Reman rear diff questions/suggestions

[shane10]

Hi all, have had the all too common rear diff whine for severals thousands of miles now, never bothered me that much. I have noticed recently a pretty significant amount of metal on the magnet, much more than usual, along with the whine getting worse, and occasionally roaring at speeds 65+ MPH. I have also had a slight leak at the rear axle seals that has developed to drips on the garage floor, which brings me to my next question.
Obviously I will need to be replacing the rear seals in the near future, and I assume will need to replace some components of the rear diff as well, whether it's ring/pinion, carrier bearings or something else I have no idea. Rather than taking the diff apart and diving into something I have very little experience with, I was thinking of just replacing the entire diff with a reman zumbrota, RAA440-1384B | Zumbrota Drivetrain.
Does anyone have any experience with the company/products? Are they reliable? It does look like they offer a 2 year warranty which is very promising. Would be about 1k flat after shipping both ways (core return).
Although the more expensive route I feel it's my best option to avoid the headache of a partial/full rebuild. Any thoughts on this?
2002 XLS 215,x.. miles, diff is open 3.55 8.8 Axle code 45
Thanks in advance

 

[imp]

Hi all, have had the all too common rear diff whine for severals thousands of miles now, never bothered me that much. I have noticed recently a pretty significant amount of metal on the magnet, much more than usual, along with the whine getting worse, and occasionally roaring at speeds 65+ MPH. I have also had a slight leak at the rear axle seals that has developed to drips on the garage floor, which brings me to my next question.
Obviously I will need to be replacing the rear seals in the near future, and I assume will need to replace some components of the rear diff as well, whether it's ring/pinion, carrier bearings or something else I have no idea. Rather than taking the diff apart and diving into something I have very little experience with, I was thinking of just replacing the entire diff with a reman zumbrota, RAA440-1384B | Zumbrota Drivetrain.
Does anyone have any experience with the company/products? Are they reliable? It does look like they offer a 2 year warranty which is very promising. Would be about 1k flat after shipping both ways (core return).
Although the more expensive route I feel it's my best option to avoid the headache of a partial/full rebuild. Any thoughts on this?
2002 XLS 215,x.. miles, diff is open 3.55 8.8 Axle code 45
Thanks in advance

@shane10

As with any relatively obscure seller on the net, there is risk. Your description of the noise as well as metal build-up suggests, in my experience, the possibility of gear misalignment from age and wear. Such condition can often be "felt" with a fingertip on the top edges of the ring gear drive side of it's teeth as a sharp, almost razor-edge. If present, it can often be remedied without gear replacement by replacing the pinion gear bearings and differential carrier bearings, and re-aligning tooth contact pattern. Whine is rarely encountered with bad differential bearings, they "chuckle" or rattle when driving in other than a straight line.

Just my thinking to save some dough. A good "gear-head" can easily replace bearings effectively if he has acquired hypoid-gear understanding. Couple hundred bucks at most for parts. A purchased rebuilt is OK if results prove so.........imp

 

[shane10]

@shane10

Just my thinking to save some dough. A good "gear-head" can easily replace bearings effectively if he has acquired hypoid-gear understanding. Couple hundred bucks at most for parts. A purchased rebuilt is OK if results prove so.........imp

After seeing you respond to so many threads regarding this topic I was hoping I'd be hearing from you, always solid advice. If your assumption is right in the problem lying in pinion gear and carrier bearings, is that in itself a concern for catastrophic failure? Or is there no way to tell without inspecting it. I changed the gear oil about 10k miles ago, and have checked the magnet twice, both times it was totally covered.
The noise is most audible when on the gas, and is very noticeably quieter when I take my foot off if that narrows it down any.

I like to do all work on the truck myself, but am not entirely confident working with internals of the diff, nor do I really have time at the moment. Sounds like from most other posts shops charge $6-700+ for this job, assuming nothing else needs replacing as well. In that case I don't mind spending the few extra hundred to have a fully rebuilt diff I can swap myself in a day and hope the quality is good.

I guess my main concern is immediate reliability, I have a 2500 mile trip coming up and would hate for the diff to grenade on the way out, in your opinion is this even a remotely likely scenario with these trucks?
Thanks again

 

[imp]

After seeing you respond to so many threads regarding this topic I was hoping I'd be hearing from you, always solid advice.

If your assumption is right in the problem lying in pinion gear and carrier bearings, is that in itself a concern for catastrophic failure? Or is there no way to tell without inspecting it. I changed the gear oil about 10k miles ago, and have checked the magnet twice,

both times it was totally covered.

