Back Brakes and Bearings

[waiter]

There has been discussion regarding if the rear bearings are packed or lubed.

In my case, the back bearings must be packed, they do not get lubrication from the rear end.

Remove the axle drive bolts and tap on the axle, it will pull out.

1) This exposes the inner keeper.

2) remove the two philips keep screws (may need an impact driver)

3) The keep can then be unscrewed from the axle. I used a flat screwdriver to tap the three lugs.

4 & 5) Once the keeper is unscrewed, the hub will pull off, and the bearings will fall out.

6) exposing the axle.

7 & 8) the inner bearing is held in place with a grease seal.

9) The outer bearing and keeper can be seen.

[Derek up North]

1 - There doesn't appear to be a 'Service Interval' or 'Technical Service Bulletin" published by Toyota to repack the rear bearings;

2 - I assume that, like all other wheel bearings I've known, they'll give plenty of audible warning before failing disastrously.

3 - It makes good sense (to me at least) to clean , inspect and repack (or replace, if required) when you have to go 'in there' to do the rear brakes.

I've enough things on my 'To Do List'. But thanks for posting the excellent photos.

[waiter]

These inspections build my confidence factor in the MH.

So Far, everything I've looked at has been good and well maintained.

I'll be looking at U joints and the aft transmission stuff tomorrow (replacing trans filter)

Looks like I have a good machine for the Alaska Trip.

Oh Yah, Forgot to mention that the air bags are pumped up to 90 psi and holding :-)

[Maineah]

Is there a seal inside of the axle tube? If not the oil is going to run into the bearings as long as there is enough oil in the diff. Yes they need to be packed if they are disturbed, the picture of your bearing shows signs of heating.

[DanAatTheCape]

On 2011-01-08 at 9:10 PM, Maineah said:

Is there a seal inside of the axle tube? If not the oil is going to run into the bearings as long as there is enough oil in the diff. Yes they need to be packed if they are disturbed, the picture of your bearing shows signs of heating.

Yes, I've added some part numbers from notes I took while doing brakes on a 92 Itasca Spirit a few years ago. I referred to the little seal as the "outer- small"

I also attached a photo of some of the seals- the little one is the one you asked about.

[DanAatTheCape]

On 2011-01-08 at 9:10 PM, Maineah said:

Is there a seal inside of the axle tube? If not the oil is going to run into the bearings as long as there is enough oil in the diff. Yes they need to be packed if they are disturbed, the picture of your bearing shows signs of heating.

Yes, I've added some part numbers from notes I took while doing brakes on a 92 Itasca Spirit a few years ago. I referred to the little seal as the "outer- small"

I also attached a photo of some of the seals- the little one is the one you asked about.

[DanAatTheCape]

On 2011-01-08 at 9:10 PM, Maineah said:

Is there a seal inside of the axle tube? If not the oil is going to run into the bearings as long as there is enough oil in the diff. Yes they need to be packed if they are disturbed, the picture of your bearing shows signs of heating.

Yes, I've added some part numbers from notes I took while doing brakes on a 92 Itasca Spirit a few years ago. I referred to the little seal as the "outer- small"

I also attached a photo of some of the seals- the little one is the one you asked about.

[waiter]

Yes, mine is the same as Dan's. There is a seal in the axle tube.

When I pulled the axle, I could see the hub lube up inside the tube and the small seal on the inside of the tube was preventing it from flowing out and into the bearings.

[Derek up North]

Gotta wonder why Toyota couldn't have designed it so that axle oil couldn't lubricate the bearing like so many other designs.

[Maineah]

Well if there is a small seal inside the tube that will stop the oil. If thats the case for reasons unknown Toyota is the only company in the world that thinks grease is better then 90W oil for lubing bearings unlike large trucks that carry tens of thousands of pounds of weight and every other one ton truck made. I have not had mine apart (it only has 30K on it) but if I find a seal it will not be reinstalled. Packing bearings is short term maintenance gear oil is not. I'm not riping on any one other then Toyota that is a dumb ideal the only gain is a slight reduction in the possibility of gear oil on the breaks I'll bet over the years I' have had hundreds of rear hubs off, from Chevys to Peterbuilts and they all have oiled bearings and seldom have I found bearing failures. So if I have miss lead any one I'm sorry but if you have 50K or more on your MH I would pull the hubs and repack the bearings that's a lot of weight for a greased bearing to carry.

