what causes wheel hop?

Can anyone explain to me what causes wheel hop? I've got a 302-5 speed with an 8.8 rear with 3.73 gears and 31x10.5x15 tires. When I back-up, I get wheel hop until the clutch is fully engaged and I'm moving at more than a crawl. Backing out of the garage is a pain in the @#s because it is slightly uphill. I plan on putting traction bars on, but not sure if this will be the best solutuon. I also plan on changing the gears to a more hiway friendly set, but am afraid this will compound my problem. Any suggestions?

When going forward you are loading the spring in a way that puts lift to the front spring eye and body transferring weight to the rear ( although minor usually on our rigs). putting it in reverse you are doing the opposite and lifting the rear compounding the lack of weight to start with. Slap bars wouldn't be effective going backwards. Possibly Ladder bars that eliminate any axle housing twist and spring wrap? Other option is to always go forward.

That is pretty much what I was thinking was happening. I am planning on making ladder racks. Hope that will fix it for me. As for always going forward.....It would be hard to get her out of the garage.

JMO.. I always thought Wheel Hop occurred during a Burn Out or Spinning the tires if it is happening when letting the clutch out Normally it may be the Clutch Disk or Pressure Plate that is Bad.....My 1975 Chevy Van used to be a 3 Speed on the Column and when I would take off and let the clutch out it would chatter (Shake The Rear End)  and was even worse in Reverse... replacing the Clutch Disk ,Pressure Plate, and Throw Out Bearing, Solved the Problem.!!!... ..I may be Wrong in your Situation it just sounds like a issue I was having..

My clutch is brand new. It is wheel hop, and I think the ladder racks will solve the problem. I know I am experiencing axle wrap (spring flexing) and just wanted to see if anyone had other ideas about my problem. I know wheel hop happens during a burn out, and mine is more subtle. The wheels aren't actually hopping off the ground, they are just jerking the truck and leaving tiny skid marks on the floor of the garage.

Does this hop occur when the tires are spinning as in pealing out or spinning the rear tire
or does this happen when you are letting the clutch out to just get the van rolling?

After reading your posts again I would say you have a defective clutch or need your
Flywheel turned, traction bars and ladder bars are not going to cure your problem.

Sounds like the clutch is grabbing,,,,,,,some stuff that cause it......worn trans and motor mounts ,,,,oil from the rear main or trans ,,,,,,,bent clutch disk from hanging the trans in it .......clutch disk in backwards,,,,,clutch linkage worn out or loose,,,,,,clutch fork pivot ball loose,,,,,driveshaft yoke whipping around,,,, maybe have  someone look under there while you  hold the brakes on or  the parking brake, and try to back up and they might see what is jumping under there,,,,,,,,they are looking at the clutch fork coming out of the bell housing see if there is jerky movement from the fork, or the bellhousing, which is the engine/trans/mounts or the linkage going to the fork....or put the rear on jackstands or a lift and see where the jerking is coming from.