It is basic physics. Wheel hop can't be
caused by up and down motion because it starts when you try to spin the tires.
When you try to spin the tires they are trying to move forward and since they are attached to the car, the car moves forward.
But excess travel allowed in the suspension and the subassembly in a forward and back direction coupled by rubber bushing components creates a spring effect. The rubber is compressed, the wheel moves slightly forward, traction is lost, the rubber bounces back, throwing the wheel backwards as it slips. The tire then bites and moves forward again.
What happens is an eliptical type motion where an arc is caused between the time you gain traction and then loose traction. This is because the tire is also rubber.
Air bags help to dampen this movement, but to truly solve it you need to tighten up the suspension and the assembly that the suspension bolts to.
Many people have just tightened up the suspension and not found it would eliminate the problem. MannySC, the guy who built a inverted SC and air to water intercooler, messed with his car and changed how the assembly that mounts the suspension is mounted to the body of the car. He removed or reinforced the mounts with steel plates and eliminated the wheel hop.
He hangs around mostly at
www.tbscec.com.
An excellent discussion of this issue can be found by clicking below to be brought to the thread at their website:
Wheel Hop TBSCEC Thread