The effect that you notice, when the suspension has a bump steer problem, is mainly in a fast tight corner. As you come in to the cornor, you apply the right amount of steering input, and as the car starts to compress the outside suspension the wheel will turn in tighter. So you unwind the steering a bit to keep the line, this then unloads the suspension and the car starts to head for the outside of the corner.
Cornering becomes a matter of adjusting the steering input, all the way through the corner. Instead of just holding the right line, from start to finish.
Depending on if the tie-rod is above or below the parallel, and behind or in front of the strut, it will either increase/decrease the steering input. In our case, if the ball joint is lowered, it will steer in tighter.
This is something that took Japan a long time to appreciate. Some of the worst offenders were the sports models, that displayed server steer in. Some were fixed by lowering the rack, others needed the steering arm to be reset.
Harvey.
