My friend bought a budget, Chinese built ATV quad. It has two wheel drive. The front wheels have pairs of ball bearings. After only a couple of hours of operation 3 of the 4 front wheel bearings failed big time. I came up with two guesses as to why the bearings failed so quickly. 1. The wheel bearings have a spacer between the inner races of the inner and outer wheel bearings. If the spacer does not match the spacing of the bearings when they are installed in the hub and axle shaft nut is tightened then the bearing will under go forces they were not intended for? 2. Ball bearings should have never been used and tapered roller bearings should have been used instead? Any ideas if guess 1 or 2 is likely? Thanks for any help!