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Re: [oletrucks] Q's about rebuilding 3.73 posi 12 bolt

To: CLLLSLS@aol.com, oletrucks@autox.team.net
Subject: Re: [oletrucks] Q's about rebuilding 3.73 posi 12 bolt
From: Passnb4U@aol.com
Date: Mon, 10 Jul 2000 12:34:01 EDT
In a message dated 7/9/00 5:55:10 PM Pacific Daylight Time, CLLLSLS@aol.com 
writes:

> Hey everybody,
>  
>  Swapping out the TH350 and 3.08 10 bolt in my '79 Silverado for a 700R4 
and 
>  3.73 gov-loc 12 bolt. I'm sick of "one tire fires" and no snot off the 
line. 
> 
>  
>  The 3.73 unit I have came from a 76 chev 1/2 ton. One carrier bearing and 
> one 
>  axle bearing were shot so I've gotten all new axle and carrier bearings 
and 
>  axle seals. I'm thinking I should pull the pinion out and check the 
bearings 
> 
>  and atleast replace the pinion seal seeing as how I've got it down this 
far.
>  
>  The Haynes shop manual I have does not give very detailed info at all 
about 
>  rebuilding rearends. I've never actually personally had a rear down this 
far 
> 
>  and neither have any of my shop groupies I rely upon for advice. I do 
gather,
>  
>  however, that messing with the pinion nut is a delicate procedure, not to 
be 
> 
>  taken carelessly.
>  
>  Can any of you tell me how I should go about removing and reinstalling the 
>  pinion and also, I've always understood that shims are necessarry for 
proper 
> 
>  gear alignment. I've seen guys set up rearends before, I understand the 
>  principles, I even have some prussian blue from who knows where, but I've 
>  never done it myself. 
>  
>  I didn't pull any shims out of this rear when I tore it down. just two big 
>  thick precision washers(one is ruined from the bearing spinning on it). Is 
>  there some sorta "shim kit" I need to get to put this thing back together 
>  right? 
>  
>  Please help! Thanks,
>  
>  Dustin
>  '79 Chev 1/2 ton short wide
>  50 & 53 GMC 1/2 tons
>  48 GMC 3/4 ton 
>  48 GMC 1 ton


   Dustin,

  I've set up a few rearends, I'm suprised you haven't found any shims, but 
I've not done a "gov-loc"...least I don't think I have....did you look 
between the carrier bearing and the carrier?  Also, when you pull the pinion, 
they may be under the race in the housing as well.

  Best thing would be to get the GM shop manual or a MoToRs that covers your 
year model, the exploded views are priceless.

  To remover th pinion, you'll first have tpo remove the carrier..remove the 
pinion nut, and then pull the pinion gear out from where the carrier side is.

  If you notice shims behind any press fit races....take the old race and 
file it some so it will slide in and out of the housing, or the inside of the 
bearing so it will slide off and on the carrier or pinion (where ever a shim 
would be behind a press fit) to use as a "test" fixture"....quality bearings 
(Timken, BCA, etc) are all cut to within .001 of each other and the races 
rarely wear unless the bearings were run dry

  Set up the pattern starting with the old shim stacks first, then once it's 
right, put all the new bearings and races in, and recheck the final 
patterns....do you have a crush sleeve on the pinion?  If so, talk to a rear 
end shop and ask about a spacer for a crush sleeve eliminator, then you'll be 
able to set the pinion pre-load via shims, and not worry about the crush 
sleeve losing it's "crush" over time.

  Use a non-locking nut for the initial pinion setups and get a NEW pinion 
lock nut for the final assembly.

  Since you're able to read the contact pattern, the only "special tools" 
you'll really need are a 0-40 in/lb torque wrench and a mounted dial 
indicator to check backlash with...once you get the feel of the backlash 
setting and the correct pinion pre-load, you probably not even use them again 
until the final check.

  If you're really unsure of the pinion depth and can't make sense of the 
contact pattern, give me a holler, I found a website (that I have saved 
somewhere) that sells "unviversal pinion depth gauges) for $99.99 plus 
shipping, pretty good deal.

  Mike

  
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