I have gained a lot of experience with U joints on machinery over the years and have a pet theory regarding greasing .
They never wear out evenly ,usually one side or sometimes both sides of the "spider" will fail before the other , but never all 4 together .
The cups contain roller brearings ,which by their nature ,require very little lubrication , so why does one side fail before the others ?
Very often there will be rust present .

Also Sjeord comments upon the short life expectancy of the replacement units .

I think that it has more to do with the integrity of the grease seal on the bearing cup .When the rubber seal begins to fail it allows moisture to be drawn into the u joint .[It may only be a very small amount of moist air being sucked into a warm u joint as it cools down after a long ride ] But over a period of time there is sufficient water to degrade the grease in the cup and the bearing fails.
Seals can fail through old age and the effects of ozone and UV light .

The out of phase condition I personally believe is due to the u joint failure and not vice versa .

Consequently I would always grease the u joints sparingly at a regular interval [based on the useage of the bike] and always before storing the bike for any length of time .In order to do this a grease nipple is necessary ,which would require a modification .This mod impressed me :


I believe this type of mod ,other than the urethane damper , could be done by a competent machine shop anywhere if you had the correct parts to hand .
If I was going RTW ,I would have my driveshaft modified in this way and lubed with synthetic grease .


Best of luck .
Dodger

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