That is what the mechanic said after tearing my rearend out of my truck AGAIN. They are haivng to replace all the bearings. Is there certain bearings you have to use with a EATON? I know my factory bearings werent right so we ordered different ones. I am lost. He said my backlash was perfect so i dont know what is up

 

Well I'm NOT an axle expert, but I do set my own Jeep gears. If I remember correctly there is a carrier bearing preload and a pinion bearing preload. The carrier bearing preload is set by adding shims between the bearing and the carrier, which you have to do equally to each side to get the desired "load" on the carrier when it's wedged inside the housing. Too much load and it becomes a PITA to get in or out of the housing without a case spreader. Too little and it can wreak havoc on diff by allowing the carrier and ring gear to move side to side. The pinion bearing preload is set via crush sleeve on the pinion, if I'm not mistaken. If you don't use a new crush sleeve on the pinion, it's almost impossible to set the proper preload.

I always use new Timken bearings and shims when I regear a diff. I don't know what would cause a diff to somehow magically loose it's preload all on its own, but then I'm no expert either. Someone else will need to jump in here. Also feel free to correct me if I'm wrong, all of my experience has been with Dana and Ford axles, not GM.

 

I believe that the stock crush sleeve acts sort of like a spring and after time after time of it absorbing the deflection of the gears it loses some of its preload on the
bearings.

 

Sounds like a bad install to me, It sounds like the bearings either werent pressed on all the way, or he didnt use a case spreader to get all the shims in there necessary to set them up right. Its pretty much impossible to get the gears setup in these rears without one.

Also the crush sleeve could be a problem as well. But it normally is not a problem unless the installer overtightens the pinion nut and then loosens it up.

You are better off not using a crush sleeve because of the reason stated above. They make it easier to install but they can cause problems. In most high performance applications, they are replaced my spacers instead of the actual crush sleeve