[waiter]

The guy thats helping me (or I'm helping him!) wondered the same thing. And when I told him the rear bearings needed to be packed, he said Nah, they get lubed from the rear end. When he seen the seal he said; "I'll be darned, your right". (He works on big rigs, and I'm using his shop while things are slow)

Anyway, there is a gasket on the axle hub, and the rear seal should keep 90 w from leaking.

Before I make this mod, I would check to see if the fluid level in the rear end is high enough to get lube out to the bearings. I didn't see any fluid come out other than what you see in the picture.

In the meantime, I'll repack and make a decision in 50,000 miles from now.

[Derek up North]

I read either here or on the Yahoo Group that someone got gear oil contaminating his brake linings and blamed it on the seal in the axle having failed, allowing gear oil to reach the rear bearings. Of course perhaps some other seal or gasket might have also failed, allowing oil to progress from the bearing to the brake linings. Just something to consider doing any mod to the Toyota design, strange as it appears.

It seems strange to me that if they are indeed only grease lubricated that there was no TSB or Service interval added to repack them at a specified time. I guess that whatever's actually reaching them, there can't have been a great problem with them.

[waiter]

In order to get 90w to contaminate the rear brakes,two seals would have had to fail, the small one in the axle tube (allowed 90w to get to the bearings) and then the large one on the back of the hub (allowed the 90w in the bearings to get outside the hub).

[Derek up North]

Well, that was perhaps the case, but everyone just jumped on the fact that it was the axle/bearing seal that let go.

It's hard to guess/judge based on shop manuals and (even excellent) pictures. Much better to find out by getting elbow deep in grease, as you are.

[waiter]

ALSO - if the seals were damaged.

Obviously, to repack the inner bearing correctly, you need to remove the inner seal, if that seal was reinstalled, or the new seal was damaged when installed, well, that is the problem.

I like to see for myself. especially on important matters.

AND - God Bless Digital Cameras - Anytime I take something apart, I take a gazillion pictures, Its amazing how this has reduced the "Leftover Part Count" after re-assembly :-)

[Maineah]

If you take the rear bearing out you are not going to get the old seal back in with out it leaking so it's best to have a new one on hand and Derek is right if the rear seal is good you are not going to get gear oil on your breaks. Years past they used raw hide seals and they would fail often before the breaks need repair but seals are so good now they last for the life of the truck. If the rear is full of gear oil it will get to the hub in due time, you have to pack new bearings so they make it long enough for the gear oil to get to them. There is a lot of sloshing around in the diff and the rotation of the axle carries the oil to the hubs has been doing so for many decades. I would guess the seal impedes the flow (hence you don't see much oil in the tube) but once it's started it will wind the oil to the bearings if the seal is not there. There is never a lot of oil in the hubs (1/2 pints not quarts) but it's more then enough for the bearings.

[waiter]

Here is a PDF of the rear axle Service Manual

JOhn Mc

88 Dolphn 4 Auto

Dully_Rear_End_Overhaul.pdf

[pcmentor29]

Here's how the oil leaked on mine, Onto the wheel.

That is the dif gear oil made it past the damaged small seal in the end of the axle tube and leaked onto the cylindrical hub cap and then onto the wheel, not on the brakes or the outer bearing.

I see if the shaft 6 hole gasket was good maybe the oil would have stayed (without small seal in place)in the hub and lubed the outer bearing but it doesn't seem there would be enough oil to get the inner bearing all the way through the hub.

Edited May 18, 2013 by pcmentor29

[DanAatTheCape]

Just did the brakes on my 93 winnie warrior. I also can confirm the bearings are "sealed off" from the rear end oil. This is logical if one notes the path the oil would have to take to reach the bearings, unlike in a single bearing rear end as used in most lighter vehicles.

I drove my camper up on 2x8's 2 layer thick on each side, one side at a time. Then I jacked it up from there. Why? At that angle I could do one side (at a time) and no oil leaked from the axle tube. I will add that I would not want the differential oil in my wheel bearings as the grease would be diluted yet not enough grease would reach to substitute for lubrication purposes.

Some part#'s:

Rear shoes Advance (silver) NB523 $19.00, Autozone (Duralast) 523 $13.39. Advance warrants against defects, Autozone warrants against defects & wear - for life to original owner.

Oil seals From Autozone: Timken 226285(large seal) $6.22 each; Timken 710076 (small seal) $4.59 each

Wheel cylinders From Advance - house brand W37654 $16.99 each.

I used a pound of grease in each hub - I replaced the grease in the cavity between the bearings.

[zero]

Just did the brakes on my 93 winnie warrior. I also can confirm the bearings are "sealed off" from the rear end oil. This is logical if one notes the path the oil would have to take to reach the bearings, unlike in a single bearing rear end as used in most lighter vehicles.

