Originally Posted by BuGgYBaShEr.28

Sounds like the servos are not holding when under a load like that, if its the stock servos than yes that will happen. Plus they don't have the power or torque to hold those big tires. I run dual savox 0231 they are waterproof with 208oz each, making 416oz total. Stock you'll have only 250oz, so quiet a bit of difference.

As for as you turning the spur, with the motor off I would think all four wheels should go in the use direction? That's what the motor does so I dont see a problem there. Usually if a diff is in the wrong direction, the truck won't and can't possibly move at all. One will go one direction, the other I'm the opposite, making them fighting each other so it wouldnt move if that's the case. Hope I'm of some help bud.