More rear Dana 44 questions?

[Jeffsj]

I know I have posted more than my share of threads lately, but I have a few more questions I'm hoping to get some answers to:

The first is about the axle bearing races. Is it normal that the races are loose enough in the axle tube that I can pull them out by hand? They are a tight fit, but not a pressed fit.

Second is, why are the rear axle tubes filled with gear oil, but the fronts are not? I originally thought it was to lube the wheel bearings, but there is a seal to keep the gear oil off the bearings. Is it just to add to the oil capacity?

The final question (for now) is, is there a good way to pack the wheel bearings while they are still on the axle shaft? The inner seals were leaking and the gear oil washed the grease out of them. They still look fine, so I just want to re-use them. Thanks for any answers you can give me.

[REDONE]

Well, you got some seriously goofy stuff going on. The rear wheel bearing races are not a press fit, just imagine trying to pull them out if they were! That'd be another $50 single use tool from Harbor freight for yuh. They should be snug though.

The axle tubes shouldn't be full of grease. It's not uncommon to grease the axle shaft so it slides through that inner wheel seal and into the diff nicely, but the tubes shouldn't be "full" of grease.

You definitely should NOT press the bearings off to pack them, they are easy enough to pack on the shaft. I use a needle attachement on my grease gun and inject the grease inbetween the rollers from the norrow end of the bearing cone. inject grease until it comes out the wide end AND through the cage at the rollers then move to the next roller. It's actually clearner and quicker than scooping up two fingers worth and trying to press it in manually.

Now some extra good info for you, in the later years Dana yanked the inner wheel seals, and so should you. Packing wheel bearings is an annual maintenance item, bi-annual if you tow or carry heavy loads, but ONLY if you have the inner seal. They made no design changes (well, one, kinda, sometimes), no difference in part numbers for the rest of the parts or nothin. They just yanked the inner seals. If you use gear oil to lube the wheel bearings you only have to pack the bearings when you install an axleshaft. The oil will eventually wash the grease out and then oil will lube bearings from then on out. Changing diff fluid counts as your wheel bearing maintenance too. You DO still have to pack them when you install them to protect them as they wear in and to keep them lubed until the gear oil can reach them.

If you yank the inner seals, I do recommend one other part change. Use a front D44 cover (or just about any aluminum cover). If you look at your front and rear diff covers side by side, you will notice two striking differences. The front cover is about twice as thick, but much more importantly, the fill hole is higher. Since you're now using gear oil to lube wheel bearings too, you want the fluid level closer to the height of the bottom of the tubes and you want more oil period.

[rocklaurence]

You'll also notice a bulge at the end of the axle where the bearings reside. The bulge holds a pool of oil to lube the bearings. So, dont sweat packing the bearings. Just make sure the oil level is correct.

[csuengr]

The race usually comes out with the bearing. Some times it doesn't. On D44 in the rear of my CJ (from a 88' GW), the race comes attached to the bearing. This axle also doesn't have a seal to keep gear oil away from the bearings, but uses gear oil to lube them. The axle seal is outside the bearings.

Your front axle has it's axle seals on the inside of the diff housing. That is why there is no oil in the tubes. There shouldn't be any oil in the front axle tubes. On the rear, they just let the oil slosh around in the tubes.

[TUDrewser]

So, I assumed all axles needed bearings done...when did they start removing the inner seals? Would my 90 GW have bearings lubed by diff oil? Front and back?

[FSJunkie]

When I had mine apart it had tapered roller bearings pressed on to the axle and the race pressed into the axle tube. I don't think there were inner seals. This is a 1972 axle. The bearings were the originals with 140,000 miles and had never been packed, as the manual says they are lifetime lubed and never need repacked. There was some grease left on them, but it had been watered down with nasty gear oil. They were also extremely dirty, so it looks like gear oil gets in there, but doesn't do a good job of flushing and replacing itself.

I looked into replacing the bearings and all the replacement bearings were unit roller bearings, with rollers parallel to the axle shaft and the outer race built on. Rather than try this later design, I simply repacked my old bearings, which were in decent shape still, and reinstalled them.

How is the bearing preload adjusted on these? Are there shim packs pressed onto the axle shaft under the bearing?

[REDONE]

Nope. The preload is applied by compressing the seal with the backing plate. They don't have a ton of preload.

For FSJs I believe they stopped using the inner seal around 86. You can't fill that cavity at the end of the axle tube with oil on installation, so pack the bearing for install.

The "lifetime lube" bearings are an available option but they are not tapered roller bearings, they're ball bearings, have a bad rep and the warranty is useless considering the cost of the bearing is nothing compared to the labor of installing it.

[Jeffsj]

Thanks for the responses guys! Unfortunately I'm still a bit confused. It seems most people are saying the bearings are lubed by the gear oil, but how does it get past the oil seal that resides right in front of the bearing? I understand they eliminated this seal in later years, but I'm afraid to leave it out, because I am not replacing the bearings, so I am reusing the outer seals and don't know how they would handle being the sole seal for the axle.

