Anyone EVER repack their REAR wheel bearings? (1 Viewer)

[Rich]

My guess would be that the gears in the diff see much higher pressure than the wheel bearings.

 

[cruiseroutfit]

I haven't looked into it, but it's my assumption that a bearing grease (vs oil) is engineered to handle the high pressures of a loaded low speed bearing such as the rears on an FF, where gear oil being thinner doesn't provide that level of protection for high metal to metal pressure. I would be interested in hearing whether this is in fact true. After all, I'd think that the gear oil is handling some pretty high pressures with the diff gears, etc. Dunno.

I know of at least one other 80-ish application where Toyota chooses grease and another mfr switched to gear oil. Land Rover (I know, I know) switched to gear oil in their birfields at some point years ago. Wouldn't it be nice to change out your birfs by removing a drain plug and filling it like a differential? Of course, there are some down sides to the LR approach, but just another data point.

As Robbie points out, my rear bearings did get a bit loose and put some machined marks on the rear spindle/axle housing. This was on the 93, which was used for some heavy towing with just gear oil (washed all grease out) in the rear bearings for a couple years. I didn't seem to have any trouble getting the bearings to set up correctly when I repacked them, but as mentioned above curiosity has now taken hold and Cdan's sending me a rear seal kit so I can dig in and have a look see. Will post results.

OTOH, that machining damage happened by 90,000 miles yet my 97 had 137,000 with oil - washed bearings and not a trace of a mark. So, some evidence to attribute that damage to the presence of gear oil (vs specc'd grease) when the vehicle's being used heavily on the rear axle. My 97 was just a mall cruiser, and rear bearings awash in gear oil may be just fine based on my findings, but I wouldn't tow with it like that.

DougM

DougM

Great points Doug, I may be able to answer those in the future (taking a lubrication class as an elective towards my ME degree @ the U of U).

Gear oil is used for BIG industrial FF axles and bearings, and as you noted, they seem to do just fine. There was a thread regarding a guy using gear oil to lubricat his birfs (on an older FJ40), kindve interesting approach, and obviously Toyota didn't design the felt wipers to handle viscous oil...
https://forum.ih8mud.com/showthread.php?t=23105

As I mentioned above, there are some Cruiserheads (Cruiserbrett? Devrodog?) that were using this method, as I recall some of them had some high milage on the setup with tasteful results. Hopefully one of them will chime in...

 

[IdahoDoug]

Yeah, would be interesting to hear from them.

It's a difficult analysis as the big rigs may have correspondingly HUGE bearing surfaces and a pressure per square inch of bearing that's actually LESS than a loaded 80 simply because they center their design solely around absolute durability. WHereas on the 80 there was only so much room to put a bearing there before you have to start enlarging the housing, custom making the bearings/races, etc. Which is simply speculating the 80 stuff was DESIGNED to use grease, where the big mining rigs were designed so sturdy they could choose to use oil instead due to massive over built bearing sizes.

 

[cruiseroutfit]

Yeah, would be interesting to hear from them.

It's a difficult analysis as the big rigs may have correspondingly HUGE bearing surfaces and a pressure per square inch of bearing that's actually LESS than a loaded 80 simply because they center their design solely around absolute durability....

I thought of that too... though some of the domestic FF's don't use to big of bearings realative to the trucks they were found on (FF14B, D60, etc).

 

[IdahoDoug]

Wonder how the domestic FF designs hold up vs the 80s? On the one hand, changing the diff oil also changes the bearing oil, but this may simply be the domestic maker's way of making sure they get beyond the warranty period before the real shortcomings of oiled bearings come to light. The Toyota's grease replenishment and seal replacement chore assures the bearing gets properly reset every service interval, also. The domestic setup means you never have to look at the bearings, but we all know the bearing will get broken in and develop slack. So, which is better? As easy as it is to repack the 80's rear bearings, I'd have to say that is only a minor inconvenience for a system that makes you look at them and reset their play each time. Dunno.

DougM

 

[cruiseroutfit]

Wonder how the domestic FF designs hold up vs the 80s? ...

Did any of the domestics see wide use over 100k

 

[zebrabeefj40]

I've got a FF dually 14bolt under a '93 GMC 3500 Vandura rated for 10K GVW. 194K miles with no issues AFAIK...uses nothing but gear oil for lube. I think there's still oil in there. 12K miles since I got it and I haven't bothered to check/change it yet!

HTH,
Nick

 

[IdahoDoug]

Nick,

Not to rain on your parade, but how do you know it's not on its third set of rear wheel bearings, having only owned it 12k? The three 80s I currenty maintain have 145k, 137k and 288k - all on their original rear bearings.

No offence intended, the Vandura 3500 is a nice workhorse.

DougM

 

[zebrabeefj40]

I don't yet...you got me there. But then the family has had 30 some years of mostly GM vehicles ALL with well over 150K miles and no rear axle issues EVER. Literally never pulled a cover, same oil since new not even a leaky seal. Most of the GM vehicles in the drive have more miles than 2 outa 3 of your Cruisers. Simply, there is rarely an issue with those bearings.

No offense taken, just that I have not had the "bad luck" with domestic vehicles that everyone claims I'm supposed to be having.

Nick

 

[cruiseroutfit]

...Most of the GM vehicles in the drive have more miles than 2 outa 3 of your Cruisers. Simply, there is rarely an issue with those bearings....

Not 2/3 of my Cruisers , I have some hi-milers (282k on my first 40, ~150k on my current 40, 177K on the 62 I just picked up, >300k on a couple) none of which were FF though.

You must have different domestic axles than the ones around these Parts... every truck around town has a leaky diff... (And yes, have driven/owned plenty of domestic axles, I tow with a 04' Dodge, it has a leaky diff ).

Never changed the diff oil after 150k.. now that is wise... I can see waiting to repack rear wheel bearings, but diff fluid, poor ring and pinion needs some love.

 

[scottm]

inner bearing will start to spin if too loose and will then machine a new surface on the spindle

My wife's 80's front spindles showed faint evidence of wear, that made me nervous. I wish I'd put the new races on with bearing retainer just in case, though it would've been a challenge to get all the grease off the inner bearing surface to get it to bond. I'll use it on the rears when I get to it.