I followed through on my plan to modify the stock side gear and also added a slight bevel to the front third of the c-clip. I used a straight die grinder with a conical stone for the side gear and a 12" circular sanding machine to bevel the c-clip. What I like about this was that the c-clip will still present its original full width to the groove in the axle shaft when it is seated, but the bevel also allowed the side gear to be clearanced less, preserving as much integrity as possible. It will be a little tricky getting the clip back out, but I tried it a few times before I committed to sealing everything back up again and it does come out if properly aligned. As a temporary measure, it is fine.
As I was hoping, all of the noise and concussive nonsense has abated. I think I have definitively shown that the problems I was having were being caused by the locker malfunctioning. It's annoying that it took me several months to reach this simple conclusion, but there were several points where my effort could have been applied more efficiently.
Now that I've determined the source of the symptoms, I'm wondering what caused the problem. Was it just that I wheeled it too roughly with all that winter wonderland wheelspin, or were there other mitigating factors? Various pieces of evidence have surfaced during the course of this inquiry. First, the Aussie's center gap was correct and just about right in the middle of the acceptable range when I measured it the first time I pulled the diff cover. Externally, the locker looked fine. It was a mistake to not disassemble the locker at that point and examine the geared faces of the components that are actually responsible for the locking/unlocking.
Because I didn't examine the locker carefully, I looked for other areas that might cause similar symptoms. I became convinced that the transfer case chain was slipping. I replaced it, but noticed as I did that the new chain was very close in size to size to the old one. Once I got everything back together I still had the same problems when I did the test drive.
I had also eliminated the drive shafts as the source of the symptoms. When I ruled these out, the rear axle was the only part of the system left that was likely to be acting like a, well, malfunctioning locker. I had planned to swap the stock open differential spider gears just as mtbxj87 had astutely suggested way early on in this investigation, and cleverly sourced them from my stock '99, which I then installed my extra locker, a Powertrax No-Slip, in. The No-Slip has been working great with the smallish 235/75-15 tires on the stock Jeep. I think it will last a long time in there and I don't regret not using it for the '98, even if it would have allowed me to diagnose the Aussie a lot sooner.
Anyway, another piece of evidence that seemed noteworthy was that, as the pictures show, one half of the locker looked to be in much worse condition than the other. Then I found that I couldn't install the c-clip on the driver side axle shaft because the shaft wouldn't insert far enough into the differential case to fully expose the groove. Please consider the following thread, in which center gap in the similar Lockrite locker is briefly discussed:
http://www.naxja.org/forum/showthread.php?t=1079767
The key piece of information that stood out for me there was the point that the center gap itself is not the dimension that matters, but rather the distance from the center pin to the locker half. The center gap is a surrogate measurement that assumes the sum of the left and right gap values are approximately equal. While it is important to note that the function tests were all satisfied, it is almost certain that the actual distance from one half to the center was substantially different than from the other half to the center. Perhaps this hastened the locker's demise.
I have not yet determined if the outer axle bearing was completely seated, but I think it probably is. I have a suspicion that the differential case itself is somehow implicated in this mess. When I bought the Jeep, it had a Dana 35 sitting under it. I found someone selling a set of axles here on
with 4.10 gears and the rear was a 27 spline Chrysler 8.25. The 8.25 had c-clips that came out easily and I believe that indicates the outer axle bearings were seated correctly. The fact that the c-clip won't install on a stock side gear in the replacement 29 spline case in the same housing seems to point to the case. I also bought the case from someone else on
. I'm not making any accusations, but I wonder if that individual had any problems with it before deciding to sell it. Because I now have a set of spider gears installed in the case, and they seem to fit in and mesh correctly, I have to assume that when this case was manufactured, it was machined to correctly align the spider gears, i.e. it's not that one of the seating surfaces for the side gears isn't the right distance from the center, it's that the center pin holes were bored a little too far towards the passenger side. This is just speculation at this point. When I tear it apart again, I think I need to measure the gap between the side gears and the center pin. I should have done that with the locker side gears also but I wasn't thinking clearly enough about the case geometry at the time. Now that it's sealed back up, filled with oil, and rather inconvenient to take the measurement, of course I see it more clearly.
This is encouraging, though, because it makes me believe that if I get an OX locker for this axle, there's a good chance that it will go in fine and that I may not have any issue with the c-clips at all. Or, I could go the cheap route and get another lunchbox locker that will suffer the same demise. The cheap route is clearly less desirable in the long term, but I've had a Ford 8.8 sitting in the garage for a while. This is the axle that I'd ultimately like to be running. But it needs to be regeared. And if I'm going to regear it, I'm going to go lower. That means I need to go lower in the front axle as well. And the 8.8 axle needs to be prepped to go under the Cherokee.
I think the answer is clear. I will get another lunchbox locker for the 8.25 for the time being. I will get the gears and install kits for the 8.8 and the Dana 30 next. Later I will get an OX for the 8.8, probably after I wear the Aussie out that I have for it. I have almost everything else I need for the 8.8, including an open differential case so,I can use the Aussie. Even so, I don't have a lot of free time so this will push off the 8.8 project for a while. In the meantime, I'll just continue to enjoy my Cherokee as I have in the past. I want the OX, but I really don't want it for this particular axle. So thank you all for helping me to figure this out. I was hoping for a little more input from the XJ Titans here, but I've still arrived where I needed to, and hopefully this dissertation will help someone else out when their junk starts falling apart. I can't stress enough that my initial inspection of the locker was wholly inadequate. I found the best way to get the pins out was to use a set of forceps with fat finger grip areas that thinned out just in the last ~1 cm, allowing them to get I to the tight space to grip the pins. The pins like to not come back out of the holes they are set in because the viscous oil makes for the development of a partial vacuum behind the pins. Even so, the method of pulling the pins out a little, then a little more, then a little more and so on until they were out worked.
I know that I tend to write a lot, but I think best this way. Hopefully it has been worth the read. I will post up again after I get the new locker because I want to record the side gear to center pin dimensions, which will help me to think more about why I had to modify the side gear and c-clip to get the clip in and test the theory that the locker was, in fact, at fault. Until then. . .
