Finally got rid of the rear wheel steering after two years on my 2017 M8 Glide.Had it to the Shop and Suspension specialists a few times and followed many threads on the wobble.Thanks to Stonecold and all the guys on my last thread,I just got into it and pulled the whole works and swing arm apart.
Found 3/16"play across the swing arm.The swing arm Spherical bearings were rattling on the undersized arm shaft.Bearings were like new.No guarantee a new shaft would be any different so I silver braized the original and skimmed it back to spec.Added a 1/8 stainless washer on each side,wedged between the swing arm and the isolators. Locked it all together. Oh Boy what a difference! Handles like a dream.Zero deviation at scary corner speeds! Even low speed manuvering is awesome.
Happy camper now!

 

Do you care to post few pictures to help better understand what was modified?

 

Sorry,the work is already done.The swing arm axle connects the swing arm through two spherical, self aligning bearings in back of the transmission housing.The wobble issue came with the new M 8 from the factory.
Somehow the shaft was machined way too thin.There was play between the shaft and the inner bearing housing!
Self aligning bearings can rotate off line so they have to be tight fit for the shaft to keep them dailed in.
There are many reasons and cures for wobbles. For me this was an unexpected last stop option but proof that it can happen.
When I bought this bike it rode like a Rigid frame.Pulled the Rebound shock and counted 3 extra spring coils.
Quirky but no "hard" feelings! Love all Harley's

 

Are you the first to do this or did you get the idea from others that are doing this preventative cure?

 

If nothing else, this experience proves that the swingarm can surely be a source of wobbly handling. Riders usually look at the front end, and stay there, never proceeding to the rear end of the bike.

It certainly is concerning, that a swingarm could come out of the factory in such out-of-spec condition. This is a clear safety issue. Heads should roll.