Rear Travel Arch

Just curious, when the rear wheel (one tire only) up travels does it go straight up and down or does it have some other arch to it? What about the front? Search and came up with nothing.

It goes up, tilts inward, and moves inward. It also gets pushed backward because of the angle of the spring.

A four wheels move up and down in a arch. Hold a pencil in the middle, wiggle it so the ends go up and down.. See the arch, same thing happens, basically.

On a typical XJ leaf spring, the leaves have a downward curve to them. As they get compressed, the curve gets flattened out and therefore the leaves elongate. Since the front of your leaf springs are attached to a fixed pivot point, the extra length gets pushed toward the movable pivot point (shackle) at the rear of the leaves. Your axle (and therefore your wheel) get pushed back toward the rear of your wheel well along with it.

On some other vehicles with flat leaf springs the opposite would happen. They would try to curve upward when compressed which would cause the leaf to shorten. This would in turn cause your wheel to move toward the front of the wheel well as the spring is compressed.

As winkosmosis mentioned, there is also some movement on the left to right axis when only one wheel moves up. The middle of the axle would be the pivot point in this case and the wheels will tilt in and out in direct relation to the angle of the axle.