CLUTCHES THAT SEPARATE
When a customer comes in with a clutch that has separated (the sleeve is removed from the hub) or the outside snap ring has been forced off the sleeve, there are several questions to ask to determine what caused the problem. Unless THEY correct the problem, it will repeat itself.
- 3/16″ key should only be ½” (.500) long. A standard ¾” long key will fit in the clutch but because of the taper in the keyway it will prevent the clutch from fitting fully on the shaft. File or sand the key so it slides easily in the keyway, you don’t want to force it in.
- Crankshaft has to be a minimum of 2.30″ long. This is the standard length for most Briggs, Tecumseh and Honda engines. But there are short crankshafts used on rototillers and mini-bikes that will not fully support the clutch. This short shaft will eventually pull the clutch apart- either at the hub and sleeve or at the snap ring area.
- Clean the crankshaft with emery paper prior to putting on the clutch. The burrs on the crankshaft cause the clutch to be hammered on. Hammering on the clutch will ruin the snap ring area and will put undo pressure on the bushing, causing it to wear prematurely. If we cannot get the drum off the sleeve portion of the clutch, we know it was hammered when mounted.
- When aligning the clutch sprocket with the rear sprocket, the engine must be moved front to back to put tension on the chain or from side to side to get proper alignment. The wheel containing the mounted sprocket can also be shimmed in or out. NEVER USE THE CLUTCH for alignment – a clutch cannot take a side load for a very long time without causing damage to the clutch.
- The only time you should use set screws to hold a clutch in place is if the crankshaft is not drilled and tapped. All kart manufacturers have switched to a drilled and tapped crankshaft and only on older models will you have to use set screws. When ever possible hold the clutch on with a bolt and washer. Never use the set screws because you WANT the clutch to float on the shaft to self align with the rear sprocket.