[whsii]

Well, this is an ongoing debate.

Most people here are agreeing that the bearings need to be lubed.

The inner grease seal was installed to keep deep water crossings from contaminating the gear lube.

Some people on the boards say to remove the inner seal and run with it. This is the standard for most vehicles of the era. (no inner seal) If you have an inner grease seal, and do not see it, and do not grease the bearings, you will have a failure in around 5K.

If not using the inner grease seal, the cover that has the fill plug higher is great! I have not heard of it until the above post.

Regardless, With a Dana 44 or an AMC 20, I would pack the bearings with axle grease. Knowing 90 weight gear grease would lube it, I would pack the bearings...

Just my thoughts.

[FSJunkie]

Grease them no matter what you have.

Gear oil will soften up and dissolve the grease into a paste anyway.

[REDONE]

Thanks for the responses guys! Unfortunately I'm still a bit confused. It seems most people are saying the bearings are lubed by the gear oil, but how does it get past the oil seal that resides right in front of the bearing? I understand they eliminated this seal in later years, but I'm afraid to leave it out, because I am not replacing the bearings, so I am reusing the outer seals and don't know how they would handle being the sole seal for the axle.

Don't worry, you're not the one who's confused. The way your axle came from the factory, the bearings were NOT lubed by the differentials gear oil. The inner oil seals ONLY purpose was to separate the gear oil from the bearing grease. The Jeep engineers felt that this was a superior way of doing things when everyone else let the oil and grease mix. Ultimately it was found to be superfluous at best and detrimental at worst so they conceded and took that inner seal out. whsii is absolutely right, a compromised inner seal allows enough gear oil in to compromise the bearing grease without effectively lubricating the bearings and they will fail.

In your situation I would try like heck to buy new bearings and seals, even if they were chinese roodi-poo from oreillys. (big shocker for you, Timken USA is a brand name, not the country of origin anymore. They're selling Chinese roodi-poo too, the last set of SKF i bought were from mehico, and to the best of my knowledge Koyo is still very proud to be JDM [Japan Domestic Manf], I buy USA when I can but have pretty much given up with bearings). There's no shame in buying what you can afford. If you stick to your plan it doesn't make you a fool and I'll be the last one on the internet to start calling you names, but I think of finding an inner oil seal and gear oil in what seems like a still-good bearing as the starting gun in a race to bearing failure.

Just for reference from my posts above, a side by side of stock covers:


And I know some folks have probably never seen one of these. I think it was about $3 at Pepboys:


This one is just because I'm awesome:

[Jeffsj]

Redone, I think I'm gonna take your advice and get new bearings. Should I just leave out the inner seal? Would I need a different outer seal, or is the original sufficient to seal in the gear oil? Thanks for all your thoughts everyone. It's very appreciated.

[REDONE]

new seals too. right now Vatozone is half the price of the rest. Most want $25, the 'zone is $12.

Most common p/n is 9912.

EDIT>>>I do not recommend inner seals. If it goes bad it will take out your wheel bearing. Seriously, if you knick it just a little bit when you slide your axle shaft through it you'll be doing this whole thing over again in 3 months. That's assuming you catch it when it's still just a bad bearing. If you drive with your windows up (winters coming) you might not hear it squealing until it's already so hot it spits your axle shaft. I've done it, Flints done it, Carnuck hasn't done it that I know of, but it happened to his Honcho while I was behind it. It costs money and provides no benefit. I believe it's a carry over from the days of 2-piece axle shafts and the engineers both at Jeep and at Dana treated it with a "because we've always done it" perspective, but that's just my own guessing. AMGeneral would be far more likely to know why they kept the inner seal so long than I.

[REDONE]

Second is, why are the rear axle tubes filled with gear oil, but the fronts are not?

The old site usta have tags that listed when the post was last edited!

I'm not the engineer that designed it so I can't tell you "why", but I can tell you that the front is vented on the diff so it's ok that the seals are in the pumpkin. The rear is vented on the tube, so even if you have the bores for seals in that pumpkin, don't use them.

[carnuck]

I do Set 10 (Timken) bearings on my rear axle (one piece) and they are caged rollers (not tapered or ball bearing) and I put in synthetic grease. So far, none have gone again on me. I swapped to J20 rear and Ford 3/4 ton front axle with J20 knuckles so I shouldn't have an issue.

[whsii]

Sorry Redone,

I respect your opinion Sir!

If I were driving only on asphalt, I would follow you and not use an inner seal.

Taking it off road, fording creeks and mud, etc, I would rather have the bearing packed with grease as designed and do periodic maintenance repacking the bearings instead of flushing and re lubing the hole rear end.

My "prissy" jeep, when finished, will be driven and go off road.

Just my thoughts my friend...