Need advice...

I have a Ford 9 inch out of a old Bronco. It had a slow leak around the pinion seal area. I decided to take it apart and noticed that the ring and pinion had a lot of wear and the "detroit" locker was really just a terrible weld job that was starting to crack. So I removed it from My XJ and then took it to a local Trans/Driveshaft shop and told them to fix it. They told me the only thing left that was good was the housing. Which is when I decided, instead of just an overhaul, lets make it strong for offroading. So he suggested Grizzly Locker, Yukon 31 spline axles, new ring/pinion gear (4.86), new case, etc.... basically everything except the housing itself. They complete the overhaul and I pay them ~$2100 for the job. Before I take it home, we inspect it. It was all sealed up and I let him know I'm happy with the way it looks. So I load it up in my trailer and take it home for install. Only showstopper during the install was the shop removed the brake lines and forgot to re-install them. Since he's not open on saturdays, I just dropped by the local auto shop and bought some new brake lines and install them myself. So finally the moment of truth. I take the XJ for a spin and its riding awesome. It's quiet, smooth and riding better than I could ever remember. Well after driving about 5 miles, I notice a sudden loss of power. I thought it was the engine, since it's been a few months since its been driven. So I let off at about 60mph and coast down to 40 ish, to try to assess whats going on and then BOOM, rear locks up. It was a scary situation as it fishtailed pretty wildly before it came to a stop, but I managed to get it just out of the lane. For a moment I was thinking brakes since I just put on those new lines, but after seeing smoke coming out of the case, I knew what it was. I had a buddy come drage me off the shoulder into the grass and I had a tow truck drop the truck and I off back home. Later on I unscrewed the fill plug and confirmed there was no fluid in there. Only good news is, nothing appeared broken from the small fill hole, but I'd wager that I won't be so lucky when it's all said and done. First and foremost, I know I should've checked first. I would've saved myself a lot of heartache and (assuming at this point) money, if I would've checked for fluid, instead of assuming it was already filled. However am I wrong for thinking they should've filled the unit with the proper fluid, or at least mentioned to me that it needs fluid? I'm certain they are going to try to put it all on me, but is it standard practice not to put the proper fluid in an overhauled rear end thats been torqued down and sealed? I don't understand why this wouldn't be any different if I took it to them installed on a vehicle. I'm going to leave it all together because I'm sure they are going to want to inspect it, only thing I touched was the fill plug. I'll be calling them on Monday to tell them the news. I feel at a minimum they should give me the replacement parts at there cost, and I shouldn't have to pay for labor. It sucks knowing that I probably just threw $2k down the drain and with my luck it won't be just something simple like bearings welded to the pinion shaft. So, how do you guys think I should go about handling this?

Edit. I was able to remove the carrier and verified the pinion bearings were the problem. They got too hot and fused with the pinion. I saw very little shavings mixed in with a small amount of oil in the housing. Only visual damage I see is some wear on the pinion gear. Everything else looks and operates as normal. It still smells like hell

Wow, that sucks. I guess I could see them not filling it on a loose axle due to an unknown pinion angle, or to keep oil from leaking out the breather should the axle get turned upside down while transporting it home. However, if that's their policy, I think they would have at least told you about it. Most shops that I've seen set gears provide you with very detailed break-in instructions, often times in writing. I would think the instructions would include filling the diff with a particular weight of oil after installing it on the vehicle, if that was in fact required.

That being said, you still should have checked the oil level after installing it to make sure it was where it needed to be after setting your pinion angle...

engines dont come full of oil and fuel, neither should diff's. a full diff will spill all over the place in transit.

i think it comes down to, did they install the diff? if they put it under the vehicle, and sealed up the diff, it needs fluid.

if they loaded up your diff into the back of a pickup truck for you to install, that's on you!

in this situation, i would put red tape over the diff as a warning, just to prevent myself from making these kinda mistakes.

No I removed it from the vehicle and dropped it off still assembled (with fluid). It's not that I forgot to check, I was dumb enough to assume it wwas already done. There were no directions, no warning, not even a reminder. Just a "thanks for your business." Expensive lesson to learn. And I'm just bummed I dropped $2k just to spend another $500-1000 to fix it again

I'm afraid I would have to side with the shop on this one. It would have been nice if they had told you it was empty but I would expect a diff that was not installed in a vehicle to be dry when delivered.

Damn, well I respect the input, hopefully they have a kind heart and hook me up on labor or something. Thanks

out of curiosity, did it feel strange AT ALL, with zero fluid? i'd imagine it would feel grainy, and weak.

i'd love to see a pic, i bet the gears are bronze'd over (dont know the official term, imagine the differance between race take-off shocks, and brand new shocks. same finish, one's 'cooked')

There was some fluid at the bottom of the diff which is probably why there wasn't total failure of everything else. And with the warn out 35s on it I wouldn't have heard much, they howl. With the previous condition of the original rear end, it rode like a dream. Smoother, quieter, just as strong, until the heat built up. The pinion looks like hell. Carbon build up from the heat and that burnt clutch smell. I think the reason the damage was minimal was everything was new, and only making it a few miles, there wasn't much time for everything to build a lot of heat. Plus it went from riding fine to immediate lockup, on a cool night on warn tires, I think there was a relatively low shock to the rest of the components. I'll snap some pics.