Typically, riders will know when it’s time to freshen up the clutch in their dirt bike or ATV, if not by tracking maintenance intervals, then by experiencing problems with engagement and or an inconsistent feeling in the lever. These symptoms are commonly attributed to needing new clutch plates and fibers, but what can easily be overlooked is the clutch basket.
When assembled, a clutch pack is stacked within the basket. The protrusions of the clutch fibers slide in between the “fingers” or “tangs” of the clutch basket. When the clutch is disengaged, the friction between the clutch fibers and the steel plates mated with the inner hub allow the power from the crankshaft to successfully be transferred through the clutch, to the input shaft, and eventually to the rear wheel. During this process, the clutch fibers apply force against the sides of the basket tangs. However, clutch basket tangs are not only responsible for this this axial transfer-of-power force, they are also subject to lateral force as the clutch pack moves outward and inward with clutch engagement and disengagement.
Due to these different forces applied to basket tangs, wear marks and notching can begin to form along the sides of the tangs. The severity of this wear will vary based on total run time, clutch use practice, and several other factors. Subtle, darker wear marks on are not necessarily of major concern, but once the marks turn to notching and can be physically felt with a pick or fingernail, potential for problems begins and the basket should be replaced soon to prevent getting to the point of breakage.
It’s worth it to note that this type of wear is most common for cast aluminum baskets, which are used in most Honda, Yamaha, Kawasaki, and Suzuki dirt bike and ATV models. Late-era KTMs are equipped with steel baskets that are much more resistant to notching. Therefore, if your machine is equipped with an aluminum basket and you’re ready for a replacement, choosing an aftermarket replacement constructed of stronger material and more wear resistant features will ultimately give you the most hours for your buck over going with an OEM basket.
Because Wiseco does all their own forging in-house, Wiseco’s clutch baskets are the only ones offered with forged construction instead of billet. Wiseco forges an aluminum puck into a bowl-like shape first, then does all the CNC finish machine work. This allows the grain flow of the alloy to align with the shape of the basket tangs, greatly increasing tensile strength. Topped off with a hard anodize treatment and Teflon coating, Wiseco clutch baskets are so wear resistant that they come with a lifetime warranty against notching and breakage. Plus, the coatings make for a very smooth pull in the lever.
So, you’re ready to get rid of your old, worn clutch basket and fit a new one. With the basket out of the bike, this process consists of removing the starter gear, clutch-driven gear, dampers, backing plate, and screws/rivets from your old basket and fitting the two gears onto the new basket along with new dampers, fasteners, and a new backing plate.
What’ll Help you Get the Job Done
- Hydraulic press or vice
- Center punch, drill/drill press and appropriately sized bits (or alternative equipment to remove rivets)
- Torque wrench
Clutch Basket Replacement Process
New Wiseco clutch baskets come with new rubber dampers, a new backing plate, fasteners treated with Loctite, and a hex bit to tighten the fasteners. Therefore, the only components you should be reusing when prepping your new clutch basket to go in the bike are the starter and drive gear.
Step 1: Removing the Rivets
There are several methods to removing rivets that are also dependent on the tools you have available. Our preferred method is a drill press to help ensure precise removal of the rivets without damaging either of the gears that need to be re-used.
Before beginning drilling, punch a locating hole using a simple hammer and punch in the center of each rivet holding the backing plate to your old basket. This will help keep the drill bit guided in the center of the rivet when you begin drilling.
Once all your locating holes are drilled, begin drilling out the rivets one at a time, drilling from the back side of the clutch basket. Be sure to choose a drill bit that is slightly smaller than the rivet so you don’t damage the fastener holes of the starter gear.
Step 2: Remove the Backing Plate and Starter Gear
Once all the rivets are removed, the old backing plate and the starter gear can simply be lifted off your old basket. A small amount of hand force maybe required when removing the starter gear, as the rubber cushions are holding it in place.
Step 3: Press out the Drive Gear
The remaining gear still fitted in your old basket is the drive gear. This gear is pressed-in and held with an interference fit in the center of the basket with teeth on the gear that align with grooves in the basket. Our preferred method to removing this gear is with a hydraulic press. If you don’t have a press, a bench vice can typically be substituted.
Whether you’re using a press or a vice, using proper fixturing and spacers to hold the basket in place and press out the gear is crucial to be sure you don’t damage the gear itself. Before you begin applying force, double check your fixturing and spacer sizing to ensure safe removal.
Once you’re confident in your setup, simply apply force until the gear is free from the old basket. These gears are typically not exceptionally tight, so if you’re having trouble getting movement, double check that you’re pressing straight through and not accidentally applying lateral force.
Many applications will have a spacer that goes along with the drive gear. Be sure not to misplace that spacer, as you’ll need to reuse it.
Step 4: Install the Drive Gear into your New Clutch Basket
To install the drive gear into the new clutch basket, using a press or a vice can be avoided by using a combination of heat and chilling. Heat up your new clutch basket by setting it on a hot plate. Using a torch is also an option, but use caution as torches make it easy to apply too much heat. Heating up the basket causes the alloy to expand, making it easier to insert the new gear.
While the basket is heating up, place your gear in a refrigerator or a freezer to chill it. This causes the material to contract, making it slightly smaller and easier to drop into the basket.
Once the basket is sufficiently heated (use proper gloves, it will be too hot to touch) and the gear is chilled, flip the basket over to the back side. Slide your spacer/washer (if applicable) onto your gear, then carefully align the teeth of the gear with the grooves of the basket, allowing it to drop into place. The gear should simply fall into place with no additional force needed. Once the basket and the gear return to normal temperatures, the material of each will return to normal properties and the gear will be interference fit and secured in the basket.
Step 5: Install the Starter Gear, Cushions, and Backing Plate
To install your existing starter gear on your new basket, begin by simply setting it on the back side of the basket in the same orientation in which you removed it from the old basket. Gears will vary by model, but most have a specific side that should be facing the basket.
Next, install new, rubber cushions (included with the Wiseco clutch basket), aligning them within the openings of the starter gear and fitted around the stand-offs on the back of the clutch basket. These cushions are not symmetrical, so be sure to install in the same direction they were removed. Reference your owner’s manual if needed.
Once all the cushions are properly installed, place the new supplied retaining plate over the starter gear and cushions, aligning the holes with the threaded stand-offs of the basket, and secure it with Loctite-treated fasteners (new plate and fasteners also included with Wiseco basket). Tighten down the fasteners and torque them in a star pattern to ensure evenly distributed clamping force. Always reference your supplied basket installation instructions or your owner’s manual for the torque specification on the fasteners. Models that came equipped with a riveted basket will not have a torque spec supplied, so be sure to reference the installation instructions. Wiseco clutch baskets typically call for 80 in-lbs, but can vary depending on the application.
Once everything is secured and properly torqued, flip the basket over to access the inside of it and peen the ends of the fasteners. This process is simple; using a hammer and a punch, place the punch at the edge of the bottom of the fastener and aim it toward the edge of the threaded basket hole. Give it one firm strike with the hammer to push the material against the basket. This provides extra protection against the fastener backing out of the basket.
And that’s it! After you’ve completed all the above steps, you’re ready to re-install the clutch basket in your engine via the process outlined in your owner’s manual.
To enjoy the full package of protection and performance, Wiseco also offers forged inner hubs and pressure plates, as well as clutch pack kits, all working together to provide smooth, consistent, long-lasting clutch performance.