Differential bearing?

[Somewhere]

I'm on our first big trip with the family in our 89 warrior. (florida to the great nw)Started hearing a howl last night. Today leaving New Orleans it has become unbearable. I have checked the wheels and even jacked up the front and do not think its the wheel bearings. Checked u joints and made my way to the rear end. Carrier bearing seems sound but when I got to the front of the differential it is hot leading me to think its the bearing. No grinding or clunking noises so I'm really hoping its just the bearing.

My questions are. Do you think I'm correct in my diagnosis? WilI we be able to get this bearing? What type of shop should I take it to for the work to be done?

I tried searching the archives as to not ask the same questions over and over but may not be wording my search right. Anyway I'm overnighting here and hope to figure something out in the morning.

Thanks for any help.

[Odyssey 4x4]

I had a similar problem in an old Ford Bronco I had years ago. It drove normal but had a pretty bad howling sound from the rear end. Being a careless high schooler, I drove it all the way till it crapped out (opened the diff to chunks of metal falling out).

I'm sure the bearing can be easily located. If you can't locate one for your specific vehicle from an auto place, mostly any type of construction heavy machinery place will be able to locate it off of the number that is stamped into the bearing. The same usually goes for seals. Any mechanic should be able to fix it considering it is just a Toyota 1 ton pickup. Worst case worse, you can replace the entire rear end replaced like I did in the bronco. Although I'm the type that can be found in a junkyard in 100 degree weather laying in the dirt under a truck pulling parts off of it that I need.

Try not to drive it before fixing or you can risk chewing up the differential which will be quite a bit more to fix.

Good luck.

[Maineah]

How is the gear oil level? Be a good ideal to check it. There are two back to back bearings on the pinion gear and the preload must be set correctly this means that the jack pot needs to be out it's not just a matter of throwing a bearing in if that is indeed what's wrong.

[Odyssey 4x4]

I checked my diff fluid the other day and it was quite low. Always a good idea to top off.

[Somewhere]

How is the gear oil level? Be a good ideal to check it. There are two back to back bearings on the pinion gear and the preload must be set correctly this means that the jack pot needs to be out it's not just a matter of throwing a bearing in if that is indeed what's wrong.

Oil level should be good. No signs of leaking and checked it before I left Florida. Unfortunately that is one size socket I did not throw in the tool bag so I won't be sure until tomorrow.

Two bearings. I'm trying to see it in my head. Any pictures you know on the web? Any chance its just the one in front? Can one be changed or does it need to all come apart to make that happen?

Ok rereading I'm lost at the preload. This certainly isn't my at my level of expertise.

No drive train specialists in this area plenty of transmission shops. I'm not sure who to call.

[5Toyota]

some trans shops do rear e nd work some do not. the gears and bearings must be checked with dial guages it is a complex job. and some trans shops are no good at al l just rip off shops. most of the pinion gear sets use a collapsable spacer under the pinion nut to my knolage that must be replaced as well if is the least bit off it will howl very bad. DID YOU CHECK THE PINION NUT never had any trouble with them coming lose on a toyota. but did on a datsun i had all came apart.

[zero]

I'm on our first big trip with the family in our 89 warrior. (florida to the great nw)Started hearing a howl last night. Today leaving New Orleans it has become unbearable. I have checked the wheels and even jacked up the front and do not think its the wheel bearings. Checked u joints and made my way to the rear end. Carrier bearing seems sound but when I got to the front of the differential it is hot leading me to think its the bearing. No grinding or clunking noises so I'm really hoping its just the bearing.

My questions are. Do you think I'm correct in my diagnosis? WilI we be able to get this bearing? What type of shop should I take it to for the work to be done?

I tried searching the archives as to not ask the same questions over and over but may not be wording my search right. Anyway I'm overnighting here and hope to figure something out in the morning.

Thanks for any help.

If you disconnect the driveshaft and then spin the pinion-flange by hand - you'll feel it if it's bad. Failure at the pinion bearing is common after someone has installed a new oil seal (repair gone wrong). Any work been done on it lately? Toyota uses a crush-collar inbetween the pinion bearings - so all it takes is for someone to over-tighten that pinion nut to ruin the bearings.

If the pinion bearings are bad, it can be repaired without any special tools, dial gauges, prussian blue, etc. New bearings, new oil seal and a new crush collar would likely be needed.

