Nice thread
@OwnerCS.
IMHO. Some radial play between FDS and diff side tube, is normal!
I just checked for radial play, between FDS and DS diff tube. In one I just installed a new OEM FDS on a 250K 02LX. It has some radial play, which seems normal to me.
Setting snap ring gap, after driving to settle grease with tire/wheels on the ground or jack under LCA, holding weight of vehicle to push axle out. We only need to pull out on axle, with a 8x1.25 bolt.
Axle needle bearings condition, are very hard to make the call if good or bad. Axle scoring, is best clue, in making the call. This FDS has ~2K miles on it. You can see where needle bearing rode and brass bushing butted.
Notice the scoring where needle bearing rides on axle. It's uneven shading for one and ride in narrow bands. Needle bearing was passed useful life.
Longer story...
I had replaced the knuckle (due to some spindle thread damage), with a used one I had lying around. I did not replace needle bearing or brass bushing, as they looked okay, and I didn't have any new ones around that day. I also replaced FDS, diff outer seal, wheel bearings, checked brake pads & shims, etc.
I had a wah, wah, wah at low speed, afterward, that I hadden notice before. Maybe more of a sha, sha, sha like a rub. Likely present at higher speeds also, but perhaps just couldn't be heard over tire, wind, engine, etc. noises. It seem to be FR (front right).
I was really having trouble isolating the sound. So put on 4 jackstands. Put in D while idling. I crawled under with my stethoscope. Difficult call, but still, seemed to be front LH area at FDS.
I check brake pads & rotor, wheel bearing which were new, FDS outer seal and knuckle rear seal for rubbing, pulled knuckle and checked new FDS which seem fine but toss in another new OEM FDS. Still sound present.
I knew I had made the snap ring gap extremely tight. If fact, I had to tap in to seat in groove of axle. Tapping on having zero gap, is not a good idea. But the only thing that happens, is brass bushing wears until there is some gap. But thinking brass bushing may be making the rub sound. I checked gap after about 1K miles, which it now had some, before pulling knuckle again.
Note: Snap ring gao of >0.20mm, keeps FDS seal pulled into knuckle seal properly. Making water tight seal!
I had looked at outer axle of FDS, where needle bearing rode. It look okay at first. But later, I went back and reviewed the axle picture above, which only had 2K miles on it, I then saw, I missed the scoring. I replaced the needle bearing and sound gone, finally.
@abuck99 did the math some years ago, on expected life of wheel bearings (Timken data). IIRC, he came up with 250K miles. That is, if wheel bearings perfectly serviced. I find axle needle bearings, are almost never serviced (lubed).
. If I pull drive shafts and diff tube to yank that output bearing, I’ll also pull knuckles to install new needle bearings and brass bushings. While I’m burning money, I might as well.
