I wouldn't recommend using allthread it is pretty soft and would probably bend.
I may be wrong on this but I don't think allthread is even Grade 5 which is what standard bolts are.
ya i tested some all thread and it was very flexable but i did find a 3/4" yard trailer axle that ill need to extend about 6 inches hopefully northern will have some bearing stuff. ill probably post some build pics once i get some money for parts. man i wish i didnt sell my old kart