After a successful weekend of wheeling, at the end of my 4 hour drive home, my rear axle started making some noise when decelerating, went away when i pushed in the clutch, only makes noise when off the gas and in gear. Sounds similar to a worn out wheel bearing (only thing I can compare it to) Oil was everywhere under the vehicle, looks like it came out the front seal, wondering if my vent was plugged up and then the pressure built up and blew the seal?

Anyway drained what oil was left, actually seemed like quite a bit, but it was all glittery and my drain plug was just full of metal shavings. I refilled it and took it for a drive and it still makes that same noise, sounds bad.

I've never disassembled a third member, any one have an idea on what is wrong? Do I need a new axle, should I just run it until it dies? Would putting in a spool or welding the gears eliminate the noise?

 

Pull the diff...

If its stock gears - finding a spare is easy and often quite cheap

 

you think it is just the gears?

 

I dont imagine it could be much else, if the fluid was gone, then the gears had no lubrication or cooling.

Maybe axle bearings or something.. but I'm kind of stepping into an unexplored realm for me.

 

First thing to check is the pinion bearing(outer). Grab the flange, where it's leakin', and jiggle on it side to side/up&down. If it has any wobble(play), the nut needs retightened or, at worst, the bearing needs replaced. Either/or is the likely culprit.

A little grit on the drain plug is not a huge concern. Bigger chunks that look like bits of gear tooth are another matter. If your really gonna stress about it, that can be alieved by having the ring gear backlash checked and/or adjusted(requires pulling the 3rd). The gears are probably far from gone(I like to be an optimist, sue me).

 

the bearing youre talking about would be the one where the driveshaft connects to the diff, right? since I refilled it, it hasnt leaked. There is a little output on top which I think might be the vent, and it is just capped off (previous owner did it, current owner did not notice it until now so i guess the pressure just built up until it pushed out the weakest link.

 

Your prognosis as to the cause of the leak is correct. Your also geussing right about the bearing. It should have no play, and should have a prescribed turning resistance(bearing pre-load), but don't worry so much about that now. Most important is to see if the bearing is loose, from wear or from crush-sleeve deformation. If there's not been too much bearing wear the pinion nut(differential companion flange) can be re-torqued and re-staked. It will wear your gears out WAY quicker if it's what's making that noise your hearing.

If it's fine(outer pinion bearing), then your backlash adjustment may cure that sound. At worst you'll need new ring&pinion, with an even smaller likelyhood of needing to replace the carrier bearings. But, who knows?

About the spool, you'll have the strongest possible setup with one. Wear on tires, and loss of handling characteristics are unacceptable to most if driven on hard surfaces.

 

That bearing appears to be the culprit, wobbles a lot and that is where the oil comes from.

So do I need a new seal and bearing? I have no service manual of any kind, can i just drop the driveshaft and will there be a nut there to tighten?

 

The seal, yeah it's cheap and your gonna have to monkey with the nut there anyway.

The bearing, depends on what the pre-load can be set at after you re-torque the nut. The online FSM has the correct procedure for that. Shows how to do the seal too. If another $30-$40 is in your budget get the bearing, though my experience is needle bearings are tuff stuff, and can usually be re-used/re-tightened.

http://personal.utulsa.edu/~nathan-b...35differen.pdf

4Crawlers pinion seal page.

http://www.4crawler.com/4x4/CheapTri...eal/index.html

Bear this in mind, a crush sleeve musn't be over-crushed. Meaning re-tighten in small increments checking pre-load after each one. Trying not to go to far, or you may need to replace it. Technically they are a one time deal, and you should now be replacing it before you try to retighten the bearing. But, alot of people don't(me included). Anyway if you can get the pre-load close you'll be fine. FSM tells you what max torque is before you really need to get a new sleeve, if the pre-load isn't there yet. That's also how to tell if the bearing is wore out.

 

That online FSM is awesome, anywhere I can find one for an 84? I printed out the differential section(i love free printing at my school) I'd print out the whole thing while I can if there is an FSM for my 84.

 

O.k., I haven't tried these yet. So I don't know if they work, good luck. Maybe there's an 84 somewhere, but 85 should work.

http://www.ncttora.com/fsm/index.html

 

Well I was gone for a week looking at flight schools around the country , but now I am back and tearing into the truck. Took the driveshaft off, nut was just on there, stake had lost it and it was less than finger tight, also took off this thing:


I got the oil seal out, but it still looks like this:



Is that the oil slinger and I still have to remove it ^ ?

What do I do now? How am I supposed to get that bearing out without SST 09556-30010?

Also none of the auto parts stores had the bearings or could get the bearings, any online suggestions? Should I just replace the oil seal and tighten the nut? Looks like it would be a beast to get the bearing out let alone finding one in the first place.

 

What is that thing?

and is this where the diff breather is supposed to be?


I can't wait to get it out of here:

 

So i've read a lot about a rear diff vent that goes up next to the fuel cap. Is that something I should look into even tho my truck it stock..? Sorry don't want to jack the thread but you guys seam like you know what your talking about.

 

Yeah I would follow it up from the axle, maybe even take the tube off and blow through it to make sure it is clear or you will be in my situation.

 

O.k. then.

1st pic: Companion Flange

2nd pic:That's a dirty seal (metal remnants) below which is the oil slinger, then the bearing. You can get it from http://rockauto.com/, or http://napaonline.com/.
To remove it requires unbolting the 3rd member from the axle housing(drain oil first), next disconnect the brake lines from the brake hub assemblies, then unbolt the axleshafts from the housing and pull them out(at least far enough to pull the splines out of the side gears). Then the 3rd member will be removeable.

Once you have the bearing, then you'll have to unbolt the carrier bearing cap bolts from the 3rd member and remove the carrier. With it removed all that's needed to remove the old bearing is to whack the nut end of the pinion, with something soft but heavy, it doesn't take much. The pinion will spit right out of there, so be sure to catch it. Lastly, take a punch/drift pin and knock the old bearing race out of the 3rd member. Then install new bearing and race. You can press the bearing on the pinion with the flange and the nut, or use a drift pin to tap it on slowly. Carefully put everything back the way it was, check the FSM for torque on those carrier bearing bolts, and your good to go.

3rd pic: LSPV(LoadSensingProportioningValve). Don't mess with it. Unless your having braking trouble.

4th pic:Yep, that's where that goes.

 

OK so everything came apart fine, bearing looked fine, I ordered the pinion nut, oil slinger and crush spacer from the stealership, got the seal from auto store, now I'm just going to try to figure out how to tighten and crush the sleeve to the right pressure, I guess I need something to measure the turning force? Is that just like a bar and needle torque wrench? I work at a motorcycle shop slingin parts on eBay so I'm hoping the shop has the tools I need.

 

Yeah, one that measures in-lbs. Tighten the pinion nut to 80 ft.lbs., then check the preload. It's supposed to be 5.2-8.7 in-lbs. If it isn't within that range, tighten the nut 9 ft.lbs. at a time till it is. Don't exceed 173 ft.lbs., that is the max before requiring a new crush sleeve.

 

are you just measuring the force required to free wheel the axle with the in-lbs torque wrench?

 

It's the amount of force required to rotate the pinion, it should be measured without the 3rd member installed on the truck, sorry I forgot to mention that.