February 28, 2007
Yeah, yeah - we've all had that conversation. I was just suprised that you didn't stick with the 'jack my wife bought me' version of it.
Now, back to your original question. On an SN-95 ('94-'04) Mustang, the main reason you need to possibly play with alignment after lowing is this:
Before lowering, the ball joint ends of the lower control arms are lower than the inboard ends of those arms. After lowering, they're closer to level (may be above or below the inboard ends depending how low you went). This means that the balljoint to balljoint distance is longer. This has two effects on your alignment:
(1) Since the tops of the struts didn't move, and the bottoms of the struts DID move (outward, along with the balljoints), the static camber has changed, and become more negative. At a 2" drop causes a stock "before" alignment to become about -2 degrees camber (which is a lot). Or more.
(2) Since the steering arms (tie rods) DIDN'T get longer, but the balljoints moved farther from the center of the car, and the steering pivot at the balljoint is forward from the steering arm, the result is that the wheels will now be more toe out than they were before you lowered the car. A 2" drop will result in actual toe-out alignment on the cars I am describing. This causes very 'darty' steering.
Both of these changes make the car feel more responsive to steering inputs. Both of these changes also increase tire wear dramatically. A simple alignment can fix both of them easily.
I don't know enough about an '05 front suspension to know how this information applies. Hopefully I gave enough information so that you can figure it out on your car.