Outer Limits 4x4 Board

Something keeps shattering my front Right Wheel Bearing..When I replace the bearing all is good until I'm offroad and lock in the hubs...I get a grinding noise at the front still and then if I push too hard for too long..eventually after 3 - 4 trips out somewhere doing this the wheel bearing will go again. I've taken it to the mechanic to get him to look at it and he says there is nothing wrong and have spent over $1600 trying to get it fixed again and again. I just want it fixed..Any Suggestions?

Cheers,
Kurt.

these r ifs in the front yeah? u probably have got a bent cv or stub, but if it was ur stub you would notice it, pull it out ur self take it to a machine shop or sumone with a lathe and check the axle for run out, other than that i dont no.