I have a sad noise when I go into 4 wheel drive, sounds like pinion gears banging but it seems to be in the driver's side front wheel hub. With both front tires off it's quiet until u push in the drive shaft on the passenger side and activate the driver's side drive shaft. I switched automatic hub cups from side to side but it's still the driver's side that makes the noise. Is there a spring or clip in the differential that is on the driver's side shaft? Or do I need new hubs?

 

there's 2 round springs that fit over a sleeve on the axle and each side only had one of these springs, plus I replaced the hubs and now all is well. I think the problem was these round springs all along, not the automatic hubs.