After replacing the pinion seal and putting the nut back where it was on my 489 diff -and filling it with gear oil that claimed friction modifier was not needed, a hum developed -does not really change pitch -but it may the rear bearings which need to be replaced, anyway.

I'm wondering if I might have messed something up as I had to remove the pinion nut with a floor jack under a breaker bar and the wheels chocked -or whether it might need the modifier.
I bought the modifier, but want to wait to use it -as I am also thinking of just getting a new third member -it's the original -45 years old -while I'm working on the axle bearings, etc.

I'd rather not have to buy the third member, so what is the likelihood I messed something up? If it's the original (160,000 miles), would it be best to just replace it anyway?
I'm tempted to just do the bearings and see what happens, but if it likely needs one, I'd rather do it all at once.

Also... if I get a new third member, will I have to have everything balanced?

Finally... where could I get a good third member that is not $1600

 

If you lift it up and turn one wheel and the other turns the same way it is a limited slip differential (LSD) and you need friction modifier, if it turns the other way, not needed.

The 489 pinion has a crush sleeve to set the pinion bearing preload. Before removal mark the nut to count the turns when removed to get it back in the same spot. The best way is to use a inch pounds torque wrench and turn the nut with axles removed and record the value, after seal replacement tighten the nut to the same spot and recheck. If the value is lower you'll need to tighten the nut and recheck until it comes up to spec (easily found with computer search).

The crush sleeve is not like shims in other differentials so retightening crush sleeve may not bring it back to exactly the same spot, if it is making noise now, DON'T DRIVE it, as you'll destroy the pinion bearings and races.

If your going to replace bearings a complete inspection should be done on all components of the differential. I hope this helps.

 

Thanks!
I am pretty certain now that the noise is coming from the right rear bearing -but will check everything while I'm there.
The axle bearing adjustment was pretty loose, so I got it to spec before driving it. I don't think I've driven the van 10 miles since I got it on the road, so I probably squeezed whatever old, dry grease was left out of it.

If we get more stimulus money, they might as well send it directly to the auto parts guy. Otherwise, I want to replace the third member, anyway -just for peace of mind -but hope to not have to do it right away.

What about balancing problems if I replace the third member?

 

No balance problems from one to another. I would rebuild what you have with a solid pinion spacer. You will need a few specialty tools but they can be bought cheap, maybe rented from parts supplier. This way if you don’t have an LSD you could purchase an Auburn, change the ratio if wanted, bearings could be ok but changing them needs a press. Many are afraid of differentials but with patience and a service manual any car guy can do it.

 

Yahhhhh -I'm gonna be using some redneck engineering as I do not have a press and don't want to lug my axles on foot (my only working practical vehicle) to the nearest (purdy far) shop.
Might have to if my idea doesn't work -or just buy a press -prolly cost about the same.

Rebuilding what I have actually sounds like fun to me -but my "shop" consists of basic tools and a driveway right now.

Need to get it driveable as quick and cheaply as possible for now due to budget concerns -but it's getting a full make-over eventually. Rear end is the last mechanical thing to tackle -then it's on to the cool factor -interior/exterior/stereo/pina colada air freshener, etc.

 

Pina Colada air freshener? Lol

 

I Agree.... Not going to fix that noise.... Hahahahahahaaha

 

Pina Colada is a nice scent -without overpowering that old car smell which I love

 

 

Welp..... I'm no expert, but I'm pretty sure those needed changing. They made a grinding noise even when turning by hand -more rust and dirt than grease.
Used a grinder to cut those off -managed to not damage the axle itself.

My PVC butter churn idea did not work -too sproingy to transfer the force, but got the new dr diff green bearings on by setting the axle upright on a piece of 4x4 so as not to damage stud threads and using the old retainer - tapping around gently so as not to touch the surface for the seal. Took a while, but not as bad as I had imagined and no damage.

 

Great, a long piece of pipe over the axle on to a large washer can bang those on and seat them properly when you hear that sound change.

 

Thanks.
I had seen the pipe idea, but was hoping to get away with wailing on the PVC because I would almost certainly scratch up the surface for the seal with the metal pipe.
If there is a way to mess something up, I usually find it.

I was dreading the job as I would have been up a creek if I could not get the new bearings on -but it hasn't been too difficult.

 

You Sir have earned yourself a non refundable, non transferable...ATTABOY!

 

 

Looks like its going to need all new bearings and seals and a good housing flushing and cleaning... Looks like it got water in it at some point in its life? Make sure the vent tube hose is good when your all done!!

 

The fact that most of the gear oil slung out before I replaced the pinion seal is going to have to suffice as a flush for now.
If I had more money it would definitely be a different story.
Things inside the third member look good and shiny-and inside the axle oil seals looks good -the outer bearings were subjected to the elements and also sat idle for a long time.
I have a vent with a little check valve -will have to make sure it is actually venting.

 

Fingers crossed...

 

Correction: the fact that much of the new gear oil drained out of the driver side oil seal while I was doing the other bearing will also have to suffice for a flush -but now I have room for the friction modifier -and a bunch more gear oil!

The driver side bearing looked quite shiny in comparison, but the green bearings look even better! The surface for the oil seal looks a bit worn, but I did what I could to make the seal ride in a different spot.....

 

Looks better from this end !!

 

I just realized the only thing keeping those green bearings in is the little clip. I better not do any donuts in my 2.5 ton vehicle.