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racers narrowed the front fork on their machines. Probably to lighten them
as well as stiffen them up. I have some people tell me they where
primarily used on the mile tracks. Anyhow enough talk.
Cut the forks apart on the inside of the leg. Grind the weld off and drive out the left over cross shaft pieces, this leaves a person with the original hole Indian used. The original cross shaft material had a 7/8"o.d with a 9/16" i.d. On my racer fork thin wall chromemolly was used instead. If you want to reuse the original cross shaft material the top piece can be reused and possibly the bottom also if the fork is narrowed enough. If you can't reuse the lower piece then the tack welds must be ground off the spring perch and then sweated off. I like to use nickel silver rod to braze things back together as it is a lot stronger than regular brazing rod.
On my fork I narrowed them to 6 3/8' wide so that I can use a BSA front hub for road racing. The original forks where narrowed to 6." After everything is taken apart I load up everything in the fork jig and figure lengths for the cross braces as needed. I cut blocks of wood to place between the legs to keep them straight. After everything is all fitted up the spring perch is tacked, brazed to the new cross shaft and the whole assembly tack welded in the jig. It is then removed from the jig and finish welded.
After the fork is narrowed it can be used for measurements to narrow the fork T assembly as well as the fork crown. I used the mill and lathe respectively to do this. Hope this info helps somebody out. If needed please ask questions.
PS: I built the jig for three cross shaft pieces so that bent forks could be
More on Jim's Sport Scout racers here:
Part One: 1936 45" + Big Base Scout Racers
Part Two: All about Factory Racing Tanks
Part Three: How to stiffen up your rear frame for racing
And of course Project Big Base Cases!
Narrowed forks on one of
Jim's racing Scouts
Narowed and stock forks