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81 Differential Question

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Old Feb 1, 2007 | 10:23 PM
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Default 81 Differential Question

One of the caps has a hairline crack. Is the case junk or can I replace the cap. I think I know the answer but there is always hope.
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Old Feb 1, 2007 | 11:02 PM
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GTR1999 would be the one for this question..

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Old Feb 2, 2007 | 12:02 PM
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If you had a cast diff 63-79 you could replace just the cap with a HD one. Some machining would still be required. Yours being an aluminum dana it's not that easy. The bearing bores are machined with caps in place. Finding one that would bolt on with the proper rock would be a lottery at best. The 80-82 dana diffs were identical for 4spds and auto except for the pinion flange and stub axles. I would try to find a used one from an automatic and rebuild it.
Mike
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Old Feb 2, 2007 | 12:07 PM
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Good advice
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Old Feb 2, 2007 | 05:29 PM
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are you 100% certain it's a hairline crack and not the casting? I've seen them with some weird patterns on them.


Mike, what's different about the pinion flange? Does the automatic use u straps?? The autos and manuals (and all 82s) all use a 1310 pinion joint so that's not the difference. The automatics 80 & 81s do use y straps on the stubs.

Last edited by Twin_Turbo; Feb 2, 2007 at 05:31 PM.
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Old Feb 2, 2007 | 06:15 PM
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My mistake, only the 80-81 4spd driveshafts use a 1330 u-joint on the front joint. All the driveshafts use the 1310 u-joint on the rear. You are correct, the pinion flanges are the same.
The 80-81 auto halfshafts use the 1330 u-joint, the manual and all 82 uses the 1350 u-joint. All of them use straps.
Mike
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Old Feb 2, 2007 | 11:59 PM
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No straps on 81 or 82. Not sure about 80. I just ordered a used case from Bair's $100.00

I try to post some pics
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Old Feb 3, 2007 | 10:11 AM
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indeed, all pinions 80-82 use the caps..not the straps/u bolts, the 80-81 manual and all 82s use caps on the stub axles, the 80-81 automatics have u bolts there.
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Old Feb 3, 2007 | 12:47 PM
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Marck,
What you are calling caps is what I am calling straps. Should be calling them retainers. 80-82 doesn't use the u-bolts anywhere.
80-81 auto halfshaft 1330 u-joint retainers with 1/4 threads
80-81 4spd and 82 all 1350 u-joint retainers with 5/16 threads
Mike
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Old Feb 3, 2007 | 01:12 PM
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Mike,

I was thinking the same thing when I read over your message again LOL. Same thing happened a while ago in a keisler thread by george kull LOL. That's why I call the large things u bolts since they are tightened by nuts.

You're correct, the 80-81 autos had the smaller halfshaft and threads (and threaded holes in a different location so you can't redrill them....NICE!!!) ...I messed up there.
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Old Feb 5, 2007 | 08:04 PM
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Got the new case today. Let's see if there are any surprises with it. Hope not!!!
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