Note that if the rear has been run low on oil and the ring and pinion gears got "scorched" they can also howl and will do so forever until replaced.

[Maineah]

Just because you don't see a leak does not mean it isn't if you find it low the next step is to pull the hubs and make sure it's not all over the brakes. If it's low and has been run too long you'll never get rid of the howl with out a ring and pinion set but it does not hurt to try and see what happens.

[Somewhere]

If you disconnect the driveshaft and then spin the pinion-flange by hand - you'll feel it if it's bad. Failure at the pinion bearing is common after someone has installed a new oil seal (repair gone wrong). Any work been done on it lately? Toyota uses a crush-collar inbetween the pinion bearings - so all it takes is for someone to over-tighten that pinion nut to ruin the bearings.

If the pinion bearings are bad, it can be repaired without any special tools, dial gauges, prussian blue, etc. New bearings, new oil seal and a new crush collar would likely be needed.

Note that if the rear has been run low on oil and the ring and pinion gears got "scorched" they can also howl and will do so forever until replaced.

Thank you that's great info!

I managed to check the fluid this morning before leaving camp. Everything looked good and no signs of metal shavings.

I'm at a shop now and hopeful they have a handle on these type of repairs. They are a complete transmission shop and seem well informed.

If I need to replace parts in the rear end how do I look up parts? Was this same differential used on any of the traditional toyotas? Will I be able to find bearings seals etc...

[zero]

Thank you that's great info! I managed to check the fluid this morning before leaving camp. Everything looked good and no signs of metal shavings. I'm at a shop now and hopeful they have a handle on these type of repairs. They are a complete transmission shop and seem well informed. If I need to replace parts in the rear end how do I look up parts? Was this same differential used on any of the traditional toyotas? Will I be able to find bearings seals etc...

The differential "center section" is not special for the full floater as compared to the lighter semi-floaters. They DO change over the years though. If a pro-shop is working on it - identifying the parts is easy by measuring and the existing parts #s. The bearings at least will have #s on them. The seal is easily measured if there is on it. Also easy to go on-line, get the Toyota #s, and then use those numbers to buy from a non-dealer auto parts seller.

80s-90s like used in your RV - if using NAPA #s -will have an SKF seal # NOS 14767 pinion oil seal, a BR30306 outer pinion bearing assembly and a 32307A31 inner pinion bearing assembly.

Pinion seal should have a 1.49" ID, 2.91" OD and .44" thick. Getting a new crush-collar is must. Advance Auto has it under the Motive brand with part # 3114.

I'd shop around for the parts though. NAPA prices are often way too high.

[MontanaChinook]

Yeah sometimes the pinion bearing will loosen up, but I'm not sure it would cause howling. Just vibration. Not positive, though!

On the pre-84 pickups they used a reusable solid spacer instead of a crush sleeve, which is nice. Doesn't relate to your truck though...

[zero]

Yeah sometimes the pinion bearing will loosen up, but I'm not sure it would cause howling. Just vibration. Not positive, though!

On the pre-84 pickups they used a reusable solid spacer instead of a crush sleeve, which is nice. Doesn't relate to your truck though...

I can confirm that a loose pinion won't make it howl. I've had to tighten up many that were very loose. Ran smooth and not noisey but leaked oil. What I've seen happen many times - is a guy with a air-gun taking off the pinion nut, replacing the seal, and then reinstalling that nut with the air-gun. If the rear had a crush-collar inside - it will "over-crush", put too much preload on the bearings and they then burn out as soon as you drive down the road. Once burned they howl like crazy. The proper way to do it - #1 - mark the nut before removing and then when reinstalling tightening it 1/8 turn past where it was originally. Or #2 - use a dial indicator measuring end-play and tighten until correct and then stake the nut. With units that came from the factory with internal shim-packs instead of crush collars - you can tighten up just fine with no fear of damaging the bearings. The shims prevent the bearing overload.

May all be moot since we don't know what the problem is. Differentials rarely just go bad and start howing. Usually some event causes the problem - like a recent so-called "repair" or being run low on oil. If run low and the ring and pinion gears have what looks like scorch marks - it will howl forever unless the gears get changed. The differential side-bearings can also cause a bad howl.

[Somewhere]

Well I've been here all day hanging at the shop with two kids well you can guess what that's like.

Early today upon arival they test drove the warrior. A lot of head scratching went on after that. One thought after another finally getting the rig jacked up running and with some stethoscope work turns out back right wheel is making noise. Sure enough after pulling the wheel it's obvious the bearing is scored up pretty good.

