What Clutch Should I Run With My Big Horsepower Motor?
By Jason Van Wyhe
Clutch slipping or wearing out too fast in your belt drive? Building a bike and want to get it right from the start?
One of the best all around solutions is the Rivera Engineering Pro Clutch. Rivera Pro Clutches come standard in Primo belt drive kits, including the Brute III, IV, and V. The Pro Clutch is also available for stock bike applications, including Harley Davidson Softails, Dynas, Sportsters, Shovelhead, Panhead, and Knuckleheads.
The advantages of the Pro Clutch over a standard spring clutch are twofold. First, Pro Clutches are built heavy duty for big horsepower applications. Rivera Engineering has one of the best names in the aftermarket motorcycle business, and this product is one of the reasons why. It uses a custom hub with a special bearing setup that installs directly into the clutch basket that is much more durable than a stock setup. The clutch plates have a larger surface area, which provides a huge increase in grip. Overall, the unit is very solid.
The second advantage the Pro Clutch has is that it is actuated with Diaphragm clutch. Most motorcycle clutches are spring-tension clutches, meaning there are 4-10 heavy duty coil springs that apply pressure to various points on the pressure plate, which then applies pressure to the plates and steels. The problem is you have to have the exact same tension on each spring or some points on the clutch will grip more than others. Conversely, a diaphragm clutch uses a single large "diaphragm spring", which is cup-shaped rather than coiled. The big advantage of this is that pressure is applied evenly over the whole surface of the pressure plate, and pressure only has to be adjusted on this one spring. A side benefit is that diaphragm clutches are much easier to actuate that spring clutches.
Harley Davidson liked this design so much they devised a their own diaphragm clutch in 1990. The Harley version isn't nearly as stout performance-wise as the Pro Clutch, but it was a big improvement over their previous spring clutches.
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