I don't see the "logic." There are many full-floating, dual-adjustable bearing rear axles in use and most are not sealed-off from the differential. In fact, the Toyota/Dyna rear axle is the one I know if that is - and they are all of similar design.

[DanAatTheCape]

I don't see the "logic." There are many full-floating, dual-adjustable bearing rear axles in use and most are not sealed-off from the differential. In fact, the Toyota/Dyna rear axle is the one I know if that is - and they are all of similar design.

You have to look at the design carefully. The oil would haev to go out the axle tube, then reverse course & get past the axle nut. In a conventual auto rear end the bearing is fully exposed in the axle tube. Oil can return quite easily.

Maybe you could post more specific info about some other makes that provide your examples. The difference in this one is that the bearings are outside the axle tube - the bearings ride on the outside of the tube, not the inside, hence the flow issue.

[zero]

You have to look at the design carefully. The oil would haev to go out the axle tube, then reverse course & get past the axle nut. In a conventual auto rear end the bearing is fully exposed in the axle tube. Oil can return quite easily.

Maybe you could post more specific info about some other makes that provide your examples. The difference in this one is that the bearings are outside the axle tube - the bearings ride on the outside of the tube, not the inside, hence the flow issue.

There are thousands of trucks all over the world with the exactly same design and using the central sump for lubrication. All the HD Ford, Chevy, and Dodge trucks with Dana/Spicer 25, 60, 70, 70HD, or 80 full-floating axles is one example of many. If anything, the Toyota/Dyna rear is simply a copy of a USA design which is common for Asian products.

You've lost me with the perception of a lube problem because of two adjustable bearings. If the seals were left out, the hubs on each end of he axle would fill will gear oil every time the truck was unlevel or went around a turn. The hubs at the ends - where you put the grease on a Toyota - serve as "self filling" oil reservoirs.

I'm not saying one way or the other is better or worse. I am saying the design is common to all the full-floaters and the vast majority are NOT sealed like the Toyota/Dynas. I only know of one other make in the world that does that.

By sealing it like on a Toyota/Dyna, self-lube is never possible and maintenance schedule must be adhered to. With the unsealed -like 99% of them are - they are lubed virtually forever unless the rear is run dry. The free flowing gear oil is also a better lubricant then grease - which is 30 weight motor oil trapped in a medium like lithium soap or clay. That's why so many bearing assemblies that used to run on grease are not oil-filled for longer-life on heavy equipment. 90W gear oil is also 30W or 40W motor oil as far as viscosity goes, but it's free flowing all the time and also contains EP additives e.g. zinc and phosphorus.

[zero]

Here's a diagram of the Dana 60 used in Dodge, Chevy and Ford 3/4 ton trucks. Dana 70, 70HD and 80 are set up the same and used in 1 ton and 1.5 ton trucks.

[waiter]

If you take your Toyhouse somewhere for service, its unusual for the rear bearings to be packed, makes sure the place your going knows this, and are prepared to repack the bearings and replace the seals. They will tell you NO, they have never seen one like that. Insist that they are about to see their first one.

Bottom line on the Toyota full floating: DO NOT rely on the differential gear oil to lube the axle bearings. They must be packed. If your missing the small inner seal, or its damaged. I would not loose sleep over it, but if you have one, I'd replace it.

Regardless of what the rest of the world is doing, or why did Toyota design it this way, or would it work with differential lubrication, the bottom line is this: The Toyota design has a excellent history when the rear bearings are packed. When the bearings are lubed with differential fluid, the history is unknown.

Bite the bullet, pull the axles, repack the bearings, and while your in there, look at the brakes. Buy a spare sets of seals (they are cheep) that way you'll always have the correct ones that you know will work.

John Mc

88 Dolphin 4 Auto

[zero]

The Toyota design has a excellent history when the rear bearings are packed. When the bearings are lubed with differential fluid, the history is unknown.

I don't disagree with leaving "well enough" alone and not changing things. My point was and still is - the fact that it is a dual-bearing, full-float design has nothing to do with "sealed and greased" being the logical choice. The vast majority of FF axles are not sealed and they are often the most durable parts of HD trucks. If there is a passage for oil to travel from the center-section to the bearings on each end - oil will work fine and most likely is superior to a sealed and greased assembly when it comes to less maintenance and better lube in extreme cold temps. #2 bearing grease does not give superior lube in extreme cold. My 1994 Ford F250 has 320,000 miles on it and has pulled a goose-neck livestock trailer all over the USA. Engine and the Dana 70 rear are still original and wheel bearings have never been touched. Most other major parts have been fixed or changed many times - especially the E40D transmission. My 1969 Dodge Power Wagon W200 hasn't had the rear bearings touched since I got it in 1975. Also a Dana 70 as I recall.

