EVERYTHING YOU NEED TO KNOW ABOUT CLUTCHES
Your clutch is a very important component of your ATV. It transfers the engine’s power from the crankshaft to the transmission. There are two main types of clutches on today?s ATVs, automatic and manual. The clutch system you need to pay close attention to is a manual clutch. This system works well and can handle lots of horsepower; however, they require maintenance and sometimes replacement.
HOW DOES A MANUAL CLUTCH WORK?
Manual clutches have a stack of plates locked together under spring pressure. Two types of plates are used (fiber and steel) and installed in an alternating order, starting and ending with a fiber plate. The steel plates are driven by a hub that is connected to the engine?s crankshaft. The fiber plates drive a basket and gear that connects to the transmission. When the clutch is engaged (lever out) and working properly, the spring pressure holds the plates together, forming a link between the engine and transmission. When the lever is pulled the spring pressure is relieved from the clutch plates. Power can no longer flow through the clutch with the plates apart. All of this is done spinning in a bath of engine oil that cools and lubricates the plates.
Both two and four-stroke engines use oil to cool their clutches. However, they do have their differences. Two-stroke engines use transmission fluid to lube and cool the gears and the clutch. Four-stroke engines use motor oil that cools the transmission, clutch, rod, crank and bearings. This means four-stroke oil generally gets hotter and requires more frequent oil changes. Regardless of your engine type, changing the oil often is a good maintenance practice and cheap insurance.
Two and four-stroke engines also require a different clutching technique when riding. Top ATV racer Kory Ellis regularly switches between the two powerplants for certain events and explains the differences. “Off the line and when shifting I use the same technique with both motors. “The big difference is when exiting corners; the four-stroke usually has enough torque to pull strong out of corners. The two-stroke engine takes a lot of clutch feathering to keep the motor revving in the meat of the power band. I use the clutch in tight technical sections and sometimes before approaching jumps to get my speed up.”
WHAT ARE THE SIGNS OF A FAILING CLUTCH?
If you ride your quad in severe conditions such as hill climbing, mud, sand or racing situations, your clutch is probably getting abused. Signs of an abused clutch are 1) Shifting under power is difficult and neutral is hard to find. 2) The machine still moves forward with the lever pulled in. 3) In gear, the engine revs high and the vehicle barely moves. 4) A putrid burning smell seeps from the engine. 5) The lever is hard to pull.
WHAT ARE THE FIXES?
The first three could be as simple as the free-play not being adjusted properly. With the engine cool the amount of space between the lever and clutch perch should be 1/4- 3/8 inches. Remember there may be a place on both ends of the cable for adjustment. Another cause for problems one an two could be warped discs or a grooved clutch basket. The fiber “drive” plates have ears on them and slide in notches in the basket. Eventually these ears create grooves and stick. Signs three and four are caused when the clutch has been fried and the plates are worn, burnt or the springs may be have lost tension. A clutch can get burnt by slipping the clutch or having it improperly adjusted. Time to replace them. Problem five is either caused by notches in the basket or a dirty, dry cable. Your clutch cable should be lubed on a regular basis. Boss recommends a product called Dri-Slide for the cable and its pivot points. A soft lever feel can be caused by worn springs. The springs should be replaced at the same time as the plates. A complete clutch rebuild package including springs, fiber and steel plates run about $100-$150 for OEM parts and $80-$120 for aftermarket parts. New cables run about $25.
Next to the plates, the basket has typically been the weak link in a clutch system. In addition to grooving, the basket can break. You increase the risk of a basket failure after engine modifications have been made. Stock baskets are usually made of cast aluminum and are not engineered to handle much more than the stock horsepower of a certain machine. After years of racing and countless numbers of broken baskets, Wayne Hinson developed the Hinson Racing Billet Clutch Basket. Virtually all of the top quad pros use the Hinson basket.
WHY IS A HINSON BASKET SO GOOD?
Hinsons Billet Basket is made of T-6 aircraft quality aluminum and has a special Akadizing process applied to it. The basket is virtually unbreakable and Akadizing gives the aluminum a finish that allows the clutch plates to slide better. Also, the ears of the basket have a window in them for better oil flow and cooling. Hinson Baskets are priced at $225.