Are the washers that come with the aftermarket Independent bushings different than what the trucks ship with?
I was setting up my dad's board (Indy 159 standards - stage 11) and the bushings kept slipping out of their washers, leaving the trucks heeled over to one side. We tried a set of 94a and 90a and both had this slipping.
We've been trying a few different bushing duros and the washers have changed around. I eventually found the set of washers the truck originally came with and they had a deeper cup to the washer than what the aftermarket kit came with.
Here's an after when we swapped in the new bushings and the OG washers:
After swapping, the board rode normally and had good return to center. The bushings in the kit would not return to center since they slipped out of the washer. This sounds like a crazy conspiracy and I've been comparing the other Indy sets I have around. It seems like the original washers from my stage 10 139s are also a little thicker and have more cup to them. There seems to be a loose factory tolerance overall though and some sets are thinner, less cupping than others.