I suspect the one variable one would need to pay attention to if he/she desired to eliminate the seals in a Toyota - is the height of the fill-level plug in the center-section and it's relationship to the desired lube-height in the hubs at each end.

In regard to "proven history" of FF real axles? I've been working as a HD mechanic for over 40 years. I have lots of first hand experience with the durability of US designed FF axles. In regard to Toyota? I suspect there is little "history" out there. They are uncommon. I've seen a few on older Hertz box trucks, worked on a few, and own one right now. That's about it. On the ones I've worked on, two had failed bearings due to water intrusion and lack of lube. I can't say I've ever seen that happen in a FF rear that got constant lube from the center-section. With a Toyota sealed unit - if the bigger seal leaks - and let's water in -you don't know it until it's too late. With a unsealed FF axle - if that seal leaks - it drips oil on the ground and gets on the brake linings so you notice pretty quick.

The FF rear I have now came out of a 1987 Toyota box truck. It had no seals on the axles(the small seals). Seems someone removed them long ago. I can't attest as to when but seeing how the brake linings were worn down to nothing - I suspect it had a lot of miles on it that way (no seals). I put them back in and greased the bearings that looked flawless and like new. Not because I think it's better this way. I can't really say either way and I don't feel like experimenting.

When sealed and greased - I'm sure it's good for 60,000 miles and I'll probably be dead or in a nursing home before that happens.

I suspect that the design that the FF design that Toyota/Dyna uses was copied from US design axles and then "tweaked" to make it their own. That's not meant as insult to Japanese auto tech. They are well known for taking something elsewhere that works and copying it - instead of trying to "reinvent the wheel." Most of the major USA auto and truck innovations originally came from Europe; especially France. So we copy things too. "Hotchkiss Drive" is from France. So is the "Panhard" rod. The "MacPherson Strut" was created from suspension designs taken from French and Italian cars. Same for overhead camshafts. Even the radial tire was invented in France (1948).

Here's a neat video of the "new" Chevy truck full-floating rear in the year 1936.

http://videos.hotrod.com/video/It-Floats-Chevrolet-Full-Floati

[DanAatTheCape]

<<If there is a passage for oil to travel from the center-section to the bearings on each end ->>>

There is not any such passage ways on these units -- and combined with the differential oil level .....

[zero]

<<If there is a passage for oil to travel from the center-section to the bearings on each end ->>>

There is not any such passage ways on these units -- and combined with the differential oil level .....

Yes there certainly is. I have no idea what you are looking at, or not looking at. The tube that connects the center housing to the bearing hubs on each end is holllow - just like a US made Dana/Spicer full-floating rear-axle assembly. Oil freely runs down it. If oil had no path - this discussion about the little oil seals that Toyota added at the end would be moot. The oil reservoir in the Toyota rear axle has a clear path to run all the way out either end (by the wheels) if not stopped by a seal. That applies to all the axles - semi-float 1/2 ton and full-float 1 ton.

With your comment . . I ask . . . just what do you think stops oil flow around the axle as it sits in that hollow tube?

[DanAatTheCape]

<<With your comment . . I ask . . . just what do you think stops oil flow around the axle as it sits in that hollow tube?>>>

I thought you were referring to other orifices besides the one at the end of the axle tube. In a regular l rear end the bearing is fully wet because it is IN the tube - in our cases, the oil has to turn & get past the hub nut. Unlike a regular rear end (which I define as having one wheel bearing), our semi floaters do not have an easy path for the oil to get to either bearing and for that oil to return to the differential.

[DanAatTheCape]

<<<Here's a diagram of the Dana 60 used in Dodge, Chevy and Ford 3/4 ton trucks. Dana 70, 70HD and 80 are set up the same and used in 1 ton and 1.5 ton trucks.>>>

If you look carefully at the diagram provided, you will note that those bearings are inline with the axle tube, not outside the tube.

Don't know if you ever have had one of these semi floaters apart - if not, or if has been a while, take a good luck at the photos in the first post on this thread, especially the first 3. I have just had mine apart - I will absolutely recommend anyone who cares to listen that they pack the 2 bearings and replace both seals if they go in there.

Academic discussions aside, I will go with the way toyota designed & shipped it. That way works good.

