When I got the swing arm back from powder coating, I install the drive shaft and the new swing arm bearings.
Parts
I purchased the following parts from Cycle Works.
| Part # | Description | Qty |
| 07 11 9 985 005 | SWING ARM BEARING, 1970 to 1980 AIRHEADS | 2 |
| 31 41 1 233 252 | SWING ARM SEAL – 1970 to 1980 | 2 |
Tools
You can use the aluminum plate in the Cycle Works swing arm and wheel bearing puller tool to install the outer bearing race. Or you can use a large socket and the old outer race.
Cycle Works Swing Arm Bearing Puller (Source: Cycle Works)
I used a torque wrench that goes up to 200 FT-Lbs to tighten the drive shaft coupling.
Install Drive Shaft
The drive shaft has a taper as does the coupling. These need to be squeaky clean, no oil, not even finger prints.
Close-up of Tapered End of Drive Shaft
Tapered Hole in End of Coupling
Drive Shaft Tapered End with Coupling
I used acetone and brake cleaner on the tapers and wiped with a clean blue shop towel until there was no discoloration on the towel.
I put the drive shaft fixed U-joint in the vice with rubber jaws and tighten to secure the shaft.
Clamping Drive Shaft by Solid U-Joint
Then I put the swing arm over the shaft. I found it easier to see what I was doing by rotating the jaws of the vice.
Swing Arm Over Drive Shaft
I put the end of the coupling with the taper over the taper on the drive shaft. Then I finger tightened the nut on the threads on the end of the drive shaft.
Coupling On Tapered End of Drive Shaft
Nut On Drive Shaft Inside Coupling
This nut should be tightened to 150-180 FT-Lbs which is “a bunch”. I took it up in steps, 75, 100, 125 and then 150 FT-Lbs. Here is the swing arm with the drive shaft installed.
Drive Shaft Installed in Swing Arm
Install New Swing Arm Bearings
The swing arm bearings are the same as the wheel bearings. You can use the Cycle Works aluminum plate to drive the outer seal or you can use a socket and the old outer seal.
The procedure for installing the swing arm bearings on the 1977 R100RS is the as I showed on the 1973 R75/5. You can read about that work here.
New Swing Arm Bearings
The old outer race can be used to drive the new one. And, there is a blanking plate that seals off the right side hole to keep the grease from filling the swing arm bearing tube.
Old Outer Race for Driving New Outer Race and Left Side Grease Cap
Left Side Open Across Width of Swing Arm
Left Side Grease Cap Installed
I drive the outer races into the swing arm. Then I pack the inner races with grease and install them into the outer races.
Grease in Swing Arm Bearing
Then I drive the grease seals in using a 36 mm socket and the old outer race.
Tools to Drive Dust Seal and Bearing Race
There is a “top hat” that fits inside the seal. I insert it so the rim of the hat is on the inside of the seal.
Dust Seal and Top Hat
Top Hat From Rear of Dust Seal
Top Hat From Front of Dust Seal
I freeze the seal for 30 minutes and then push it into the hole with my fingers. I use the flat face of the 36 mm socket to drive the seal evenly into the swing arm. When it about flush, I use the old race to drive the seal deeper so it is just below the edge of the hole.
Dust Seal Installed