Long term swingarm needle bearings report

Finally. Back in 2004 when I rebuilt the bike (to bare frame, motor, GB, every single thing to smallest part, etc) I installed "needle" bearings inside the rear swingarm; "my thinking" they would be better. (as read and "advised" from other Norton "experts.") At the 2020 "Nortona" meeting, "Windy" noticed my kickstarter going horizontal (thanks Windy!) --- during first gear engage from dead stop. Oh no ... thank GOD I made it home ok, cause I was paranoid for sure. Time to install my rebuilt 850 motor, rebuilt GB (by https://classicbikeexperience.com/) install new iso mounts, check swingarm, etc, etc. . So much has to be removed to change a complete GB, I figured "in for a penny, in for a pound." What a huge PITA ...

Anyway, the bike has about 5K miles since my "resto" in 2004; when the needle bearings were installed. (Out of my own laziness and neglect, I never lubed them since then) As shown, both still had plenty of GREASE and oil; and yes I used grease) The drive side had no wear evident on the needle bearing or spindle. However, the timing side needle bearings are worn, as well as the spindle. Would have made more sense to me if it was the drive side --- not the TIMING side. The both iso mounts show very little wear;and all esle looked good ... to me. What really sucks is this 750 motor setup was such a sweet runner; giving 60 MPG on the round trip from Yulee, FL to Nortona; and back roads back home. (250 plus miles) ... could it be the "windjammer fairing???"

Thoughts and opinions invited and welcomed.

P.S. the bolt showing in one pic is a long bolt with washer I used to remove both needle bearings. I then installed original type bronze bearings, after soaking in oil for a week)

I went through the same thing years ago. The spindle is not hard enough to support needle bearings.
If you look at the specs for the needle bearings they say the inner race needs to be 62 Rockwell or higher. The original spindle is not even close.
The only common material that would be suitable for a spindle with needle bearings would be hardened 300M.
Or install inner races on a soft shaft.

It seems to me - despite the use for that purpose - that needle bearings are not in their proper environment in a swing arm. They are for rotating assemblies. With a swingarm, it appears to me that they would cause much more wear than a bushing because of the load and the nature of the bearing means the wear is more concentrated. IOW, there is less surface supporting the load at any given instant then there would be with a bushing. The swing arm doesn't rotate, so the needles don't either - they just work back and forth in the same spot over and over. I don't get it...

There are lots of bikes that use a roller element bearing -ball or needle -for a swingarm and they work fine, but most use an inner race, not a roller running on a semi-hard shaft.

On a Norton spindle your best off with the bushing -if you want long life.

MexicoMike said:

It seems to me - despite the use for that purpose - that needle bearings are not in their proper environment in a swing arm. They are for rotating assemblies. With a swingarm, it appears to me that they would cause much more wear than a bushing because of the load and the nature of the bearing means the wear is more concentrated. IOW, there is less surface supporting the load at any given instant then there would be with a bushing. The swing arm doesn't rotate, so the needles don't either - they just work back and forth in the same spot over and over. I don't get it...

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I felt the same way about BMW airhead rocker arm bearings. IMHO bushings were better for the limited rotation they went through.

I sure appreciate the comments and expert advise, as that is why I asked. Makes sense to me now, what with the Norton spindle shaft NOT being hard enough. My KZ1000s and several of my other bikes have needle bearing swingarms; so I thought at the time I would try it. Perhaps the KZ1000, and other bikes spindles --- may be MUCH harder then the Norton "softie" one. Attached are last ride and at job start, much easier with the "cheery picker" boxes, jacks and boards. How does everyone else do this ??? I forgot what a PITA it was ...

nortriubuell said:

... How does everyone else do this ??? I forgot what a PITA it was ...

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i have an assembly table but no way to lift, so i strip of the real heavy stuff, including wheels etc and then manpower it onto the table . your lift would be nice to have. i've been contemplating a lifting table, i also want to get a lift when working on the cars, and the garage is not big enough for all, guess i'll be thankful that i still am flexible enough to manage without... and it was -25c this morning

Last time I replaced a spindle I lubed it with lightweight shockprook gearbox oil because I had some extra. I like the way it really clings to metal parts. Do not know about long term use.