Bent Swingarm - Simple Fix

marshg246 · Feb 17, 2021

I realized today while trying to install the rear wheel on a 74 850 that the swingarm was bent. I spent a lot of time checking and determined that the only thing wrong was that the flat plate on the drive side rear was bent inward about 3/8". This was making it very hard to get the wheel and spacers in, was causing the sprockets to be out of alignment, and was forcing the wheel to be crooked. Sorry, I didn't take pictures of the problem but to fix, I put an old axle through from the outside and rested the nut portion towards the front of the slot. Then with an old fork tube over the axle, held onto the rear of the bike and pushed on the fork tube with my side. First push almost fixed it and the second made it perfect! You would think that thick metal would be very hard to bend - it's not - it's quite malleable and it's back to straight.

My guess is that the swing are was dropped at some point as the timing side was not bent.

batrider · Feb 17, 2021

Old fork tubes are so useful!

850commando · Feb 17, 2021

Along enough lever...

BERT · Feb 17, 2021

marshg246 said:
I realized today while trying to install the rear wheel on a 74 850 that the swingarm was bent. I spent a lot of time checking and determined that the only thing wrong was that the flat plate on the drive side rear was bent inward about 3/8". This was making it very hard to get the wheel and spacers in, was causing the sprockets to be out of alignment, and was forcing the wheel to be crooked. Sorry, I didn't take pictures of the problem but to fix, I put an old axle through from the outside and rested the nut portion towards the front of the slot. Then with an old fork tube over the axle, held onto the rear of the bike and pushed on the fork tube with my side. First push almost fixed it and the second made it perfect! You would think that thick metal would be very hard to bend - it's not - it's quite malleable and it's back to straight.

My guess is that the swing are was dropped at some point as the timing side was not bent.

View attachment 21884

BERT · Feb 17, 2021

Norton special tool#10 ...

Torontonian · Feb 18, 2021

Yes an old fork tube should be in every tool box. Learned that trick many years back . Glad you straightened it back to level runnings so easily. Relief.

Stephen Hill · Feb 22, 2021

Old fork tubes are also useful as rollers for moving heavy objects, like lathes and milling machines. I keep a half dozen around for that purpose. You need lots cause they roll at a different speed than the item you are moving, so you feed new ones in front as they spit out at the back.

Bent Swingarm - Simple Fix

marshg246

batrider

850commando

BERT

BERT

Torontonian

Stephen Hill

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