shifting gears

Full Shift Out Problems
I often hear guys complain that they can't get the belt to come all the way up on the driving sheave. Many use a black marker on the sheave, and by looking at what's left after a little running, they can determine how high up the belt came. If the machine is geared 10% higher than it will ever run, the belt will never get to the top. To get the belt to reach the top, you would have to lower the gearing.

You may, however, have run into a genuine assembly problem that will not permit the belt to shift all the way out, and some of these can cause serious belt breakage problems. If your secondary does not open all the way up but stops short of a full shift, the belt is not going to shift all the way out. What will happen next is that the engine will over-rev, and as the flyweights put more force on the belt, it may stretch and actually snap. You do not want the secondary to stop shifting before the front clutch reaches the end of its travel, because of the extra stress this puts on the belt.

Another source of insufficient shiftout may be springs that have been shimmed so much that they coil bind before the clutch is shifted fully out.

Yet another source of problems can be that the locknut holding the spider is too long and touches the cover bushing before the belt is all the way to the top. Grinding this locknut shorter will cure the problem. An even worse condition occurs when the front clutch actually travels too far and pushes the belt all the way out of the sheaves. The belt may then flip over and lock up the transmission and the track at top speed. This may occur if the spider has been spaced incorrectly for a wide belt application.

On some clutches, the sheaves may touch each other on the bottom before the belt is all the way to the top. The cure for this is to machine small flats on the bottom of the sheaves to make them go together further. Again, caution is required to prevent the belt from shifting too far out. To make sure everything is in order, we often assemble the two clutches in the machine without the springs. We then install the belt and move it out to the full shift out position. This allows you to see where you may have interference problems, and to work out a solution.

Thanks to the chain case and the ability to change ratios, you can custom tune your machine to your own driving style, the driving conditions in your area, and gain maximum efficiency from your engine and drive train. I don't think anyone is willing to give up this flexibility anytime soon.