Vid

Hey all. Sorry to say, but I have some truly basic questions about the rear end on my Jeep - 2007 Jeep Wrangler X with a Dana 44 rear axle. Stock everything, no mods, 198,000 miles. Daily driver, work horse, country road pioneer, heavy hauler, 4WD low on the farm, all around amazing lady. The transmission is a rebuild that's only got about 30K on it, replaced the shifter assembly then as well. I've been keeping this jeep running as best I can since 2007. I do 100% of my own work on her in my gravel driveway because every time I take her to a "professional" shop they literally just mess something else up. I've done a lot of work on this vehicle in the last decade including, complete brake jobs/parking brake rebuild, steering component replacement, full suspension overhaul, countless electrical repairs, sensors, pinion seals and drive shaft rebuild, you name it... and still, I don't know everything. It is now time to learn everything I can about rear end rebuilds. I am easily confused and know just enough about working on cars to be potentially very dangerous, and therefore am looking for some yes or no answers and some straightforward advice before I ruin my beloved Bobbi's rear end. Thanks in advance for any help y'all can offer.

1. There are both an outer axle seal at the wheel bearing and an inner axle seal at the differential housing? Yes, or No.

2. If both seals are good, there shouldn't be any fluid in the actual axle housing other than in the pumpkin? Yes, or No.
2.2 Is there a difference between "axle fluid" and "differential gear oil"?
2.3 Whats the correct diff oil for my jeep?

3. If I have a leak at the outer axle seal (at the wheel bearing), does that mean that the inner seal is also definitely leaking?

4. If I replace the wheel bearing and outer seal, do I care if the inner is leaking or does it need to be done?

5. If I replace the inner seals at the diff, should I replace all the differential bearings or am I just being nuts at that point?

6. I have in hand Spicer replacement bearings with seals, lock rings, and mounting plates. Says they're compatible online, but the new bearings are factory sealed and look to have a flat alignment, vs the old ones that seem to have a slightly conical layout and removable outer races (or maybe they weren't like that before I pulled the axles?). I'm so confused as to whether they're just a different style and are fine, or if they won't work and I'll just be wasting my time putting them on my axles. Will attach pics of old vs new. Any advice appreciated.

For more context, I already pulled the rear axles and opened up the differential housing for inspection. I am amazed at how beautiful and clean everything is in there at 198K. Found just barely a trace of metal filings on the diff drain plug and no rust in evidence anywhere. There is no play in any of the moving parts in the differential assembly and none of the teeth seem to be worn unevenly in any way. What I really want to do is just replace my wheel bearings, refill the diff and move on, but if the inner seals are leaking and that will just wreck something later, I will obviously take this as far as is needed because Toyota can pry this nearly immortal jeep from my cold dead hands!


old bearing on axle (outer race closed)

old bearing on axle (outer race removed)

new bearings

DanB13JKU

Unless Jeep did something really weird on the JK D44, there is no inner seal. The bearings are lubricated by the gear lube (75W90 or 80W90, have also seen 75W140 synthetic mentioned - don’t have my owner’s manual handy to check). I recently found out that the early YJs had no C-clips and the bearings had to be packed, so I wouldn’t be surprised if there were variations throughout the years…

The bearing on the axle shaft definitely appears to be tapered, strange that the “compatible” replacement would be of a different design.

Here is a diagram from an online Jeep parts supplier showing the shaft with only an outer seal. I’ll also include a screenshot of what they show for the bearings, you may be able to cross-reference the part numbers to see if you were given the correct pieces.

Vid

Thanks so much for the info. The diagram and parts pics are very helpful. Those product photos definitely look like what I have, which makes me feel a lot better about installing them.
It makes sense that if the gear oil is what lubes the bearings there is only an outer seal so the oil can move around between the diff and the bearing. I am starting to think I've confused what's going on in the rear with whats going on in the front differential. If you know, does the front differential have inner seals? I'm only thinking that because the front rotor bearings are sealed (aren't they?).
Tanks again for your reply!

DanB13JKU

The front does have inner seals. If it’s the same as the D30 in the TJs you must remove the differential and press them in from the housing ends. Haven’t looked at the JK closely yet, but my TJ also had a plastic shield at the outer end of the shaft. It wasn’t a seal, probably more to keep dirt and debris out of the tubes.

resharp001

That is all correct. The front is just inner seals and the rear is only outer seals. Yes, gear oil is the same as "axle fluid". If you have a limited slip diff you'd want to make sure to use a gear oil with additive, but tbh, just throw a good synthetic in there regardless.

I've bought a lot of bearings.....that price seems absurd!



You can get brand new chromoly axle shafts with bearings and seals pressed on, plug and play, from Northridge4x4 for $370. How could those rear bearings cost so much alone? -

Vid

Hey all! First of all just wanted to thank everyone again for helping me with their knowledge! I ended up getting the bearings swapped on the pulled axles at my local shop after doing an extensive differential cleaning and inspection. The diff still looked good as new and with the axles back in everything is working just fine, so that was happy news. Unfortunately I've run into a problem... After installing the axles with the new bearings, I had my rear passenger brake caliper lock up. Ordered new calipers, got them changed out with no trouble at all, only to find that my rear passenger bearing is leaking ever so slightly. Any chance they're related? If not, anyone have this experience after changing them out? Any trouble shooting tips? Beyond all that, after rechecking the torque on the bearing seal bolts I did find that the two lower nuts were a little below what they should be. I tightened them up and the jeep drove just fine for a 6 hour round trip through the mountain of WV, but there is still just a tiny lil drip of gear oil coming out behind the brake shield. I checked the fluid level at the diff and it's still sitting just at full so I'm not loosing that much, but its still very concerning. Any advice would be appreciated.

resharp001

So when the shop swapped bearings, i have to assume they installed new seals as well right?

Vid

Yes. I got the axles back with the new bearings pressed on and they definitely put the new seals on there.

resharp001

for whatever reason, you're not getting a good seal right there. it's not going to be detrimental, but that is gonna be a pain in the ass for a long time considering you just did it. the only real solution IMO is pull it back out, make sure things are very clean and not a spec of debris or anything, and there is a possibility you'd have to replace that seal again.......or live with it.

There's no chance that the bolts on the back of the retaining plate are spinning as you turn the nut right, creating a situation you can't get it torqued to spec? Those will tend to spin from time to time.

Vid

Bolts are not spinning that I can tell. When I went back to double check the torque on the nuts, I was definitely able to see more threads when I was done on those bottom two and they were a close match to the top two, so at least I'm pretty sure that's not whats going on.
As for the rest, I was pretty sure I'd have to pull it all again and get a better look at whats going on. Was just hoping someone would tell me otherwise

Thanks as always for the advice!