I have been a member on here for quite some time now. I traded in an 07 expedition for a 2010 F150, and just traded the F150 for an 06 F250 Lariat. I needed something to haul a 35ft gooseneck car hauler.
I picked up the 06 powerstroke at a good price at 86k miles. I now know why it was traded. I don't think it even towed anything in its life, hitch was clean, no marks on the safety rings, no marks on the electrical connections indicating rubbing.
I noticed a whine at 50 mph or so, I assumed it was front wheelbearings. Changed those out, sound is still there, took in to Ford, they diagnosed it as rear diff noise. They wanted 1800 to replace the LSD packs and the bearings. I took it to a local shop, same job for 1100 bucks. When we cracked the diff open to inspect, it was loaded with metal shavings, the ring gear/pinion are toast.
Long story short, 1800 bucks, rebuild the whole rear diff. Perusing through the threads, I notice I am not the first person with rear diff problems at 80-100k miles. They offered to put in a Jasper for 3100, but I don't think I put enough miles on it to warrant the upgrade.
What is up with these trucks failing at such low mileage?

 

Here is my comfort zone. I figure at least $2000 a year per vehical on parts replacement. Its true every year things don't go bad but at some point those numbers will be spent. I wrench on my own stuff.
Sorry for your bad luck once you get her up and running you'll smile for sure.

 

I really don't see that many differential failures on the forums, but I'm sure the 105k fluid interval Ford specifies doesn't help. I would go 40-50k max on differential fluid, and only 10-20k on the factory fill since the differential is wearing in. After I changed gears, fluid was changed after 1500 miles of break in and its now been about 20k so I'll be changing it again soon.

 

Yeah, I don't see that much either.
Bad luck!

 

yeah i learned the check interval lesson the hard way. after 160k miles the 01 f250 i got from my dads rear end jumped about a foot in the air doing 60 miles an hour. thankfully i managed to keep it from rolling or going in the ditch. i somehow managed to limp another 5 miles to my friends house by which time the rear dif was smoking and it locked up twice more. when i got the cover off there was no fluid left and around 5lbs of metal chunks and shavings from the carrier which was destroyed and the ring and pinion.
i then found out that none of the fluid levels on that truck had ever been checked other than the oil.
i managed to go to a salvageyard and find a axle out of a 99 f350 that i had to swapout yokes and grind the studs off but it was only 400 bucks so i got lucky there.

 

My Dana 80 blew up for unknown reason at 230k, but differential was all greasy when I bough the truck at around 190k, so I guess it had some problems before.
In my case the bearing cage disintegrated for no apparent reason and took the gears with it. Having lot of mechanical experience I read quite a lot about those differential and they seems to have pretty stupid design. The low end differentials have crush sleeves for bearing tension adjustment. What kind of adjustment is that?
My Dana, what suppose to be top of the line differential judge adjustment on the torque it takes to turn the bearing. You have to squeeze the bearings with well over 1000 ft-lb and than measure the resistance by turning dry bearings. Than to make adjustment you have to spend about 1hr to take whole thing apart to replace one adjusting shim.
I spend whole day playing with it and rechecking.
How many mechanics do you think will go that far?

 

BTW I bought the highest quality pinion gears with Timken bearings for $540 delivered overnight.
It pays to surf the net and be DIY mechanic.

 

What shim are you changing after installing the crush sleeve? All shimming should be done ahead of time with the pinion installed with no crush sleeve, and the crush sleeve is used only in final assembly. Also, you don't check preload with a dry bearing, you lube it liberally before assembly with gear oil. Its a pretty solid method and not a lot of wasted effort when done correctly.

 

To the original poster, there are various reasons the differential goes before it's time Abuse, water/condensation in the gear oil, crappy front pinion bearings used by Ford, etc. Never seen a front-pinion bearing on a Ford without some overheating being obvious that was a Timken bearing. I've see a whole slew of NTN bearings used for that front pinion bearing, but Timken in the rest of the unit. Once that front pinion bearing goes, the pinion preload goes out and the pinion wobbles, ruining the rear pinion bearing, and the ring/pinion gears are toast. If it's not caught quick enough, it WILL be a costly repair.

If the rear-end makes noise on deceleration (or highway cruise), that front pinion bearing is going. Once it starts to whine all the time, it usually means a complete rebuild is in order if you want it to last.

He's saying that the Sterling (low end differential) uses a crush-sleeve, and that his Dana 80 uses shims.

What he's not saying is that without putting everything together multiple times, there are variation markings on the pinion so that using the old shims, you can add or subtract the correct amount of shim and get depth correct on the first try, and get very close on the preload. Except of course, when you've mangled/overheated the housing or the old shims and you have to start from scratch. And the pinion nut is only 466ft/lbs, not 1000+.

http://www2.dana.com/pdf/AXSM-0053.PDF

No where does this say "dry bearings". It doesn't say lube them either, but who rotates a dry bearing with 466ft/lbs on it?

The Dana with it's shim-based preload is by far a better design than the crush-sleeve setup, and does take some time to setup PROPERLY.

On the other hand, the crush-sleeve setup can be done fairly easily too, you just have to know what you're doing. I've done some 8.8" Fords that are setup like the Sterlings, if you are patient, they come together quite well.

Same for the Danas. They aren't very hard, you just need the right tools, and PATIENCE.

 

You can get shim sets for most crush sleeve axles.

 

Dana is not using crush sleeves and per my research never did. The manual says to check the tension on dry bearings. They do have some grease on them from factory, but for used bearings that have oil on them the procedure is quite different.

 

I went by the Differentials manual from Randy's Ring and Pinion and it says to oil the bearings before assembly and to NOT use dry bearings. Strange the procedures are different. Everything else I've read says to oil the bearings too.

 

http://www2.dana.com/pdf/AXSM-0053.PDF
Here is manual for Dana 80 rebuild. It asks only for putting some oil on the seal. page 3-10
If you'd like to rebuild the differential per this manual you'd have to spend few thousands dollars on special tools, like box spreader and so on. I found DIY sites that gave tips how to do it without them, but than I have no way to fully check perfect assembly.
Still wonder how such complicated differential fails so often?

 

BTW. Who knows what is reasonable amount of steel wear out on the differential?
After rebuilding the differential I keep an eye on it. It was getting pretty warm at the beginning, but last run in Bay Ara traffic made it 170F, what I consider not bad. Than I pulled the magnetic plug couple of times and had "steel mud". Very fine steel particles that made my fingertip dirty. Not enough to make measurable amount, but some. Is that normal, or shall I pull the cover out to inspect? Have about 2000 miles since the rebuild and plan to change the oil at 5000.

 

The pinion bearing went out on our '83 and took the rest of the diff with it. I found it was MUCH cheaper to pick up a complete axle ('91 model) from a salvage yard than it was to have the unit rebuilt. I could change the axle in my driveway. I don't have the expertise to set the bearings and gears.

It might be worth a trip to a salvage yard to see what a complete axle would cost. If the door code matches I believe it should swap regardless of year model.