Team O’Neill and why 4wd braking is better is snow and ice. More after the jump.
Their reasoning is due to a transfer case locking the front and rear wheel speeds together. Since the front and rears axles are now locked together, the front tires can’t lock up unless the back tires do as well.
Essentially the front brakes don’t work as effectively due to higher driveline forces (due to the front and rear being locked). The front brakes now have to deal with the force of the engine.
This reduced braking force translates into a reduction in angular acceleration(deceleration if you prefer, which is still an acceleration just in the opposite direction) at the front wheels. The reduced angular acceleration is the result to less torque applied to the wheels - higher velocities on the disc reduce the coefficient of friction, ie. less force for a given brake system pressure. This applied torque is lower than the torque applied form the surface onto the road. Hence the wheels don’t lock up. Locked up wheels extend braking distances on snow and ice.
My explanation is terrible but that is the concept.
I’ll try less words. Since the front wheels are now locked in to the engine and rear axle the front brakes aren’t as effective. This is a benefit on snow/ice since they aren’t strong enough anymore to lock the tires at high speeds.