I was under the impression the rear wheels are grease packed and not lubed from the differential. Now I know that isn't correct I can see why they don't heat up like a bad front wheel bearing will. I still hate the fact the differential was hot to the touch around the pinion bearing. That really still has me worried but for now I have the parts waiting for them to get them on and down the road we will go.

Thank you so much for all the info. Honestly I feel foolish for assuming it was the pinion bearing.

Edited June 10, 2013 by Somewhere

[waiter]

I was under the impression the rear wheels are grease packed and not lubed from the differential. Now I know that isn't correct I can see why they don't heat up like a bad front wheel bearing will.

The rear bearing ARE greased packed, similar to the front bearings.

Make sure the boys working on the rear axle are comfortable with this. If they are doing one side, I would have them do the other side at the same time, That way you know your good.

Pay particular attention to how the Lock plate and Lock Nut engage and are held in place with the lock bolts. Look at drawing RA0660.. One member on this forum had a shop do their rear axle and less than 50 miles from the shop, the hub fell off because they improperly installed the lock nut / lock plate.

John Mc

88 Dolphin 4 Auto

Dully_Rear_End_Overhaul.pdf

[DanAatTheCape]

look at waiter's link closely. he is right -- the bearings are SUPPOSED to be greased & not lubed by differential fluid. Of course that does not mean that a previous owner (or mechanic) though that they knew better than toyota. A recent thread on this BB included a guy doing exactly that.

There is a shop in Orlando who rebuilt the chunk on my 92 spirit itasca (totaled on 2009). Advanced driveline.

Chunk is not that hard to get out (a chunk is the innards of the differential).

Sounds like you have wheel bearing issue though. There are 2 seals on each side - a little one in the tube that is wet (differential) oil & on which the bearing ride on the outset of that tube.

If you fish around you can get part numbers on previous threads in this section. Might as well check the brakes while you are in there too.

BTW, a test I do on my rear end is after a highway section touch (feel) the hubs & the differential housing. They wheels should not be too hot (unless you have been hammering the brakes which is not necessary on these units if you just take your foot off the gas before you get to the light) , The differential can get rather warm on warm days - should not be too hot to touch but if it is warm enough that you really do not want to hold your hand on it, time to think about it.

on my camper (93 winnie warrior), a 24 MM socket opens the fill (check) hole on the differential.

[Somewhere]

Well I made to the hill country in Texas. Unfortunately they only did one side and didn't finish until 5:30. I will consider having the other side done on the trip but hope to make it and take care of it at home. Starting to hear an exhaust leak around the manifold also hope to let that go till we make it home.

I think he was pretty thorough and certainly packed the bearings before installation. Replaced both seals iner and outer bearings with new races.

I'm exhausted so I may add more tomorrow right now I'm just thankful and sleepy.

I checked out the diagram and everything looks good. (I think)

Thanks again everyone! I really appreciate the support.

[Maineah]

Gear oil is a far better bearing lube then grease. Toyota uses a small seal in the axle tube to keep the gear oil from reaching the bearings why they did this is beyond me but if the bearing was full of gear oil that is not why it failed most likely it was because it had not been greased and is full of oil now because the bearing failed and trashed the seal. There are big trucks on the road right now with a million miles on them with gear oiled bearings that have never been touched. Toyota and as some have said some Nissan's are the only ones that have greased bearings. I hope the shop doing the repair does the other side as well.

[zero]

Gear oil is a far better bearing lube then grease. Toyota uses a small seal in the axle tube to keep the gear oil from reaching the bearings why they did this is beyond me but if the bearing was full of gear oil that is not why it failed most likely it was because it had not been greased and is full of oil now because the bearing failed and trashed the seal. There are big trucks on the road right now with a million miles on them with gear oiled bearings that have never been touched. Toyota and as some have said some Nissan's are the only ones that have greased bearings. I hope the shop doing the repair does the other side as well.

The 87 dually box-truck I scrapped had the inner seals removed in the rear-axle. I can't say how many miles it had been used that way but I know if was a lot. Bearings on both sides look like new. I'm not recommending that anyone do it - or not do it - but I agree with your comments 100%. I've worked on heavy-equipment most of my life and do not recall EVER finding a failed bearing in a full-floater that had wet wheel bearings.

