D44 Front Axle Problem - Should I Worry?

[Russ Chung]

Just before I left for the Arizona Strip (see the trail report in another section of this forum) I changed the fluid in both differentials. I drove about 3,000 miles on the trip (about 800 miles on dirt). When I got home, I noticed that diff fluid was leaking out the passenger side of my front D44 axle. I have never removed a differential before, so I read up on the procedure, bought the replacement seals, borrowed a case spreader and set to work.

When I drained the fluid, I discovered that it was milky white. This was the first time since I bought the Jeep that the drained fluid was not clear (this is about the 30th time I've changed the fluid in the diffs). Although I was surprised that the fluid was contaminated, that didn't worry me because it had only been a few weeks and a relatively few miles since the last fluid change. What does worry me is that when I went to remove the differential, it came right out; THERE WAS NO PRE-LOAD on the carrier bearings!! I had expected to have a hard time pulling the carrier. I had borrowed a case spreader, bought a dial indicator so that I wouldn't spread the case too much, got ready to hook up the case spreader, and when I removed the carrier bearing bolts, the carrier practically fell out! I was able to lift the carrier out with my hands without any pry bar and without using the case spreader. There is one shim on each side. The shim on the driver side measures .130”. The shim on the passenger side measures .139”. The service manual says to add .010” to the zero end play measurement to properly pre-load the differential bearings but obviously there was no pre-load on the bearings. The wear pattern on the gears appears to be OK. Here are pictures of the gears.





This was a used D44. I replaced my original D30 axle with this axle about 80,000 miles ago, and I don't know the previous history of this axle. My Jeep is my daily driver, so I have to put everything back together the way it is and deal with the pre-load problem later. I’m afraid that if I start messing with the shims I’ll mess up the gear contact pattern. I don’t have any immediate plans to go anywhere that would require 4WD. Am I OK as long as I don’t use 4WD or should I drop everything and take it straight to a mechanic who can set up the shims properly?

[RAT]

Russ,
If you add the .010 to get the preload you need to split it 50/50 or you will change the clearances. Shims come in .005 increments. I think I have a few of them. One on each side and your golden. Did you check your axle vent to make sure it isn't broken? That may be where the water came from that boogered up your oil. I doubt if the seal leaked water past unless it is torn really bad.

[randysjeep]

There was probably a preload on your bearings whend the diff was new. The bearings and races are probably worn. My suggestion is to replace carrier bearings and races, and reuse old shims exactly how they were. You will find that your preload is back and your contact pattern is back to what it's supposed to be. Speaking from experience with my d60.

[RAT]

There was probably a preload on your bearings whend the diff was new. The bearings and races are probably worn. My suggestion is to replace carrier bearings and races, and reuse old shims exactly how they were. You will find that your preload is back and your contact pattern is back to what it's supposed to be. Speaking from experience with my d60.

Possibly, but if the bearings had gone so bad that the preload went away like that there would be other things going on in there as well. Like worn teeth, noise under driving conditions, metal in the oil, etc. I think Russ dodged a bullet for 80,000 miles. Lucky SOB...

[randysjeep]

On my d60 I could see the wear on races. The original reason I pulled the carrier was to replace o-ring on arb. It came out easily. I replaced bearings, races and the o-ring. I was alot harder to get back in. r+p were fine, never heard any noise. Only giveaway was o-ring failure. Also after inspecting the arb I had notice that the carrier was running off center (not L - R, forward toward pinion), causing surfaces to rub metal to metal at o-ring groove. This was with about 20,000 on axle, not a daily driver.
So anyways... this may or may not be the case with your diff.

[aw12345]

If it ran quiet and the bearing races did not spin in the diff housing, I would put it back together without much of a worry.
Quite a few Dana carriers come out easy. The thing is if it worked ok before you took it apart, what makes you think it will not, after you put it back together?

[RAT]

I went by yesterday and dropped off some shims. The parts all look good, showing only a little wear and some corrosion from water that got in the diff. I don't think Russ will have any issues with the axle after he reassembles it. Apparently one of the shaft seals was in the bore cockeyed and wore out enough to let water in. Oily milk shake, mmm, mmm good...

[Russ Chung]

My first thought was to agree with Art. I've had the axle for 80,000 miles, and the wear pattern on the gears and on the bearings look great, so if it ain't broke, why fix it? But the shop manual clearly says to take up the slack and then add an additional .010" to pre-load the bearings. So I used the shims that Kurt was kind enough to deliver. After I took up the slack I added an additional .003" to each side, so the pre-load is more than zero but less than the amount specified in the service manual. My theory is that the lack of pre-load may be due to a weakened housing which may have been caused by damage to the housing either by myself or by the previous owner of the axle. The lack of a preload caused the axle seal to work loose and caused the leakage. The reason I suspect that the seal worked loose is that the sealing surface looked good but instead of being round, it was slightly elongated, and the surface of the housing in which it was seated was corroded. These facts lead me to suspect that the seal was not completely seated in the housing.

After I reassembled everything, I test drove it. There was no noise or vibration, and when I got back home, I touched the diff housing and it was warm but not hot. I drove it some more today and still no leaks. Time will tell if I did the right thing.

[6spdYJ]

Glad you got it fixed. If you still don't feel right about it, I'm sure there's lots of guys who would be willing to trade you for a proven-good D30

[RAT]

It looks like the axle is working fine. I found a case spreader on my front porch this afternoon, so I take it Russ came by and dropped it off.