Replacing a Torn Rear CV Boot on the 1993 Yamaha YFM350ER MOTO-4
Shop parts for a 1993 Yamaha YFM350ER MOTO-4 ATV.
What Damages the Boot on the YFM350ER MOTO-4
The CV boot on the 1993 Yamaha YFM350ER MOTO-4 protects the rear axle CV joint from the contamination and grease loss that lead to joint failure. On a utility ATV used for hauling, plowing, or trail work, the boot faces more demanding conditions than a recreational machine would see in equivalent operating hours. Deep mud crossings coat the boot exterior with abrasive material, water submersion tests the clamp seals, and sustained low-speed torque loads during work use cycle the boot continuously through its flexing range. The boot must maintain a sealed environment for the CV grease packed inside the joint through all of these conditions.
Age and UV exposure are the most consistent failure causes on the YFM350ER MOTO-4. The rubber compound hardens over time, losing the flexibility it needs to flex at the fold lines without cracking. A boot that appears intact on a visual check may be brittle enough at the folds to crack during a cold-morning ride when rubber stiffens in low temperatures. Physical damage from trail debris is equally common on a utility machine—the inner boot at the differential end of the rear axle sits close to the ground and is directly in the path of anything the rear wheels kick up during field or trail work.
As a 2WD utility ATV, the YFM350ER MOTO-4 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.
Symptoms of Boot Failure to Watch For
The clearest evidence of a torn CV boot on the 1993 Yamaha YFM350ER MOTO-4 is grease deposited on a surface near the rear axle. Once a boot tears, the rotating axle slings CV grease onto the inner face of the rear wheel, the brake rotor or drum, the caliper, or the frame rail adjacent to the axle. CV grease is thick, dark, and adhesive—it coats surfaces differently than mud or brake dust and accumulates with each ride. Finding this on the YFM350ER MOTO-4 near the rear axle is enough to stop work and inspect before continuing.
A hands-on inspection with the wheel removed confirms the damage location and extent. Raise the YFM350ER MOTO-4 on jack stands, remove the wheel, and work each boot by hand while rotating the axle. Feel and look for any tear, crack, puncture, or gap at a clamp edge. The fold lines and clamp transition zones are the highest-stress areas. A boot that shows surface crazing or feels hard and inflexible at the folds should be replaced proactively. A clicking or popping from the rear axle during acceleration or tight turns indicates joint wear has begun—the inspection needs to evaluate the joint at that point, not just the boot.
On the YFM350ER MOTO-4, CV boot service is rear-axle work. The front wheels are not driven and have no CV joints to service on this machine.
Tool and Parts Checklist
Before pulling hardware on the 1993 Yamaha YFM350ER MOTO-4, stage: floor jack and jack stands; correct-size axle nut socket for the YFM350ER MOTO-4; 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 YFM350ER MOTO-4.
Axle Removal and Boot Access
Get the 1993 Yamaha YFM350ER MOTO-4 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 YFM350ER MOTO-4 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 YFM350ER MOTO-4—grit in the groove prevents proper clamp engagement.
Evaluating the Joint After Boot Removal
Once the boot is off the 1993 Yamaha YFM350ER MOTO-4, 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 YFM350ER MOTO-4’s joint outside its designed range means the axle assembly needs replacement before a new boot goes on.
Grease, Clamps, and Reassembly
Before repacking the 1993 Yamaha YFM350ER MOTO-4, 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 YFM350ER MOTO-4’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.
Final Assembly and Function Test
Seat the inboard end in the differential on the 1993 Yamaha YFM350ER MOTO-4 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 YFM350ER MOTO-4’s specification. Install a new cotter pin or re-stake as required. Reinstall the wheel and torque the lug nuts. Lower the YFM350ER MOTO-4 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 1993 Yamaha YFM350ER MOTO-4 ATV.
Shop Axles for a 1993 Yamaha YFM350ER MOTO-4 ATV.
Shop Lubricants & Solvents for a 1993 Yamaha YFM350ER MOTO-4 ATV.
Shop Wheel Bearings for a 1993 Yamaha YFM350ER MOTO-4 ATV.
Shop Skid Plates for a 1993 Yamaha YFM350ER MOTO-4 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.
