Test 4 Series Posi
Hey guys, I just pulled my 12 bolt out of my truck and found that my pinion welded itself to the outer bearing (previous owner obviously drove it with no oil) is bad. I knew I had an issue, but thought it was the carrier. I don't see and physical issues with the carrier, so was wondering what I could do to test the posi out and see if the carrier is still good. Anyone have any benchtop tricks? I know the posi was working, just seemed clunky, which now I find is the pinion bearing moving. Was planning on changing the gears, but if the carrier is good, that would save me $450!
Thanks in advance! :metal: |
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Stock GM posi.
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If it's stock out of a 1967-72 truck... it will not have a Gov-lock.
It will be a spring clutch limited slip. Gary |
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I think the OE posi cases were supplied by spicer. Overhaul parts *might* be reproduced. For a while you couldn't get the clutch disc.
The pinion bearings rely on lubrication thrown by the ring gear. They really suffer when the fluid level is run low. |
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Used my press to get the pinion out, and found out why my axle had issues. Looks like the bearing ate the pinion shim. Bits and pieces fell out of the pinion shaft as it dropped out. Oops! :lol:
I grabbed an Auburn Posi off Summit, not going to even try to rebuild the stock carrier. My gears thankfully looked clean, so when the rebuild kit shows up with the carrier, it all gets to go back together. :metal: |
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Picture of your Positraction unit?
I put one axle in the vise pointed straight up and drop the posi onto it. Put other axle in from top and see if you can turn it with just the flange. If you can could use a rebuild. If you have to use a lever of some kind between two opposing lug studs to rotate it, probably OK to run as is. |
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Here's some pics. Looks to be an Eaton Posi. It actually looks OK, all the gears are clean and the ring / pinion were clean. Might just see if anyone wants it, could easily be rebuilt, or just pull the posi out and use it as a 4 series open carrier.
Did run into one issue - I can't get the pinion bearing off. I tried my gearing puller a few different ways, even to the point of just pulling the bearing off so it's just the race on the pinion shaft - it wouldn't budge. Probably going to ave to heat it up pretty good and try again. Once that is off, I can press a new bearing on and put the rest of the 12 bolt back together. Going to attack it again tomorrow. |
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When putting it all back together, you will need to know the thickness of the old pinion shim...How are you going to do that....
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Can you take pics on your measuring, I never seen that done before....thanks.
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There are actually some really good articles online to show that, better than me taking crappy cellphone pics! :lol:
Here are two from Hotrod.com that have helped me over the years: http://www.hotrod.com/articles/gm-12...install-guide/ http://www.hotrod.com/articles/1005c..._shaft_housing Lots of info. There was even an article in C10 Builder's Guide last month that walked thru the process. Definitely need specialized tools, and they aren't cheap for the good ones. I have the Summit one, it's an $80 setup, and it's just OK... but the good set is over $300 (!!) and I don't do this very often so can't justify the cost. If I open my shop like I plan to next year, I'll probably spring for it. Hope that helps. I'll try to take some pics too if you need. |
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There's an old saying "keep the pinion shim with the housing". Changing bearings, differential case (carrier to some) does not change the pinion depth to ring gear relationship. Gear sets are manufactured to known measurements too. Their replacement theoretically does not change pinion depth (unless marked + or -)
How many axles have perfect pinion depth from the factory? Not many. It certainly doesn't hurt to check it and adjust it. edit to what Youngpup said, working on Dana axles; test bearings are essential since the shims are the side bearings on the case. (under the race on the pinion) |
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And yea, I'm going to hone out the other old pinion bearing I have and use it to test. Easy way to check before anything permanent like pressing on the new bearing! Now, hopefully I can get the old bearing that's stuck on there off soon :no: |
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Cut off wheel and a big chisel are your friend
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Man, I'll tell ya, they don't make rebuild kits the way they used to. All the bearings and shims have been fine, but so far I've had to swap crush sleeve (wrong part) and now the pinion nut (damaged threads). I haven't had much time to get this thing back together as summer is the busiest time of year when you work at a school, but this is really making this take forever! Had to order a pair of pinion nuts from Summit so I could get this done. I need my truck back dammit!!! :lol:
Anyone else have issues with the JEGS 12 bolt rebuild kit? |
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