The noise is most audible when on the gas, and is very noticeably quieter when I take my foot off if that narrows it down any.

I like to do all work on the truck myself, but am not entirely confident working with internals of the diff, nor do I really have time at the moment. Sounds like from most other posts shops charge $6-700+ for this job, assuming nothing else needs replacing as well. In that case I don't mind spending the few extra hundred to have a fully rebuilt diff I can swap myself in a day and

hope the quality is good.

I guess my main concern is immediate reliability, I have a 2500 mile trip coming up and would hate for the diff to grenade on the way out,

in your opinion is this even a remotely likely scenario with these trucks?

Thanks again

@shane10

See Above. (Your enthusiasm for my background is contagious!) Not an assumption, understand, just a pick of several choices evident having begun working intensively on drive axles many years ago. Without visual inspection, it's still guesswork. Continued metal deposited on a magnet is bad news, of course. If it's grayish mushy stuff without any hint of shavings or chips, that's better than the latter. Noise prevalent "on the gas" means under load, almost certainly generated by the gear teeth, but originally caused beyond doubt by misalignment from bearing deterioration. Early pinion bearing noise is high-pitched compared to ring gear bearings, as pinion spins several times faster than the ring gear and axles (3.55 times, etc.). Ring gear noise almost always increases under load, early-on disappearing when coasting, off the gas. Late-stage will show noise constantly: it is then IMPERATIVE to go into it.

There is incredible strength inherent in a driving gear-set's structure. Think of tightening a bolt to 100 ft-lbs as you probably have done, really tugging on that torque wrench. Consider an engine developing 300 ft-lbs: in first gear @ perhaps 3 to 1 gear ratio, the pinion bearing is transmitting 900 ft-lbs to the ring gear, which in turn is hitting up the axles with 900 X 3.55, way over 3000 ft-lbs! This is how I get "gut-feel" for what's going on.

Be aware there is a reason why a used center section is for sale: BEST, it came out of a low-mileage wreck. Worst, it, too, is no damned good. Usually, bone yards guarantee against leaks, cracks, noise, but that's little consolation for the guy who installs it and then must rip it out again.

Regarding your trip: A more educated guess on my part would necessitate actually witnessing the offending condition, and even then I have been wrong in the past often enough to be wary. I would hate to mislead you, and be remiss if I did so. How much driving will you do before the trip? Base noise results during that time on your decision to do it. Spearing "dinner" in a barrel of water often satisfies hunger. I hope we win this one! Good luck! imp

 

[MrPulldown]

Looks like used ebay units are pretty cheap. You could rebuild/partial on the bench top and drop it in when ready.

 

[shane10]

@shane10

See Above. (Your enthusiasm for my background is contagious!) Not an assumption, understand, just a pick of several choices evident having begun working intensively on drive axles many years ago. Without visual inspection, it's still guesswork. Continued metal deposited on a magnet is bad news, of course. If it's grayish mushy stuff without any hint of shavings or chips, that's better than the latter. Noise prevalent "on the gas" means under load, almost certainly generated by the gear teeth, but originally caused beyond doubt by misalignment from bearing deterioration. Early pinion bearing noise is high-pitched compared to ring gear bearings, as pinion spins several times faster than the ring gear and axles (3.55 times, etc.). Ring gear noise almost always increases under load, early-on disappearing when coasting, off the gas. Late-stage will show noise constantly: it is then IMPERATIVE to go into it.

There is incredible strength inherent in a driving gear-set's structure. Think of tightening a bolt to 100 ft-lbs as you probably have done, really tugging on that torque wrench. Consider an engine developing 300 ft-lbs: in first gear @ perhaps 3 to 1 gear ratio, the pinion bearing is transmitting 900 ft-lbs to the ring gear, which in turn is hitting up the axles with 900 X 3.55, way over 3000 ft-lbs! This is how I get "gut-feel" for what's going on.

Be aware there is a reason why a used center section is for sale: BEST, it came out of a low-mileage wreck. Worst, it, too, is no damned good. Usually, bone yards guarantee against leaks, cracks, noise, but that's little consolation for the guy who installs it and then must rip it out again.

