How to Replace a CV Boot on Your 1998 Yamaha Bigbear 350 2X4 Utility ATV
Shop parts for a 1998 Yamaha Bigbear 350 2X4 ATV.
Understanding Rear Boot Failure on a Utility ATV
CV boots on the 1998 Yamaha Bigbear 350 2X4 take more stress per operating hour than most owners account for. Every hour of work use—hauling a loaded dump cart, running a plow, or navigating deep field ruts—flexes the rear axle boot through its fold range repeatedly under load. The boot is clamped at both ends of the CV joint and must flex continuously while maintaining a watertight seal against the specialized CV grease inside. Rubber that ages past its service window loses this ability gradually, hardening at the fold lines first, and eventually cracking under the flex loads it previously handled without issue.
On the Bigbear 350 2X4, physical damage from rocks and debris is as common as age-related failure. The inner boot at the differential end of the rear axle is positioned close to the ground and exposed to anything displaced during field or off-road work. A single sharp rock can puncture a boot that was otherwise in serviceable condition, and the resulting grease loss starts with the first flex cycle after the puncture. Either failure mode puts the CV joint behind the boot on a wear timeline that accelerates with every subsequent ride.
As a 2WD utility ATV, the Bigbear 350 2X4 drives only the rear wheels. The CV boots are located on the rear axle only—the front wheels steer and roll freely without a driven axle, so this service is rear-focused.
Identifying Boot Damage Early
A failed CV boot on the 1998 Yamaha Bigbear 350 2X4 typically shows itself through grease deposits near the rear axle before producing any noise. The spinning axle distributes CV grease onto the inner wheel, the rotor face, the brake assembly, or the adjacent frame when a boot tears. This pattern is distinctive—CV grease is thick, tacky, and dark—and builds up with each ride. Any time it appears near the rear axle of the Bigbear 350 2X4, schedule an inspection before the machine goes back to work.
Remove the wheel and examine each boot by hand while rotating the axle. Look and feel for splits, cracks, clamp gaps, and grease on the boot exterior. The fold areas and the zones just inside both clamp bands are where damage appears first. A boot that looks intact but feels stiff or cracked at the folds should be replaced before it opens fully. A clicking or knocking from the rear axle during power turns or under acceleration is a sign that joint wear has already begun and the boot has been compromised long enough to allow contamination inside.
On the Bigbear 350 2X4, CV boot service is rear-axle work. The front wheels are not driven and have no CV joints to service on this machine.
Setting Up Before You Start
Before pulling hardware on the 1998 Yamaha Bigbear 350 2X4, stage: floor jack and jack stands; correct-size axle nut socket for the Bigbear 350 2X4; calibrated torque wrench; snap-ring pliers; boot clamp installation tool; and shop rags. The boot kit must include the boot, both clamp bands, and the correct quantity of CV grease. CV grease is a specialized compound designed for the angular velocity and contact pressures inside a CV joint—typically a molybdenum disulfide formulation that maintains a lubricating film under conditions standard grease formulations can’t handle effectively.
Work over a drain pan. Contaminated grease from a torn boot acts as an abrasive in the joint and needs to come out completely. MotoSport.com carries CV boot kits and axle assemblies for the Bigbear 350 2X4.
Wheel and Axle Disassembly
Get the 1998 Yamaha Bigbear 350 2X4 on jack stands and remove the rear wheel. Pull the cotter pin, remove the axle nut, and push the axle spline inward to separate from the hub. Use a hub puller if the Bigbear 350 2X4 has a tight fit. Release the inboard snap ring at the differential with snap-ring pliers and pull the axle free. Set it on a clean surface, cut the clamp bands, and slide the torn boot free. Before installing the new boot, clean the shaft surface and both clamp groove areas on the Bigbear 350 2X4—grit in the groove prevents proper clamp engagement.
Joint Inspection Before Reassembly
Once the boot is off the 1998 Yamaha Bigbear 350 2X4, wipe old grease away and work the CV joint through its full articulation—compression to extension and full angular rotation. The joint should feel smooth and consistent throughout. Roughness or resistance at a specific angle signals race or ball wear. Hold the shaft and try to move the outer housing side to side and axially beyond its normal articulation. A serviceable joint has firm, controlled movement with no rattle. Any looseness or clunking in the Bigbear 350 2X4’s joint outside its designed range means the axle assembly needs replacement before a new boot goes on.
Repacking and Fitting the New Boot
Before repacking the 1998 Yamaha Bigbear 350 2X4, remove all old contaminated grease from the joint’s housing, balls, and races. Thread the replacement boot onto the shaft before reassembling the joint. Work the CV grease from the Bigbear 350 2X4’s kit in by hand and rotate the housing to distribute it through all the bearing cavities. Use the complete quantity. Position the boot with both ends in the clamp grooves, crimp both clamps to full engagement, and tug each one to confirm it won’t rotate. MotoSport.com carries CV boot kits for this ATV.
Axle Reinstall and Post-Job Check
Seat the inboard end in the differential on the 1998 Yamaha Bigbear 350 2X4 until the snap ring clicks—a pull test should show it locked. Guide the outboard spline into the hub, thread on the axle nut, and torque to the Bigbear 350 2X4’s specification. Install a new cotter pin or re-stake as required. Reinstall the wheel and torque the lug nuts. Lower the Bigbear 350 2X4 and move the rear suspension through full travel to verify boot clearance. A short test ride completes the job. MotoSport.com carries CV boot kits and axle assemblies for this ATV.
Related Shopping Categories
Shop CV Joints for a 1998 Yamaha Bigbear 350 2X4 ATV.
Shop Axles for a 1998 Yamaha Bigbear 350 2X4 ATV.
Shop Lubricants & Solvents for a 1998 Yamaha Bigbear 350 2X4 ATV.
Shop Wheel Bearings for a 1998 Yamaha Bigbear 350 2X4 ATV.
Shop Skid Plates for a 1998 Yamaha Bigbear 350 2X4 ATV.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your ATV's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.
