How did you center the box is what I should have asked...
It should be turn the wheel all the way to lock in one direction, then all the way to lock in the other direction while counting turns. Divide total turns by 2, rotate the steering that amount and the box is centered. I seem to remember 4 1/2 turns lock to lock.
Eyeing it up "90" to the frame is too vague, you could be off by 3/4 of a turn from center.
Rene