Regarding your trip: A more educated guess on my part would necessitate actually witnessing the offending condition, and even then I have been wrong in the past often enough to be wary. I would hate to mislead you, and be remiss if I did so. How much driving will you do before the trip? Base noise results during that time on your decision to do it. Spearing "dinner" in a barrel of water often satisfies hunger. I hope we win this one! Good luck! imp

The metal deposits are just sludge, nothing more than fine particles at least from what I can tell, it just seems like quite a bit more than what there should be. The whine is honestly not all that bad, it is mostly just the heavy deposits that worry me. Once it warms up in the next few days here (-10 F) i'll crawl under and take another look.
Have always been amazed and how much an engine/trans/suspension can handle, 3,000 ft-lbs no wonder things start to fall apart.
The one I'm looking at is supposedly 100% reman, not just a used diff, with a 2 year warranty. The company is about an hour from where I grew up, typically very honest hardworking people there, not to mention I could just drive and pick it up myself and save shipping, but again even if 100% reman, could have been reman'd with cheap parts.
My trip is actually a couple months out, so plenty of driving between now and then, but once I'm at my destination I will have a very hard time getting parts which is why I want things settled now, but not a bad idea to keep an ear out for if things get any worse. Will keep updated if anything changes.
Thanks again!

 

[MrPulldown]

too bad you can't just remove the rear cover to inspect.

 

[imp]

too bad you can't just remove the rear cover to inspect.

@MrPulldown

I am wondering how he knew about/felt consistency of sludge formed without doing that? imp

 

[shane10]

@MrPulldown

I am wondering how he knew about/felt consistency of sludge formed without doing that? imp

I pulled the cover about 15k miles ago when I changed the oil because I had seen some lighter deposits on the fill plug magnet, everything looked fine, but again I have very little knowledge of the internal workings of the diff. I pulled just the fill plug again to see if anything had changed and the deposits were much heavier on the magnet, but still no chunks, just the metal sludge.
I wouldn't be against pulling it again but like I mentioned earlier, kind of hard to diagnose when I don't know what I'm looking at

May well be wishful thinking but I'm hoping to hit 300k with this truck, which is why I was on board with dropping 1K for a full reman diff. The engine is very clean, no sludge/carbon build up anywhere, no rattle, but am fully prepared to pull the engine to redo the chains if needed. Trans is still shifting very smooth. Have redone pretty much the entire suspension all around over the last couple of years, so I already have a decent amount invested into the longevity of the vehicle.
Anyways, maybe it is time to have a professional look at the diff to give me a better of idea what NEEDS to be done, thanks again for the insight

 

[imp]

I pulled the cover about 15k miles ago when I changed the oil because I had seen some lighter deposits on the fill plug magnet, everything looked fine, but again I have very little knowledge of the internal workings of the diff. I pulled just the fill plug again to see if anything had changed and the deposits were much heavier on the magnet, but still no chunks, just the metal sludge.
I wouldn't be against pulling it again but like I mentioned earlier, kind of hard to diagnose when I don't know what I'm looking at

May well be wishful thinking but I'm hoping to hit 300k with this truck, which is why I was on board with dropping 1K for a full reman diff. The engine is very clean, no sludge/carbon build up anywhere, no rattle, but am fully prepared to pull the engine to redo the chains if needed. Trans is still shifting very smooth. Have redone pretty much the entire suspension all around over the last couple of years, so I already have a decent amount invested into the longevity of the vehicle.
Anyways, maybe it is time to have a professional look at the diff to give me a better of idea what NEEDS to be done, thanks again for the insight

@shane10

Please bear in mind that inspection performed by one having much experience along the line i always a good idea, but not infallible. Look, observe, feel for discrepancy, seek visible evidence, check freedom of movement, smoothness, all good, but.......the future unfolds as it chooses. In my book, I judge the noise degree of severity, on what I have found internally in the past....if beyond still usable acceptable level, In tear things apart.

Usually, after that degree of intervention, I will replace expendable parts like bearings and seals, often regardless of visible defect, including (especially) seals.

Just my way, but gotta say, in hundreds of thousands of miles driven, the worst failures I've experienced were associated with tires.


imp

 

[donalds]

especially) seals.

I like using ford seals
Why not do it once right

 

[shane10]

Well, did an oil change today and dropped the lower pan for no other reason other than I had a spare gasket laying around, was not too happy to find bits of the timing cassette hanging out in there, so as of now my main concern has shifted from the diff to the timing chains... Will need to decide what to do with her as I can see things getting fairly expensive/time consuming at some point soon. I have noticed a recent rattle at startup for no more than a second on cold starts, no rattle after that, who knows when the guide broke.
Thanks for all the input, will keep updated if I end up pulling the engine earlier than I was hoping