Clutches are prone to routine beatings and need to be checked and maintained on a regular basis. Clutch parts wear at different rates depending on the rider’s style and riding conditions. Here are a few basic tips that anyone with a torque wrench can easily handle.
1. Let’s look under the hood: Start by either draining the engine oil, or laying the bike on its side (if you prefer to change the oil after working on the clutch). Drop the rear brake pedal by removing the allen screw holding it in place. Remove the clutch cover bolts and pop the clutch cover off. Careful not to damage the gasket.
2. Remove the center clutch screws and springs. You can now remove the pressure plate and access all the clutch fibers and drive plates.
3. Inspect the clutch fibers and drive plates. The service manual will give you minimum thickness specifications. If the plates are black and visibly shot, play it safe and replace them. The steel drive plates can warp when overheated. Inspect them for warpage by laying them on a flat surface such as a piece of glass.
4. Inspect the clutch basket for notches on the sides of the tangs. A well maintained basket should have smooth tangs. Notched tangs inhibit smooth clutch operation and can keep the clutch from functioning properly. The die cast aluminum baskets wear easily. Investing in a good aftermarket clutch basket will improve clutch feel, extend basket life, and improve oil flow through the clutch. I am a personal fan of the Wiseco baskets since they are forged instead of machined from billet. Forgings are tougher and lighter than billet parts due to grain flow in the material that is aligned to the features of the part. (Read more about changing the clutch basket in the clutch basket article – coming soon.)
5. Inspect the inner clutch for notches on the sides of the drive splines. Like the clutch basket, the inner clutch can become notched after time. If the drive splines are notched badly, replace the inner clutch. The OEM inner clutches are relatively inexpensive, but aftermarket inner clutches like the Hinson will offer the same benefits as an aftermarket clutch basket.
6. If either the clutch basket or the inner clutch need replaced, you will need to remove the center nut from the transmission shaft that holds the inner clutch in place. An impact wrench works best for removing this nut. However, if you don’t have an impact wrench, you will need a special tool to hold the inner clutch while you remove and install the center nut. DO NOT jam something in-between the inner clutch screw bosses to try and hold it. They WILL break off.
7. Assemble the clutch by first putting the basket on the shaft. MAKE SURE it drops down onto the shaft all the way. There are 2-3 gears that have to line up with the back of the clutch basket, so make sure everything meshes and the basket drops all the way onto the shaft. A splined washer goes on next, and then the inner clutch hub. The retainer washer goes on after the inner clutch, and finally the retainer nut. While holding the inner clutch with the special holding tool, torque the center nut according to the torque spec in the service manual. (I usually snug the nut back on with the impact wrench, but this is NOT recommended, as you run the risk of over torquing and stripping the nut/shaft.)
8. Soak the new clutch plates in oil and then install them into the clutch. Always start with a fiber, and then alternate steel, fiber, steel, fiber, until you end with the last fiber. The clutch plates should stack up to about the same height as the top of the clutch basket.
9. Return the lifting post to its proper location in the end of the transmission shaft. Then install the pressure plate, followed by the clutch springs and bolts. Torque the spring bolts to the proper specification.
10. Install the clutch cover and torque the bolts to the proper spec. Lastly, install the brake pedal.
11. Ensuring the clutch cable is adjusted properly can have a large effect on the life span and operation of the clutch. The general rule is a “nickel’s” worth of play at the lever.
Maintaining a clutch is not very complicated, but can have huge benefits to ensuring your ride or race is fun and trouble free. Torquing all the bolts according to the specs in the service manual is the most important step. Buy a good torque wrench and go for it!