and tools to do so. Safely. Properly. If not, take it to a professional. Do it every couple thousand miles, or do not be surprised when the whole thing starts to shift sluggishly when you need it to be shifting smoothly – usually right after a fresh snowfall, and your sled bogs because it is in too high of a gear for the conditions and doesn’t backshift (downshift) properly. Sucks to be you when that happens!
From the November 2015 issue of SnowTech Magazine. (September 2015)
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