Myth:
The drive shaft's splined connection at the final drive is lubricated by gear oil.
Fact:
The splined connections at both ends of the drive shaft are lubricated with lithium soap based grease or equivalent. Many have used the Honda Moly 60 Paste with good results. Moly offers the lowest friction and best protection of all commercially available lubricants. Moly is a solid lubricant which can withstand extreme pressures, and temperatures up to 1500 DegF. The universal joint splines and drive shaft splines can all be lubricated with these greases.
Leakage of the final drive gear oil is controlled with three oil seals and two O-rings. The oil seal and O-ring controlling leakage around the final drive's pinion gear are located so that no oil should reach the splined gear coupling which interfaces with the drive shaft. The drive shaft is splined to the coupling and that greased interface is protected from dirt and moisture contamination by a flexible dust seal mounted on the drive shaft. This seal fills the circular area between the drive shaft and gear coupling.
See the “Shaft Drive” portion of the “Chassis” section of the Yamaha Service Manual.
Myth:
The forward end of the drive shaft moves within the universal joint.
Fact:
A compression spring is located at the final drive end of the drive shaft. This spring pushes the drive shaft forward toward the universal joint. If any front/back movement occurs along the drive shaft it occurs at the final drive end. Thus, the lubrication of the shaft's splined connection at the final drive is the most critical. Grease at the universal joint's splined connections is desirable for two reasons: inhibit rust formation on the splines and ensure that the splined connections don't become frozen and difficult/impossible to disconnect.
The drive shaft's rear splined connection has a large diameter and surface area. The torsional forces are spread over a large splined connection. Since this interface has the potential for movement lubrication is more critical here. Movement in this interface (if any) should be minimal. The center of the universal joint and the swingarm's pivot point appear to be in good alignment. So, the distance from the universal joint to the final drive probably doesn't vary as the swingarm moves up and down. A flexible dust seal on the drive shaft keeps dirt and moisture out of this critical splined connection.
The drive shaft's splined connection at the final drive is lubricated by gear oil.
Fact:
The splined connections at both ends of the drive shaft are lubricated with lithium soap based grease or equivalent. Many have used the Honda Moly 60 Paste with good results. Moly offers the lowest friction and best protection of all commercially available lubricants. Moly is a solid lubricant which can withstand extreme pressures, and temperatures up to 1500 DegF. The universal joint splines and drive shaft splines can all be lubricated with these greases.
Leakage of the final drive gear oil is controlled with three oil seals and two O-rings. The oil seal and O-ring controlling leakage around the final drive's pinion gear are located so that no oil should reach the splined gear coupling which interfaces with the drive shaft. The drive shaft is splined to the coupling and that greased interface is protected from dirt and moisture contamination by a flexible dust seal mounted on the drive shaft. This seal fills the circular area between the drive shaft and gear coupling.
See the “Shaft Drive” portion of the “Chassis” section of the Yamaha Service Manual.
Myth:
The forward end of the drive shaft moves within the universal joint.
Fact:
A compression spring is located at the final drive end of the drive shaft. This spring pushes the drive shaft forward toward the universal joint. If any front/back movement occurs along the drive shaft it occurs at the final drive end. Thus, the lubrication of the shaft's splined connection at the final drive is the most critical. Grease at the universal joint's splined connections is desirable for two reasons: inhibit rust formation on the splines and ensure that the splined connections don't become frozen and difficult/impossible to disconnect.
The drive shaft's rear splined connection has a large diameter and surface area. The torsional forces are spread over a large splined connection. Since this interface has the potential for movement lubrication is more critical here. Movement in this interface (if any) should be minimal. The center of the universal joint and the swingarm's pivot point appear to be in good alignment. So, the distance from the universal joint to the final drive probably doesn't vary as the swingarm moves up and down. A flexible dust seal on the drive shaft keeps dirt and moisture out of this critical splined connection.
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