Monday, January 13, 2014

Inspecting and Fixing the Frame

The first thing I noticed with the frame was that it had no side stand or lug. It still had a center stand but it was bent. I bought a replacement lug on eBay and then modified its contour to match the one on my 1970 Lightning. It’s nice to have a bike for comparison when parts are mangled or missing. Although the Hornet had most of its pieces, it had been reworked and I was not sure what was original and what was not.

I purchased a side stand off of eBay and then tac welded the lug onto the frame in a position that matched the Lightning's orientation. This was done before my “rough assembly”.  After the frame was broken down to its components I TIG welded it permanently into place.

New lug tack welded into position. 

Reconfigured on a mill to match the original lug. 

Fully welded into place and blended to the frame with air grinders. 

I made several BSA frame tools based on prints in my BSA workshop manual. The backbone gauge highlighted a slight bend in the frame. It was not enough to be an issue or require repair. Frame bushings were machined to mount the frame on a surface plate for inspecting dimensions to the factory prints. Overall everything looked good, and aside from adding the side stand lug and fixing bent brackets, it was ready to go. 

Checking the steering head angle on a granite surface plate. 

Inspecting side to side dimensions with a height gauge. 

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