[zero]

<<<Here's a diagram of the Dana 60 used in Dodge, Chevy and Ford 3/4 ton trucks. Dana 70, 70HD and 80 are set up the same and used in 1 ton and 1.5 ton trucks.>>>

If you look carefully at the diagram provided, you will note that those bearings are inline with the axle tube, not outside the tube.

Don't know if you ever have had one of these semi floaters apart - if not, or if has been a while, take a good luck at the photos in the first post on this thread, especially the first 3. I have just had mine apart - I will absolutely recommend anyone who cares to listen that they pack the 2 bearings and replace both seals if they go in there.

Academic discussions aside, I will go with the way toyota designed & shipped it. That way works good.

I've had hundreds (and probably more) of full floaters apart over my 40 plus years working as a HD mechanic. I have two Toyota FFs apart in my shop right now. Regardless if Toyota/Dyna or a US Dana/Spicer - the overall design is the same.

I don't consider a discussion of design-principles as "academic." An understanding of how something works helps when trying to fix it or improve it. There have been a few statements made here on this forum about Toyota FF axles that are absolutely incorrect. Others are just a matter of opinion with no distinct "yes" or "no.". As to incorrect? Stating that there is no path of lube flow when the small seals are removed in the Toyota/Dyna axle is rediculous. There is just as much room as in a Dana/Spicer rear-axle. Another incorrect claim is . . when the small seals are removed the lube oil gets into the brakes.

I have not recommended to anyone to use, or not to use the factory equipped small seals on the Toyota/Dyna setup. Anyone is free to do what the want with their own rigs. Much of the content of these forums is about adapting and innovating and not just sticking to original designs.

I've got a 1987 Toyota box-truck with a full-floater that was used for many years with no grease-pack and those seals removed. It worked fine for the owner. I just had it apart and put seals back in.

[zero]

<<With your comment . . I ask . . . just what do you think stops oil flow around the axle as it sits in that hollow tube?>>>

I thought you were referring to other orifices besides the one at the end of the axle tube. In a regular l rear end the bearing is fully wet because it is IN the tube - in our cases, the oil has to turn & get past the hub nut. Unlike a regular rear end (which I define as having one wheel bearing), our semi floaters do not have an easy path for the oil to get to either bearing and for that oil to return to the differential.

The Toyota we're discussing are full-floaters, not semi-floaters. Toyota "semi-floaters" as used in 1/2 tons usually have sealed ball bearings - not open roller bearings. GM and some Fords use open lubed roller bearings in thier semi-floaters - e.g. the GM 10, 12, and 14 bolt rears used in 1/2 ton and some LD 3/4 ton trucks.

A "full floater" rear puts NO weight on the drive axles. They transmit torque only.

With the Toyota/Dyna full-floater - the most restrictive area for lube passasge is where the small seal is used. When removed - it gives over 1/2 a cubic inch of oil-passage space which is plenty. The bearing hubs on each end fill up with gear lube and become secondary reservoirs. That is how the unsealed FF axles work.

I'm not big on math but . . the Toyota small seal is 1.6" circle OD which is 2.06 cubic inches. The ID is 1.49" which as a circle is 1.49 cubic inches. Subtract the 1.49 from 2.06 and it comes to .57 of a cubic inch of open space for oil to flow into the bearing hubs. That is if my math is correct using Pi-R-squared for circle volume. I've looked at the space so never before felt the need to calculate it.

[Maineah]

That is one of the stupidest things Toyota ever did that is a perfect example of what ifing some thing to death. Gear oil is a far better lube then grease big trucks and even big trailers have gear oil lubed bearings they go 10's of hundreds of thousands miles before any one even looks at the bearings. I'm not going to recommend this because of the Toyota design but the first thing I did with my the hub and axle apart was to throw the little axle seal away. Yes you have to pack the bearings when it's apart otherwise they would not last a day but the gear oil soon starts to lube the bearings and washes the grease out. There is a cavity where the bearings are the gear oil lubes the bearings at the wheels rotate (provided it's not sealed out). The Toyota axle is built exactly the same as any other full flower made except for the little axle seal.

[pcmentor29]

I drove my camper up on 2x8's 2 layer thick on each side, one side at a time. Then I jacked it up from there.

That's a great idea, I have two 8 ton plastic ramps I will use next time I have to lift the motorhome. Then I will put the jack in and lift off the ramps and put my 2 ton stands in, I have 6 ton stands but I could barely lift it to fit the 2 ton stands but now this way the 6 ton stands may fit.

I swear to jack it up with my 3.5 ton jack I could only move the handle 10-12 inches at a time because of the sewer tank. I had to put all my weight on my arms at my forehead to push down.