Reply to "Heavy Uprights"

Halls rear uprights are (or were at one time) made of 7075 aluminum, but no mention is made by anyone making alloy suspension parts of heat treating after machining. Cutting, sawing etc heats and changes billet aluminium, and in the Aeerospace game, we assumed that ALL machined parts both steel and aluminum reverted to T-zero strength (that is, fully annealed) regardless of what heat treat level you started with. Proper heat treating of aluminum parts can easily double the costs of machining them. 7075 t-6 would be an excellent material to use as its about the same tensile etc as mild steel, but t-zero is weaker. 7075 is also unweldable so a mistake in machining is not repairable.Some hobbyists like me have machining capabilities, but proper heat treating (and testing to verify your results) of aftermarket parts is very rare. I know of one owner that adapted Halibrand cast aluminum racing uprights, but that adaption was a chore since the rear upright was intended to be used with a Corvette type suspension (no upper ball joint). I also remember seeing one racer at a 'Vegas open track on the trailer early. The lightweight a-arms the owner built, bent during an off-track excursion. Not a crash, just ran off the track into the dirt, and that was enough to overstress the front suspension. Testing is important, too....