Something bad happened in my front diff

[ReformedJeeper]

Hi Guys,

Went 4 wheeling yesterday, nothing too terribly difficult, however there was one spot that posed a bit of a challenge.I got stuck, put it in reverse. I was at about 1600 rpm, no traction, lightly sawing back and forth to see if I could get some bite, ready to give up when I heard a pop. The rear was locked, front unlocked, center locked in low range. I proceeded to stack some rocks, put it in forward and made it through. Unfortunately, I started getting a weird pop from the front diff as I continued along. At first I thought maybe the birf broke, but the sound didn't consistently occur when I locked the wheels in one direction or the other. I had someone drive as I watched the pinion flange and was able to actually see the pinion flange slip when the popping sound occurred.

In order to get home without the risk of anything seizing I dropped the front driveshaft and removed both driveflanges. In order to keep the grease in I made a plastic barrier (see photo).

Couple questions:

I have no desire to go part time, but considering this recent misadventure I'm thinking of getting some Aisin locking hubs. Obviously, if the front driveshaft is dropped and hubs unlocked this should pose no issue, however, is there any downside to running with the hubs unlocked and the front driveshaft in?

Anyone have any theories on what gave up or anything that I should pay extra attention to as I take the front end apartment?

Also, I'm on 37s with RCV chromoly shafts.

 

[inkpot]

My first guess is that you shelled a few teeth off of the ring gear. FYI, you don't really need to seal the grease in the knuckle when running without the drive plates. Just ran one from Tuscon to Phoenix at highway speeds without loosing any grease. It drove just fine and no damage to the wheel bearings. Good luck. John

 

[-Spike-]

You'd have to run with the CDL locked, but there shouldn't be any drawbacks to running hubs unlocked. Other than adding complexity to a (thankfully) simple system, and another step to engaging 4wd. I don't see any benefits, either. Have you ever gone through the diffs? Could be that you had excessive gear lash, which would put extra force on the high points of the teeth, which may have lead to failure. Take this opportunity and regear if you haven't already. If, of course, you broke the ring gear (which sounds likely).

 

[ReformedJeeper]

The rig was regeared to 4.88's by the PO before I purchased it. Although now might be a good time to get those 5.29s I always wanted.

If it was the ring gear wouldn't I expect to hear popping every revolution, not just intemittently?

Thanks for the feedback.

 

[slow95z]

i also vote ring gear. sounds exactly like what i did. yes, it will come and go. you would think you would hear it all the time but mine was random popping.

 

[Cruiserdrew]

Drain the oil and look for chunks.

There is a near certainty you broke the ring gear.

Good luck..

 

[akarilo]

Yes it's the ring gear. Been through this multiple times. Yank the diff and send it to ZUK at gearinstalls.com

Keep the 4.88's and do the Marlin t-case gears, more bang for the buck than swapping to 5.29. Also, check the carrier bolts that hold the spiders in. Mine backed out on two separate occasions, thus resulting in a blown up ring gear. Finally spot welded the bolt heads this last time. No issues to speak of now.

 

[ReformedJeeper]

@akarilo, I've already got the Marlin t case gears. Also, I'm not to familiar with the diff components, I'm assuming you are referring to the carrier bolts in the 3rd member correct? Also, do you have any pics of your spot weld?

Thanks

 

[akarilo]

 

[ReformedJeeper]

So here is what the drain plug looked like

Didn't see any really big chunks of metal come out with the diff fluid, although the drain plug had quite a bit of metal on it.

 

[cjmoon]

Somthing not happy in that diff. Reverse is the weekest point in diff gears. There designed for the most strength.

Why wasn't the front locked? Having it jump around could put more stress by loading and unloading as the different tires catch rapidly. Kind of like bouncing a leaf sprung rig.

 

[ReformedJeeper]

So I didn't lock the front because I felt that would be more stressful on the axle (obviously wrong here). Secondly, as the axle locks turning becomes difficult, and I wanted the maneuverability. In retrospect, knowing now that the front ring gear has significantly reduced strength in reverse, I would do a lot of things differently. Ultimately, it was a case of bad driving.

Oh well, live and learn.

 

[ReformedJeeper]

Thanks for everyone who chimed in, your help was appreciated. It's definitely the ring gear.... I'll either take it to Yotamasters or send it to Zuk. Anyone have any feedback on yotamasters on 80 series gears? They are local to me so its easier than packing it up and shipping it

 

[-Spike-]

No, but I had Zuk do mine, he is a gear god. Frankly, I'd go over both diffs- and a good reason to do the 5.29's, if that's what you really want. I love them, but I don't think I could handle the t-case gears on top of them. My speed is pretty much tied to my RPM's in low range- 2000 mph = 20mph, 3000 RPM = 30mph, etc. You'd be at like 25% less than that (or whatever the reduction is). On the bright side, you're already at 4.88, not much difference, but when you have to switch to high range for smoother trails at least you'll be lower than you are now in high.

 

[-Spike-]

Also, if you had locked the front, a lot more people would be yelling at you for that.