Newbie axle/diff/bearing questions (long)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.


Sep 17, 2002
a valid location
Went wheeling today in my Cruiser (1990 FJ62 135k miles stock drivetrain), pulled an FJ80 out of a big mudhole. During the pull and then on the way up the hill out of the hole myself I heard an intermittent high frequency grinding noise (it sounded exactly like when I pressed the 4WD button once last winter with the hubs unlocked). I was in 4 low, under load, constant throttle, front wheels straight ahead, some wheel spin but making good headway. Drove home in 2WD. Here's what I found:

The grease in the locking hub is no longer the red wheel bearing grease I packed it with a couple months back when I replaced the wheel bearings, seals, and brake rotors. It is now gray-green and opaque. The locking hub and the end of the axle shaft looks fine, so I don't think the noise came from there.

The grease around the outer wheel bearing was rusty! The rest of the grease in the axle hub was still red but creamy, except around the inner wheel bearing, where it looked fine - still red and translucent. The outer bearing is burnt but otherwise fine (no gouges, spins freely), but I'll replace it. I did find one piece of (metallic?) grit near the outer bearing while cleaning out the hub.
There was no rust in the locking hub. All of the gaskets and seals (inner wheel grease seal, hub body gasket, hub cover gasket) look fine - they are almost new (as I said above I replaced all this stuff a few months ago).


Could the wheel bearing have been the source of my noise?

Where did the water in the outer bearing come from - did it come from the knuckle and travel into the outer wheel bearing through the slot in the top of the spindle? I did squirt some black moly-lithium grease into the knuckle at the time of the brake service, so this is the grease that's making it into the locking hub I think.

Does this mean I have water in my knuckle?

What next? - knuckle/axle rebuild?

thanks for any pearls of wisdom..
Here's my next noob question.

Truck (FJ62 stock drivetrain) is up on jack stands, DS axle hub/rotor is off, PS fully assembled. Should I be able to spin the axle shaft freely by hand, or should the driveshaft turn when I do this? I can spin mine freely in either direction. PS hub is unlocked. The axle shaft feels a little clunky intermittently while turning by hand.

Next situation: Locked the PS hub - when I spin the PS tire the DS axle shaft spins the opposite way. This is reassuring to my noob brain. If I spin the DS axle shaft by hand now the driveshaft turns. Also reassuring, I think.

Is this normal diff behavior? (I'm trying to figure out if the noises I heard maybe were from the diff). Be gentle.


Bearings don't make a high pitch grinding noise; they make a low freq whirring or rumbling noise. The drive shaft behavior is normal for an open differential. Put the wheels back on with each wheel off the ground on jack stands and run it in 4th gear and listen for the noise from the outside to help localize it. You can use a broom stick to conduct noise to your ear to localize it further.
No results from that experiment. Put everything back together (repacked the wheel bearings and axle hub with fresh grease, cleaned and reassembled locking hubs, etc.) and drove the truck to Sears and bought two more jack stands. Jacked her up on all four, ran her for a while in every gear - no weird noises other than the tranny shifts kind of hard in this situation, which is to be expected. For some reason the DS front wheel doesn't turn as fast as the PS. Probably I overtightened the bearings a little bit or the PS is too loose. Held a broomstick against everything and it all sounds the same - just a high pitched whine. Put her back on the ground and did a little bit of light wheeling and couldn't reproduce the sound. When I was on the trail today I was under heavy load (pulling an FJ80), going up hill, in wet sand, with lots of throttle - hard to reproduce on jack stands.

I also discovered that I now have 2 low available. I'm not supposed to - the FJ62 is supposed to shift into 4WD automatically when you put it in low. Mine used to but now it doesn't. I'm worried about my transfer.... ??? :(
I dont recall that the 62 vac case shifts into low automatically when you move the lever. it might but I have not seen it on mine. The dash button engages the 4wd, IE the ft cone vac assy controlled on the PS firewall. The lever moves it from hi to low while still in 4wd. I have never tried it but I dont see why you could not get 2WD low by moving the lever but not hitting the switch. IIRC the 62 case is a vac off case in that the 4WD will be engaged unless the vac is cut off buy the firewall solinoid. I would check the 2 vac hoses that go to the case. The noid on the firewall goes out often. Switch the hoses to get it to engage, you are bypassing the switch. The original grinding sound I would guess comes from the 4wd not being 100% engaged or it is loosing vac. Check the vac hoses on both ends. Squealing sound could be anything. The bearing issue sounds like bad inner axel seals.
Thanks. BTW, it says right on the glove box that it should shift into 4WD automatically when you shift into low. I don't mind having 2 low available - it's kind of cool.


Users who are viewing this thread

Top Bottom