Project Knucklehead Frame Repair 

Knucklehead Frame
The 1946 Knucklehead Frame after it was put in the Jig and repairs are about to begin. Notice the sidecar loops have been cut out of the front down tubes and the tool box mount is missing.

It’s been awhile since any sizable progress has been made on Project Knucklehead. However, this week I was fortunate enough to be able to truck the frame to Paper Street Customs for some much needed attention. As was the case with many of these bikes, the sidecar loops and tool box mount had long been cut off. On top of this, at one point the left frame rail was cracked and instead of cutting out and replacing the damaged section, a piece of larger tubing was clamped over the damage and welded in place. The result was a poor, unstable repair and the loss of one of the floorboard mounts.

The “bulge” in the frame rail seen here is actually a piece of pipe welded over a crack in the originally frame rail

Ryan, with Paper Street Customs, made quick work of cutting out the “bandaged” frame rail and fitting in a new section of frame. He used solid slugs to add strength to the repaired section and insure good weld penetration.

The damaged section of the frame rail has been cut out and the repair piece and mounting slugs are ready to be installed.


The tool box mount on the rear of the frame looked reasonably smooth, however, the sidecar loop mounts were not. It looked like someone had used a rough cut saw to cut them off. I was able to round up some factory style castings with slugs cast in them to give the frame support and provide a solid repair.

After much forethought, Ryan mounted the frame in his custom jig designed specifically for these frames and went about cutting the sidecar loop portion of the down tubes out of the frame. Keeping the frame tight in the jig he was able to spread the down tubes out far enough to slide the new castings in place and weld them in the proper position.

1946 Harley Frame
In this “after” shot you can see the new sidecar loops and frame rail repair.


I’m choosing to leave the toolbox off of this bike so that section of the frame was not replaced. The repairs made look amazing and I’m now confident when I ride this 71 year old bike it’s not going to crack in half! At the end of the day the frame was back in my truck and headed for home. Stay tuned to see the finished motor and progress on the mock up!

To read more about the Knucklehead project click below:

Part 1

Part 2

Part 3


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