That is a really good question. Replying here from Wolf Point, Montana... enroute to CCR.
Honestly, I don't know when or if axial play shows up during an impending fnal drive failure. I suspect that roughness during wheel rotation is a more likey early indicator. But, in some of the failed bearings I have inspected, there is a wallowing out of the bearing races which would allow for some lateral play resulting in a "wiggle" in the wheel. Whether or not this actually can be detected is speculative on my part. All of the failed bearing I have seen have severe spalling of the balls which would result in a roughness that could be felt during wheel rotation. This is why I suggest getting the brake pads out of the way of the rotor to allow for sensing of wheel rotation smoothness.
Based on the reports of those who have had drive failures, there are very few indications of impending failure. I think you'd have to be checking very frequently to detect a failure before it occurs.
You referred to "spot welds" on the retainer. I haven't seen any bearing with a welded retainer, they all have had rivets. The failed bearings I have seen have had retainers that were broken with pieces of retainer "floating" in the lube or at the drain plug magnet.
There have been lots of posts about efforts to detect impending crown wheel bearing failure. I doubt that detecting impending failure is going to be fruitful. The suggestions regarding detection mechanisms using drive temp or metal particles in the oil are interesting but I suspect are likely to result in false postives to the point of distraction.
Preemptive rebuilding of the final drive or being prepared for failure are the approaches that make the most sense to me. Not what most folks want to hear I suppose, but that's my take on it.
Originally Posted by Dick
Hey, Curtis - question for ya, since you've rebuilt a gazillion final drive hiccups.
When ole Toad spit out two final drive bearings (~60K and 110K), I never felt any play/wobble using the 3 and 9 shake-it routine. I did have the click-a-click-a-click sound while rotating the wheel on the 60K failure, and the grinding sound on the 110K failure. In both cases, the ball bearing retainer/keeper strips had broken at one or more spot weld places, and let a couple of the bearing/s have free roll in the race. Soooo - my question is, what happens that allows the wheel rim to have some wiggle play?
That's it - just tryin' to git my head around the scenario that goes on before the seal is fractured and lets the oil out!! Thanks in advance, Curtis. And best regards on your final drive rebuild gig at CCR. Hope you git it video'd for archival reference. Safe trip out there and back, Curtis - enjoy the camaraderie and the 'vacation'!!!