My take is . . . to say that it MUST be the way Toyota did it is absurd. With that reasoning, nobody would ever update, improve, or modifiy anything, anywhere.

The only possible reason that I can think of - to have "sealed" wheel bearings in back - is when a rear-axle is designed in such a way that the center section and the end-bearings are not in the same plane and lube will not travel as needed. Certainly not the issue with the FF used in Toyotas and Dynas. They are set up almost exactly like the HD Dana/Spicer rear axles that do not seal the wheel bearings. Somebody argued earlier on this forum that there is no passageway for oil to get from the center to the ends. That is absurd. Someone else argued that when the inside seals are omitted - the brakes get full of oil This too is rediculous.

#2 wheel bearing grease is simply 30 W motor oil mixed in a medium like clay or lithium soap. When bearings are sealed and packed with grease - they must be taken apart and repacked at certain intervals. A non-sealed rear axle also uses 30-40W oil with EP additives - but the gear-oil viscosity rating system is used and what would be 30-40W motor oil - is called 80-90W gear oil.

If someone has a desire to run open wheel bearings that get full-time lube - the one factor that needs to be verified is how high the oil-level check-plug is in the center-section. It must be high enough so oil will travel through the tubes a bit when level. In reality, since trucks get driven on all kinds of uneven surfaces the oil finds it way to the ends anyway and the hubs on each end serve as reversoirs.

[zero]

Chunk is not that hard to get out (a chunk is the innards of the differential).

I've worked as a mechanic on big truck and HD equipment for ove 40 years and have never heard the term "chunk" used in my area to describe a differential assembly in the center of a rear-axle. Don't know if "chunk" is regional term or something that evovled just lately? I bet if you called a few old-time junkyards - at least in the North-East - as asked for new "chunk" - there'd be some head-scratching going on.

The Toyotas use Hotchkiss type removable center-sections. Many other vehices use Salisbury center-sections. "Hotchkiss" refers to a rear axle (like many Toyotas and Fords use) that comes out as an assembly. If it needs rebuilding you can remove the entire unit, stick it on your work-bench and service it. "Salisbury" rear axles have an access plate that comes off and all service work has to be done in-place. Many semi-floating rears like GM 10, 12, and 14 bolt rear axles and many Dana/Spicers use this design. Hotchkiss design came from France and Salisbury came from New York in the USA.

Is "chunk" a generic term used for any internal differential or rear-drive parts - or is it just for Hotchiss center-sections?

[waiter]

As JD and others have mentioned, This axle would probably be OK without re-pack, as long as they are lubed from the differential, (the small inner seal must be removed to allow differential vapor and oil to reach the bearings.

That is the problem - most mechanics have never seen this setup, and just assume the bearings are lubed from the differential, and don't know about the small inner seal. So when they put it back together, they don't re-pack, and they don't remove the inner seal, and the bearings burn up from lack of lube.

The only headache, if someone else does the work, this lubrication process is so unusual, you must make sure the mechanic who does the work knows specifically what to look for, and will follow the instructions, I want the bearings re-packed.

Personally, I re-pack, and leave the inner seal in place. Its worked for this many miles and I'm not willing to run Toyotas R and D department on differential vs packed lubrication.

John Mc

88 Dolphin 4 Auto

[zero]

I got curious and compared a Dana HD70 FF 10.5" axle assembly to the Toyota FF 7.8". The Dana has the oil level about 1" above the bottoms of the tubes. The Toyota is 1" lower and level with the tube bottom. If someone wanted full-time oil lubed bearings - seems the oil level in the Toyota axle should be raised by 1". Easy to do. just stick an elbow in there and raise the filler plug.

[DanAatTheCape]

here we go again - a discussion about re-engineering the rear end.

there is one BIG difference in the design of the wheel bearings in this rear end - the bearings are outside the axle tube (as opposed in inside) - that means even if differential oil gets out the tube to the bearings - distribution there after is questionable at best.

also worth noting that the brakes are interior to the bearings. If the little seal is left out then only the inner seal would keep the bearings from getting an oil bath.

having being into 2 sets of these I will certainly recommend going with the design from toyota.

