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Discussion Starter #1
So Im wondering since Ive pulled this 8" chunk and there is no visible issue and everything moves smoothly, not one bad tooth on the ring or gear, could a pinion bearing still be bad. Before I pulled it, there was a good leak coming from the pinion housing, up front. Ive read over and over about a seal failing because a pinion bearing has failed. But the test I see for checking the condition of the bearing.... grabbing the drive shaft and looking for play in the yoke by trying to shake the driveshaft....have left me seeing otherwise. Every time that I have yanked around on the driveshaft, I have no play, no movement, just small back and forth turning movement(the backlash). So my question is why would this seal fail? Age? After tearing through this entire rearend, redoing the entire brakes, new axle bearings, I cannot figure out what the issue would be.
 

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Typically when they go bad they wobble and that's what destroys the seals. You can't really test it by wiggling the driveshaft, you need to test it by trying to wobble it with the yoke itself. Sometimes put a bit of pressure on it with a jack to see if it deflects to much (don't overdo it!!) the 9" ones are pretty indestructable - when failures happen its usually because tha axle seals go - the fluid runs out the axle end, then the unit overheats or ruins the bearings and it all goes south after that. One of my least favorite jobs due to the smell of rear end fluid!!:cry:
 

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Stinky rear end fluid?!?....EEEEEEwwwwwwwwwwwwwwwwwwwwwwwwwwwww...is it a "brown" colored fluid? Is it leaking explosively or just dribbling....seriously, the rubber in the seal could be original and it just got hard and leaks...not all that hard to replace it.
 

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Discussion Starter #4
What do I need to do to replace it? Mark everythings relations? Pull the 1-1/16" nut? Will the yoke just come off then or am I going to need a puller?
 

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Okay....first remove the drive shaft, and then clean all that you can with something like brake cleaner and get the threads for the nut as clean as you can (a brush is desirable) and count the threads exposed and write them down. Next use an impact and remove the nut, the yolk should slide off (might need a tap or two) then remove the old seal...if the fluid is real full you may have a little come out the front...be ready with a drip tray or pan. Once the old seal is removed, clean all the surfaces on the housing and tap the new seal in place (in the past, I have used a little sealant around the edge of the new seal to insure I don't have a "leaker" when I am done, and then clean off excess sealer with brake cleaner or solvent) reassemble the yolk and tighten the nut until you have the same amount of threads showing, DON'T OVER TIGHTEN IT! There is a crush sleeve inside that supplies the load to the bearing, so you want to keep it as much the same as when you took it apart.
 

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Did you carefully check the condition of the pinion pilot bearing? (The one on the back side of the housing.) According to the article posted above, that's the most common failure point in the 8" rear. Probably wouldn't be easy to detect by feel from the yoke end of the pinion, but it creates a very noisy condition, which is consistent with what you've posted earlier.
 

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Did you carefully check the condition of the pinion pilot bearing? (The one on the back side of the housing.) According to the article posted above, that's the most common failure point in the 8" rear. Probably wouldn't be easy to detect by feel from the yoke end of the pinion, but it creates a very noisy condition, which is consistent with what you've posted earlier.
And the assembly is easily removed by unbolting the flange by the yoke and pulling the pinion/bearing assembly out.
 

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YEP - I don't think tuggin/twisting on the ol yoke is gonna really give it away (INSERT JOKES HERE...)
 

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Discussion Starter #10
I can pull the pinion assembly out through the front?... I was told it wasnt that great of an idea, being that theres a certain science to shimming it back correctly... maybe though...he was wrong...maybe its not... iver never done it before
 

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Discussion Starter #11
The whole thing is kind of baffling to me, when i pulled the chunk and axles, everything looks to be redone not to long ago. everything has matching paint and there was no sign of metal shavings in the old fluid
 

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I can pull the pinion assembly out through the front?... I was told it wasnt that great of an idea, being that theres a certain science to shimming it back correctly... maybe though...he was wrong...maybe its not... iver never done it before
Yep, the whole thing comes out through the front, the shim can be re-used and it seals with an o-ring that is behind the shim (further inside).
 

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Discussion Starter #13
How difficult is the job? Easy enough for a first timer? I mean I catch on pretty quick,lol. I want so bad to just say screw it and give up on the cat, but something inside me still wants her to purrrr....ahahhaha
 

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5 bolts and it's in your hand, couldn't get much easier than that. If you take it apart you from there (which you'll want to do to check the bearings), you'll need to either be careful about how tight to make the pinion nut upon reassembly (if you re-use the crush sleeve) or change to a shim pack instead and then properly shim for the right turning torque.
 

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You can re-use the shim on the 5 bolt flange if you are re-using the original gears. You might be able to reuse the crush sleeve if torquing the pinion nut to spec yields the correct turning force (measured with a inch-pound torque wrench). You should be able to find instructions on this procedure online.
 

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