Rebuilding a 300 Hirth into a MOD motor
A couple more pics of the HD. All the brass parts were polished and the bottom plates were shined up a little bit with a "scotch-brite" buff on a die grinder.
Here is the Salsbury clutch with the "Hi Rev" kit rollers and springs. * * * Because this clutch is a newer version that uses the small diameter springs, some modifications had to be done to work with the older springs. On the right side you can see the unmodified spring stop and on the left side you can see how much was removed.
Here you can see both sides cut back. This had to be done on all three sides. If you are careful and remove the same amount from each spring stop, the balance will not be affected. The inside edge of the flat area between the spring stop and the center pin mount also had to be filed at an angle to keep the springs from binding. * * * Here are the "Hi Rev" kit parts.
The rollers are marked with yellow and measure .803" (20.39 mm) in diameter. Each roller arm assembly weighs 2.1 oz (59.33 g) * * * The springs are plain steel and use .117" (2.97 mm) wire.
The springs have six coils and are made from a slightly thicker wire. * * * Here we can see the parts installed and ready for the springs to be hooked onto the roller arms.
The springs are all hooked up and the assembly is ready for the ramp plate. Next to the clutch is my home-made spring tool. This is a "must have" tool if you are working on Salsbury clutches. * * * On the right is the correct ramp plate for the MOD clutch with it's new coat of paint. On the left is a stock ramp plate. The paint is Valspar Metal series, and the color is Graphite (with a coat of Hi-Tech clear). This color is almost perfect for getting a "restored but stock" look on the older Salsbury ramp plates.
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