yes it is critical. I am not saying weld some mounts on a frame and its done because that is not how its done but if you have any common sense on how the geometry works on a front suspension its not bad at all....
Originally Posted by gearhead1011
Bump steer is critical. I just fixed a car for a guy that had big block installed in place a a small block. He said the car drove great before the engine swap and was almost impossible to drive after. I could see the toe change on this car as I raised it up and there had to be at least 3 inches of toe change through the travel in the front suspension. I found where the rack mounts had been cut off to lower the rack to clear the BB pan and the so-called chassis shop that did the swap had dropped the rack 2.75 inches without doing anything else to compensate for the change. I was able to raise the rack back up 1.25" and had to lower the tie rods at the spindles another inch but I eliminated the bump steer altogether. It is possible to get lucky and get the steering geometry close enough especially if there is very little front suspension travel. If you don't have the ability to or access to someone that knows how to set it up correctly then you will be better off with a kit that has been designed for your combination. 1/8" difference in the height of the rack & pinion can make a significant difference in bump steer.