Grand Prix 125
Main Motorcycle: 1969 Daytona T100T
Join Date: Sep 2018
Location: West Sussex UK
I think the problem may be that you have been sent later part 82-7706 instead as TriCor Andy apparently has both 82-4284 and 82-7706 part numbers available. Why not contact him and query the order? You need the one he describes as "Brake pedal pivot CEI" (i.e. with a CEI thread) which should have the longer spindle thread to go through the frame lug.
Just for information, after 1966 the rear frame was redesigned and strengthened and with a different mounting method for the swinging arm spindle using side plates welded on the frame tube. It's on the left hand side plate that the spindle is bolted through instead of the lug yours has. It uses the different part number 82-7706 as this only has to go through the side plate thickness (about 1/4") and thus only needs a shorter thread (note: also changed to UNF thread).
You don't show your location, but part 82-4284 does seem to be available from some suppliers such as Baxter Cycle in the US.
Hope that helps!
Previous bikes: '58 Tiger Cub; '61 Bonnie; '67 Bonnie; '69 Bonnie '70 BSA Lightning; '71 OIF Bonnie; Honda 500-4
Last edited by BrianG; 08-22-2019 at 01:17 PM.