rompnXJ

Ok, I'm at a loss here, maybe one of yall has some ideas i can check for.

got a '97 4.0 aw4/231 d30/8.25 with 35's and aussie lockers, stock gears. about a month ago I snapped a LF axleshaft, so I replaced it. But since then, everytime I gas it half throttle or more, ONLY when in 4LO or 4HI (4lo is worse) there is a very very loud rhythmic banging/popping sound coming from the front of the Jeep. It's about the same in Drive and Reverse. If I had to guess, I would say it's a little worse in Reverse.

here's what I've checked/tried:

replaced LF axle again
drained transfer case, inspected fluid for metal, fluid had a little water mixed in but was ok.
drained front diff, inspected fluid for contaminants & metal pieces/shavings. some slight shavings were present on the magnetic drainplug, but nothing drastic. pulled front axles again, inspected splines engagement inside hubs and inside the lockers, no damage found. marked front driveshaft slipyoke and duplicated sound and then rechecked slipyoke marks to see if it had slipped, the marks were still lined up. pulled diff cover, spun wheels to check locking/ratcheting operation, all seems ok. inspected differential carrier, case, and bearing caps for cracks/ looseness, differential case bearings & pinion bearings are intact, no excessive play in the pinion gear, the pinion gear is definitely not slipping on the ring gear, the backlash looks & feels very good/minimal.

Aussie's specification for the center gap in the d30 locker is between 3.6mm and 4.3mm, I measured mine to be at 4.1mm.

both lockers seem to be functioning properly, 4wd works properly, I have wheeled it hard every weekend since and when mudding, all 4 tires are throwing mud hard, and I have not caught the front axle doing a 1wheel peel at any time. The sound is ridiculously loud, I am running an open header and the banging/popping is louder than my engine at WOT. all 4 controls arms are tight, track bar is tight, steering is tight. Cannot make the sound in 2wd. I installed the aussie lockers myself a little over a year ago, I wheel it HARD every weekend and they have been without issue until now.

DOES ANYBODY HAVE ANY IDEAS LOL I AM LOST.
I have been trying my hardest to break whatever it is for a month now and it refuses to show itself.

ExTrEmExJ99

trans?

freegdr

Tc chain popping ?

rompnXJ

well, it definitely could be that. i didnt pull the tcase apart, i just pulled the drain & fill plugs out; through the drain hole, you can see one of the sprockets and the chain, i had it up on the lift and spun the wheels while watching the chain, the chain didnt SEEM loose, and the one sprocket i was able to see is intact.

im thinking the tcase is the only other possibility, but because this started after a broken axleshaft my gut is telling me somethings wrong with the locker

what do yall think

OleBlue

Im betting the locker teeth are messed up. Pull the halves out and look at them. Mine would still lock but it made a lot of noise from engaging and disengaging. I think my springs wore out and caused the teeth to start slipping on eachother, when that happens its ruined.

The sound it makes when it unloads is rediculously loud. pop, pop, pop, pop, pop

The reason is doesnt do it in 2wd is because theres no torque being applied.

I had to remove my rear ds to drive it home on the street because it was unbearable and unsafe to drive. When i removed the rear shaft the noise was gone and i drove home in 4wd.

Mine functioned properly to when i spun the wheels with the jeep on jack stands. Only happened when torque was applied. Aussie replaced mine because it was still under warranty.

rompnXJ

I think you might be right.. I've pulled the diff cover a few times now since hearing the noise, and looked as closely as i could at the locker teeth and they seem fine. But it looks like i need to actually pull that diff back out and disassemble the locker to really see whats goin on in there. I found out today Aussie's warranty is 2 years, so if i can remember where the hell I bought it from I should be good lol.

What caused your failure, axle breakage, fluid contamination, or just beatin the hell out of it?

OleBlue

Im not 100% sure, i did beat on it pretty good but I think it was ultimately the springs wore out and allowed the slippage, thus chewing up the teeth. It is real hard to tell there is any damage with the locker still in. In my case the very edges of almost all the teeth on both sides were rounded/obviously damaged.

The springs are something that need to be replaced every so often. I would say if u wheel it as much as u say u do, i would change them every 6-9 months. They are cheap. Maybe when the shaft broke it damaged one of the springs from the sudden unload? Hard to say.

Let us know what u find.

rompnXJ

Thanks for the input & replies everyone; it turned out to be the transfer case.

Jamie57

OK now you have us on the hook, what exactly was wrong with the transfer case?
You telling us this will help other diagnose problems of their own!

rompnXJ

I pulled it all apart today, it turns out the chain had stretched to the point where it was slipping on the front drive sprocket. The sprockets are (amazingly) not damaged, so I'm tempted to just throw another chain in it and call it a day, but I'm also looking into a wide chain kit since it's already apart.

XJmike0122

Id say beef it up if you have the money.

OleBlue

I think mine may be doing the same thing now, I cant source the sound of the loud popping/bangin i am hearing when wheeling. It doesnt always do it only 4-5 times throughout the day but sounds horrific! I am leaning toward the chain also. Im gonna tear it apart and check it out this weekend.

Did yours make any noise while driving in 2wd on the street, not loud popping but i get a loud humming while going any faster than 20 mph. I think it may be my pinion bearings but i am not sure.

rompnXJ

No noise in 2wd; what I did to narrow the noise down was this..

Jacked up the front & rear of the Jeep, pulled the rear driveshaft. Put a brake pedal depressor in place, set transfer case to 4lo, started the engine and put it in drive. Had a helper actuate the throttle (didnt take much) and then I was able to crawl under the jeep and see/hear/feel exactly where the banging/popping was coming from. It was very obviously coming from the transfer case, and every time there was a bang or a pop, the front driveshaft would stop spinning and then start spinning again.

I then pulled the front driveshaft and spun the yoke quickly by hand about a half turn back & forth, and while I was doing that, I could hear the chain slapping against the case.

Give that a shot ( at your own risk, lol...) and see what you find.

rompnXJ

Decided to pull the trigger on the widechain upgrade from JB Conversions, I'm in the middle of a full rebuild anyway, so it was a no-brainer. After comparing the parts side by side, I'd say money well spent.

From what I hear, you can get all this stuff from a np231C (s10, blazer, etc). Local junkyard would be pissed if I took apart a transfer case and only wanted the sprockets though lol.

Thanks again to yall