[Maineah]

The oil does flow down the axles from the rotation when you remove an axle from a "normal" full floater it will be wet end to end. The new or dry bearings needed to be packed to keep them from burning up when installed but the gear oil will wash the grease out and they will run a very long time bathed in oil. As I say I have no ideal why Toyota does this guess they figure the grease will out last the brakes. When I was young seals were made of leather (Chicago Rawhide) and yeah they leaked when they got old all over the brakes but by the time Toyota put them under small trucks the seals were synthetic and would last hundreds of thousands of miles.To me a full floating rear should need no service for at least a 100K even in a light truck brakes and all. I guess this discussion has been going on for many years from people who know trucks and the only thing they can do scratch their heads.

[zero]

here we go again - a discussion about re-engineering the rear end.

And according to you changing something is always bad?

there is one BIG difference in the design of the wheel bearings in this rear end - the bearings are outside the axle tube (as opposed in inside) - that means even if differential oil gets out the tube to the bearings - distribution there after is questionable at best.

That is nonsense. The Toyota design is virtually a carbon-copy of the Dana FF axles. The placement of the bearings outside the tube is the same as thousands if not millions of full-floaters all over the world that use common lube for the center section and the wheel bearings on the ends. I don't know of ANY full floaters that have bearings inside the tube. Enlighten me. That sort of setup is usually with semi-floaters that use needle or roller bearings at the tube ends - like Dana 44s, GM corporate 10, 12 and 14 bolt axles, etc.

also worth noting that the brakes are interior to the bearings. If the little seal is left out then only the inner seal would keep the bearings from getting an oil bath.

Yes and again - just like the vast majority of full floaters used all over the world with just one seal keeping the oil from the brakes per side. Also note that "1/2 ton" 5 lug Toyota semi-floating rear axles with sealed ball bearings on each end also only use ONE seal per side to separate oil from the brakes. If you see THAT as a problem - then I guess you feel Toyota needs to re-engineer all their smaller axles?

I'm going to infer from your comments that you don't have much experience working with HD rear axles?

[Maineah]

here we go again - a discussion about re-engineering the rear end.

there is one BIG difference in the design of the wheel bearings in this rear end - the bearings are outside the axle tube (as opposed in inside) - that means even if differential oil gets out the tube to the bearings - distribution there after is questionable at best.

also worth noting that the brakes are interior to the bearings. If the little seal is left out then only the inner seal would keep the bearings from getting an oil bath.

having being into 2 sets of these I will certainly recommend going with the design from toyota.

No, the Toyota rear is exactly the same as any other full floater except for the small seal in the axle tube and the small machined seal surface on the axle. But this is from some one that has only had maybe a hundred of this type of rear apart Toyota's included. Even a 1/4" of gear oil is far better then a pound of bearing grease. No one will ever convince an old time mechanic that this was a good ideal. Right now you'll not find a new full floating axle that does not have gear oil lubed bearings.

[zero]

Even a 1/4" of gear oil is far better then a pound of bearing grease.

Yes - grease consists mostly of the medium that holds the 30 weight motor oil in suspension. Soap, clay, etc. A typical pound of #2 grease only has 2-6 ounces of lube oil in it. A pound of gear oil has - well duh - a pound of gear oil in it.

I don't believe Dan-at-the-Cape has much actual experience working with rear axle assemblies.

By the way - the majority of older track-driven equipment had grease-filled bottom rollers on the tracks. Oil was not used since the older seal systems did not keep oil in all that well. By the mid 1970s - all the greased-rollers were phased out and since then - they are all oil-filled. Life is MUCH longer with the oil lube. Ask anyone who owns or who has ever worked on a bulldozer or tracked excavator.

[waiter]

My experience with a FF is precisely one. The Toyota.

I believe the ongoing discussion regarding Lube systems (pack vs differential) is academic, and not advice to change the existing system.

If someone wishes to do Toyota R and D and prove the longevity of the axle using differential lubrication, get back with me when you see several million miles on a fleet. To date, the Toyota fleet has racked up millions of miles with no record of failures in the current lubrication system.

Packed bearings have been used on trucks for years - Look at the front axle, AND, look at trailer axles. all packed.

Advantages /disadvantages

I still need to pull the wheels off every 30,000 to inspect brakes, thats a great time to repack the bearings. Good quality grease will last 50,000 - 100,000 easily

With differential lube, any bearing failure (or metal failure) will contaminate the lubricant and could cascade into the rear end and the bearings on the other side.

I see the biggest risk as the "Unique Factor" - This system is unusual, as such a mechanic may never have seen one, and could reassemble after a brake inspection without repacking, If the inner seal hasn't been removed, the bearing will not be lubed, and failure is imminent.

