I am hearing a loud intermittent vibrating noise from the front axle, it shakes the whole truck and sounds like something rubbing on the axle. I took apart and greased the auto locking hubs, also I jacked the front of the truck up, with the hubs set to automatic and the truck running, I engaged and disengaged the 4wd using the switch in the cab of the truck, the hubs locked and unlocked, I verified this by spinning the wheels one at a time and the axle and driveshaft stopped moving when I switched 4wd off, and moved when switched 4wd on, the 4x4 light illuminates. I tied a piece of fishing line to the axle and driveshaft and went for a drive with hubs in auto position, and switch in 2wd, the line was broke when I returned. I test drove the truck again in 2wd with the hubs moved to lock position, it does not make the noise at all with the hubs locked in. My question is what is my next step, are one of the hubs bad, or is it the wheel bearing? Also when jacked up I grabbed tire at 12 and 6 and 9 and 3 oclock positions and there was no wheel play at all, but then again everything on this truck is built like a tank, but I could not feel any play pulling out on the wheel either, thank you for your help, I am unsure of my next step, all these parts are very expensive and I just do not want to start throwing parts at it, please advise, thanks again....Jon...

 

Thanks to Krewat 10-26-2008, 07:37 PM for the great advice on this forum!

"The vibration/grinding when you hit a bump is the classic sign of bad needle bearings - the front axles ride on a needle bearing inside the wheel bearing. They get dry and cause this exact problem. Fix it quick, or the axle stubs will get ruined (if they aren't already). The needle bearings in the hub don't have a differential rotation against the stub axle in 4wd, they do in 2wd. That would pretty much confirm to me the bearings need changing." Krewat

I found and replaced bad needle bearings, problem fixed for under 50 dollars! Thanks again Krewat!!!! JAR1972