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Stiff R80 Final Drive

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Shortly after taking delivery of an '83 R80ST I noticed that the rear wheel did not turn freely. With the bike on the center stand and the transmission in neutral, it took considerably more effort to turn the rear wheel than other monolever bikes here. The wheel stops immediately after removing rotational force; there's no coasting to a stop.

The bike is new-to-me, so the transmission was removed to perform a spline lube. The output flange of the transmission turned smoothly with normal effort, so that wasn't the issue.

With the final drive on the bench, I'm unable to turn the input spline with my fingers, but when I gently clamp the three wheel studs in a bench vise, the housing turns smoothly, but with some effort.

Is this normal?

Should I be able to see rotation of the crown gear when I attempt to turn the input spline with my fingers?

Could an old and stiff crown gear seal be the cause?

Any suggestions for diagnosing the issue would be appreciated.

Posted : 11/20/2022 13:21
Richard W
Posts: 2552

On the single-sided road bikes, I have had to replace the large 8" radial bearing in the final drive housing. This was apparently caused by infrequent final drive oil changes. The one in question was loose (movement at the tire), but I've heard of these bearings failing in other ways. 

If you care to inspect, the drive cover pops right off and for the price of a gasket can be fully inspected. There's only the pinion and pinion bearings, the crown gear, it's 2 bearings, and 2 oil seals.

This post was modified 2 years ago by Richard W

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

Posted : 11/21/2022 08:07


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