Spinning wheels and the tires start bouncing puts alot of pressure on axles. Seen everything from a chevy, ford ,dodge, and rice burners loose a diff for that reason.

 

I had the same thing happen to me on my 01 cobra at the track, blew the *** end right out of it half way down the quarter mile, after a couple of runs on the track

 

doesn't take much once it starts to bounce it jerks the guts out of them

 

That kinda ruins the trip! I destroyed my internal front diff and it was covered under warranty. It came out as metal scraps all over the floor and still drove fine! As far as the outer case? I would imagine they would not cover it. Most dealers are pretty strict about warranty rules. My dealer is GREAT about off road damage. I have heard about them cracking like your situation but I haven't heard of the outcome on them personally in regards to manufacturer defect. My dealer covered one like that which was driver error and they put it under warranty. Sounds like your original dealer should move to a different car line and stay away from hummers.

 

It depends on the warranty, if it's a factory warranty Hummer should cover up to moderate off road damage as long as it's not considered "Abuse".

Ie. Lo gear and slow over rough terrain.

If it's an aftermarket warranty, good luck, those guys will say anything to get you to sign up, until they start seeing large repair bills for a big 4x4 then they'll either cancel the policy with a refund or say it's not covered.

Old school Hummer dealers will know that owners will take these trucks off road and busted transfer cases, half shafts, etc are.. relatively normal. Other dealers will flip out at someone actually taking a work truck or 4x4 suv off road, so your mileage will vary.

Typically speaking, Hummers aren't built for high speed off roading, most vehicles aren't without very heavy modification to suspension. I've seen Hummers [h1/h2/h3] modified for high speed desert racing, all of them use custom fabricated or modified control arms, upgraded tie rods, and high end bypass shocks with coolers. That's the way to go if you need speed over rough terrain.