[TypeZer0]

i'll try to explain. lets assume that the tires have perfect traction so there's no wheelspin. with the regular diff (gear type) power is instantly transfered to the wheels thus accelerating away with full power. the ball diff on the other hand, kind of acts as a slipper clutch. if you've looked inside the ball diff (i can post pics of both ball diff and gear diff both taken apart if requested) two metal rings connected to the driveshafts press against 5 ball bearings in the middle. metal to metal isn't the best material for surfaces that need to grip. thus, when full throttle is applied, the ball bearings, which are carried in the middle on the main housing, will be overcome with too much torque and slip on the two metal rings. with the tires fictional perfect traction, no power is transferred. higher quality ball diffs will allow some adjustability to loosen and tighten it. this will make turning easier/harder and tightening it will give the ball bearings a higher threshold before it slips.

basically, the xmod ball diff will limit the two wheels connected to it from spinning at too different of a speed making it harder to turn. it tries to turn both wheels at the same speed so that if one wheel loses traction, the other still has power to keep it moving.

this is opposite of the gear diff where it's great at turning but when one wheel slips, power is lost to the spinning wheel