The axle showing the high heat marks is from the bearings that I found very loose. Claw washers very deeply scored, and snap ring scored and gap very wide (0.60mm). I believe PO used shop that used old school (hand tight) to set preload.
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I've set the torque on wheel bearing adjusting nut really tight this time on LC, as you've noticed. This does concern me, so I'm carry an inferred thermometer with me. I drove ten miles on highway, then ten miles in town. Took reading off hub flange at 78F to 82F with outside ambient temp at ~65F. This was actually about the same temp as when I torqued less with less preload (~7lb). I've been increasing torque over the years, based obtain a higher preload. I've only reached the FSM recommended preload of 9.5 to 15lb recently (2K miles ago).
We had weather coming in which cut me short on time, and I didn't pull & inspect the LC's claw washers this last time with only 2k on them. But each repacked I've pushing preload higher and higher. Each time claw washer has looked better with less scoring, and bearings haven't gotten worse. Scoring indicates chatter.
I'll be replacing the LC bearings & races next repack as they'll have 190K on them and have never looked very good. At least not on DS side where I found loose bearings. This was from lock washer not being bent (PO). That side the claw washer was really scored badly.
It seem the more miles on the bearings the high the torque needed to reach FSM preload. I feel obtain FSM recommended preload is key health of bearing, races, spindle, snap ring, hub flange and axle.
I too wonder about after market axle, but looks pretty good. Only way to know for sure is to set up new after market Interparts front drive shaft, flange, bearings & races and snap ring. Maintain properly and see if it then eats flange.
I do know these things:
PO was poor at maintaining and took to non Toyota shop all to often.
- Front tires worn out with rears good. This indicates wheels not keep properly balanced.
- Claw washer deeply scored/grooved. This indicates wheel bearing to loose leading to wheel bearing chatter IMHO.
- Snap ring gap to wide. This indicates snap ring gap not set properly and/or widen over time do to chatter.
- One knuckle replaced, with no sign of impact. This indicates bearing preload to loose creating chatter, damaging bearings, race & spindle. Which feel & sounds would have alerted anyone attuned to that sort of stuff, which I am.
- Drive shaft outboard seals both damaged. This may have been from after market parts, or from excess movement and vibration.
- Both front drive shaft replaced at some point. Signs of old CV joint lube around boot seam area of frame & body. Neglecting boot leak caused failure or someone just found it faster to swap front drive shafts then reboot. Boot leaking was probably brought on early, from poor maintenance leading to excess vibration.
Talking with a Toyota shop mechanic he said: Loose wheel bearing lead to chatter, eats claw washer, widens snap ring gap and excesses vibration. In out movement of axle and hub with this chatter starts eat at teeth of hub flange & axle. This leads to the clunk from neutral to drive.