TheExaminer

I've got an old Auburn posi carrier with 155k that one guy is telling me is bad, and another telling me it's good. The guy who's telling me it's good has 45 years experience rebuilding trans and rear ends, the other guy I don't trust too much! But for my own experiment, I'd like to know how many foot pounds it takes to turn a healthy carrier--like if you mount it on a mock axle and put a torque wrench on it when it's not in the car? And what does the difficulty/ease of turning tell us if anything? Seems like worn gears might be easier to turn, and twisted gears/bearings might be hard to turn.

big gear head

The Auburn is one of the worst differentials out there. If it's good today it might be on it's last good day and tomorrow it might be scrap metal. With that many miles on it there is a good chance it's almost gone, and no way to rebuild it.

I think most of the time about 40 foot pounds is what the break away is for a limited slip differential.

TheExaminer

LOL... Yeah I keep hearing crap about Auburn on here. A few guys say they've had good luck with them. What happened was, allegedly the original axle housing was bent, so I had to get a new (used) assembly. I took the guts out of the old assembly, and was checking to see which parts could be reused because the used on I bought will need to be rebuilt eventually. I thought I might try to rebuild it myself with the old carrier in case I screwed it up not much would be lost. I need to learn this crap. BTW, the guy that told me the housing was bent is the same guy who told me the carrier was bad. I don't trust him. Right now I'm new to most of this, but I'm learning in leaps and bounds, and am getting tougher to bull crap every day. But my question is, how can you tell for sure a housing is bent? When you look down the tubes it's like looking at a bulls eye. Not a trace of bend. I set the housing on jack stands and measured four different ways. Not all the measurements were identical for both ends, so it may be bent, but I don't know how absolutely flat my garage floor is either. Any more scientific way to measure it at home?

big gear head

If the rear end is out of the car then put the differential in it with a set of axles. Bolt a set of wheels on it and set them on the floor. Measure the distance between the wheels in a place that is easy to measure. Rotate the housing without disturbing the wheels. If the measurement changes as the housing rotates then it is bent. Do this several times so that you can be sure that your measurements are true and you are not accidently moving things around.

Have you read the thread in the FAQ about 10 bolts sticky about setting up a set of gears?

TheExaminer

Ok. Yeah, I can do that. Thx! I still have the diff bearing caps and axles, I'll set it up and chock the wheels. The only thing I don't have is the bearings that go on the carrier. Would that make a difference or make the carrier wobble around enough to skew the test? I guess not since the axle bearings are still in place. No, I've not read the tech on setting up gears, but I've read other pages about it. There's a great 10 bolt rebuild thread on here with plenty of pics and great descriptions. My biggest worry is setting up pinion depth and backlash, and pre loading the pinion bearings. I can do it, and I understand the concepts, it just can be tedious. But that's a ways down the road, a few months at least. The posi I have in there now is working ok for the time being, it just likes to make a few noises it's not supposed to..... But if my old housing isn't bent, I can clean it up and work on it little by little as I go at my own pace, then put it in whenever I want to. Here's a nice little rule of thumb picture I found for setting up gears.

big gear head

You will need the bearings on the differential to check the housing. The differential will need to be tight in the housing and the axles will need to have the c clips on them and be held tight too. If anything moves around then your measurements are going to be off.

Whoever made that picture that you posted got it backwards. If you have root contact then you need to decrease the pinion shim, not increase it. Same thing with the face contact, they got it backwards. The way they set up the picture isn't very helpfull because they used oval shapes to show the contat. That's not what you are going to see on your gear. It will have tapered ends on the pattern that will favor the root or face. That will tell you if you need more or less pinion shim. Also changing the backlash makes very little difference in the pattern. The way they show it you can make big changes in the pattern by changing backlash.

TheExaminer

Ok, thx for the tips. When I was looking at a loose ring and pinion that I have here last night I was having a hard time figuring out why it seemed backwards from what the picture was telling me, so what you said makes sense. I think the oval shape was just something they photoshopped to illustrate it more clearly, the real thing is a little cloudier. But the carrier bearings for that rear end are long gone. If I ever do a rebuild set up I'll need old reamed out bearings to set things up anyway, maybe I can get some from a garage or machine shop. But its not a huge deal right now, it can wait. Thanks for your help!

big gear head

You don't need set up bearings for the differential. They get pressed on once and that's it. The inner pinion bearing is the only one that gets pressed on and off durring the set up process.

TheExaminer

Yeah I know, I was talking about the pinion bearing for the setup. Usually helps to have old mock ups to set the depth and etc. I just thought if I ever got some old ones from a shop they might also have some old carrier bearings to use for the housing test. One crisis at a time though, I'm chasing a coolant leak and intermittent code 23 deal now.