Board index Flathead Power-Technical Questions, Answers, and Suggestions K-Models 55KH REAR SWING ARM FORK


Post Sun Oct 12, 2008 6:07 am

Posts: 121
Hi there guys,
noticed recently my rear swing arm pivot bolt was loose... now it obviously had a slotted nut and keeper on the opposite side (primary side) but here's the thing: how do you keep tension on the primary side nut whilst tightening the pivot bolt head? It would seem you would have to have the motor removed as the inner primary case is very much in the way. Not a pretty concept indeed!

Any thoughts welcomed! Best, Nick.

Post Sun Oct 12, 2008 10:44 am

Posts: 591
Location: Crewe, Great Britain

??? Nick,

The big nut with 2 holes is not for the axle!!! The axle nut has 2 flats that sit in the slot behind the primary casting, hence it's trapped in rotation so you can just tighten the shaft from the other side, that's all that's required!!!


Post Sun Oct 12, 2008 1:47 pm

Posts: 217
Location: Palo Alto, CA
Be careful in there - I had a mechanic tighten mine and chip a chunk out of the cases. Maybe vise grips or pliers might allow you to hold it while tightening the other side? I'll defer to the more experienced out there though...

Post Tue Oct 14, 2008 7:25 am

Posts: 121
thanks, it wont tighten by itself however, it wont go hard up Patrick; not feeling trapped at all? if I lever a plate against the case and inside of the 2 hole retainer it will tighten until that lever losses its grip. And putting a lever against the case at the back of the primary feels rotten: waiting for a crack in the case kind of a feeling. Am I doing something wrong? Is the 2 hole nut not tight enough against the slotted nut. It feels tight (the 2 hole ring that is) are you meant to punch the holes to tighten? Not much room in there at all for that...

Hope you're well. Best, Nick.

Post Tue Oct 14, 2008 2:34 pm

Posts: 591
Location: Crewe, Great Britain

Hi, Nick,

If I were you, I'd check if the bearings are the right way round, it's very easy to fit them backwards.

The inner "bigger" diameters should face the frame, the outer ring "smaller" diam facing outwards. The left big nut should be tightened until the inner is flush with the left inside swing arm face. Install swing arm in frame, not forgetting the dust shields, tighten axle hard, this fully pull the inners on the frame and adjust no play plus a bit from the other big nut on the right hand side, it pulls the outers on top of the inners.


Post Wed Oct 15, 2008 4:15 pm

Posts: 9
Don't tighten the bolt too tight.With the rear wheel and shocks off and the swingarm on a hanging scale ,tighten it to when you pull up on the scale it takes 7 pounds to lift the swingarm.After all it is supposed to pivot.That's how the master builder at F&S told me to do mine.

Post Wed Oct 15, 2008 4:30 pm

Posts: 591
Location: Crewe, Great Britain


The axle should be dead tight... The load on the swing arm is achieved with the outer threaded ring on the right.


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