John Mc

88 Dolphin 4 Auto

[zero]

Packed bearings have been used on trucks for years - Look at the front axle, AND, look at trailer axles. all packed.

No - not all trailers have grease-packed bearings. Many have oil-filled assemblies.

But yes - many cars and trucks have grease-packed sealed bearings. Some you can take apart and repack and some you cannot and can only renew.

I agree that anything rolling should be checked on occasion. In the real world - many people never check anything. They just drive until something makes noise or stops working. In that situation- the oil-lubed bearings will easily outlast grease-packed bearings.

One advantage to oil-filled that I personally like. If a seal leaks - you get oil on the ground and you know it.

With grease-packed bearings? If a seal leaks - you get no warning, the grease and bearings get contaminated - and fail.

[zero]

AND, look at trailer axles. all packed.

Just about all heavy-duty over-the-road trailers use oil-filled bearings now adays. Here's one link to a PDF that descibes the setup. They have been tested for millioins of miles and have greatly outlasted grease-packed bearing assemblies going by many fleet-owner reports.

http://www.americasbesttech.org/files/Download/Manual_Hub_Service_Manual.pdf

[waiter]

JD, Thanks. I'll stick to the Toyota packing procedure, but if the inner seal gets buggered up, I won't loose a lot of sleep.

John Mc

88 Dolphin 4 Auto

[zero]

JD, Thanks. I'll stick to the Toyota packing procedure, but if the inner seal gets buggered up, I won't loose a lot of sleep.

John Mc

88 Dolphin 4 Auto

I just went though my FF Toyota axle and put in two new seals per side and packed the bearings. Not because I believe the OEM setup is better or worse then an open system. I just don't feel like experimenting and also know that I'l be checking things over the years. Besides - a sealed and grease set of bearings is good for at least 30-40K miles and by the time my Toyota gets driven that far - I might be in a wheel-chair or dead.

[waiter]

^ Me Too :-)

John Mc

88 Dolphin 4 Auto

[Maineah]

Toyota puts small plastic plugs on the edge of the backing plate that you can remove and have a look at the brake linings that being said I would not have to worry about my bearings if they were oil lubed if there was plenty of lining on the brakes Metal will contaminate grease also one of the best way to find out if the greased bearings are failing is to wipe them with a clean rag and look for shiny stuff it just sticks in there. The oil around the wheel bearings pretty much stays put in a full floating axle it does not travel around. When I worked in a gas station/repair shop in the 60's front wheel bearings failed a lot seen them twist off the spindals or at least spin and trash them. Just about every thing now is front drive with sealed bearings and hubs with bearings. Front brakes usually wore out before the bearings that was a good thing because the grease just would not cut it for more then 30K. I'm not suggesting that every one should remove the seals just trying to point out it's a dumb ideal and Toyota is not above doing dumb things.

[DanAatTheCape]

some one earlier in this thread questioned my experience- i have done 2 brake jobs on toyota campers & have had one chunk gone thru. I have worked on my own vehicles all my adult life - clutches, brakes, timing belts, shocks, starters, generator s etc.

I just do not see any reason to experiment by removing the inner seals. I see a good reason to NOT do it - you can see it too if u pull an axle shaft & envision the path the oil has to take to get past the lock nut & first race. -- looks like NOT a good idea to me.

But to each their own - I will pack my bearings & install the seals. I KNOW that works.

[zero]

some one earlier in this thread questioned my experience-

Yes, I did. I did not make "judgement" but did question your overall knowledge. That because some of your comments incicate otherwise.

You stated . . "there is one BIG difference in the design of the wheel bearings in this rear end - the bearings are outside the axle tube (as opposed in inside) - that means even if differential oil gets out the tube to the bearings - distribution there after is questionable at best."

The reality is - virtually ALL full floaters are designed that way. There is no "big difference" in the Toyota design as compared to other FF design. Distribution is NOT questionable. It has to happen because oil sloshes around in a moving vehicle and the whee-hubs on each end act as independent oil reservoirs.

You also stated . . .

"also worth noting that the brakes are interior to the bearings. If the little seal is left out then only the inner seal would keep the bearings from getting an oil bath."

That of course is true. It is also true with the vast majortiy of all cars and trucks with semi-floaters or full-floaters. Even the semi-floater Toyota "1/2 ton" only has one seal separating gear oil from the brakes.