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10-17-2018, 09:59 PM
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#1 |
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Registered User
Join Date: Oct 2018
Location: Sioux center, IA
Posts: 81
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12 bolt rebuild
I have been searching the internet for the correct and proper way step by step how to rebuild my GM 12-bolt posi rear end.
I've got new bearings and new seals. It's going in my 67 short box Stepside C10 it is a truck posi rear end. I would like short simple answers please it would be so so much appreciated glad to be on this site I've read a lot of good information already that was has helped me with other issues again thank you. |
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10-17-2018, 10:51 PM
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#2 |
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Registered User
Join Date: Jul 2012
Location: Space Coast, Florida
Posts: 403
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Re: 12 bolt rebuild
Just rebuilt mine a couple of months ago. I did a lot of looking and bought a couple of books but never found a single source for information on rebuilding the 12 bolt truck. I can tell you what I found out about the required specs for setting up the rear end. But there are no short quick answers. Have you done any rear end work before? You will need a beam style inch pound torque wrench to check the pinion bearing preloading. You will need a two jaw puller to get the yoke off of the pinion. You will need some very long wrenches to set the pinion bearing nut preload. I used two 39 inch long 3/4 inch breaker bars and a 1 1/8" socket along with a plate I bought to hold the pinion while I torqued it. You will also need to remove the carrier bearings and pinion bearing and have new ones pressed on. Are there any major problems with the rear end now, or is it just a refresh?
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1968 SWB Step Side, Big Block, 4L80E , Running! |
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10-18-2018, 09:14 AM
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#3 |
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Registered User
Join Date: Jul 2012
Location: Space Coast, Florida
Posts: 403
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Re: 12 bolt rebuild
GM 12 BOLT TRUCK
Pinion preload torque with new bearings, 13 TO 15 inch / pounds Pinion to ring gear back lash .006" TO .010" Ring gear retaining bolt torque 55 ft. / lb. Carrier bearing cap bolt torque is 60 ft. / lb. Carrier bearing preload should be as tight as possible without hamming the side shims into place. (Tap in with brass or aluminum driver). When checking and setting the gear mesh pattern, it is best to go back the way it came apart if you are using the old gears, and there were no issues with the rear end other than wear. This is my 2 cents
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1968 SWB Step Side, Big Block, 4L80E , Running! |
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10-18-2018, 09:27 AM
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#4 |
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Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,709
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Re: 12 bolt rebuild
Technically I guess you could find short, simple answers on rebuilding a differential, but it is a fairly technical, precise assembly so you really need a technical precise and detailed set of instructions.
Entire books are written on the how to process so don’t expect one paragraph on a message board to get you there. But the good news is there are how-to’s all over the internet. Google away. If you don’t own a factory service manual for your truck, that is where I would start. Once you have a good, general idea of the process, then come back and ask some simple and precise questions that can answered in a short manner.
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44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax |
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10-18-2018, 10:48 AM
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#5 |
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Registered User
Join Date: Jul 2002
Location: St. James, MO
Posts: 1,239
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Re: 12 bolt rebuild
Why not get a copy of the factory overhaul manual?
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'69 Longstep K-10: 327/SM465/T-221/Closed Knuckle Dana44/12-bolt. |
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10-21-2018, 08:03 AM
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#6 |
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Registered User
Join Date: Oct 2018
Location: Sioux center, IA
Posts: 81
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Re: 12 bolt rebuild
Yes I have rebuilt one before but it was 35 years ago when I went to school for automotive. I have Googled away and all I get are guys with a half-hour story of what they did that day and very short little bits of information as for what they're doing with the rear end. Thank you very much for all of those who have gave me good information I appreciate it very much. I apologize for probably not clarifying some of the information, I'm new to this forum system I have never had a computer and I just recently have gotten this Smartphone. I have been looking all over the internet for manuals and I'm coming up empty-handed any ideas as to where I could look would be much appreciated thank you very much
Last edited by KMAT; 10-21-2018 at 08:05 AM. Reason: Need to add more info |
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10-21-2018, 01:55 PM
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#7 |
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Registered User
Join Date: May 2011
Location: mich
Posts: 654
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Re: 12 bolt rebuild
the book by jeff bryant is the best hands down, how to rebuild a 7.5 8.2 8.5 8.78
Last edited by hjewell2; 10-21-2018 at 01:59 PM. Reason: spelling |
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10-21-2018, 02:00 PM
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#8 |
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Registered User
Join Date: May 2011
Location: mich
Posts: 654
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Re: 12 bolt rebuild
Follow the Author
Jefferson Bryant + Follow Chevy Differentials: How to Rebuild the 10- and 12-Bolt Kindle Edition by Jefferson Bryant (Author) 3.9 out of 5 stars 43 customer reviews See all 2 formats and editions Kindle $14.02 Read with Our Free App Paperback $24.39 21 Used from $12.75 30 New from $18.85 |
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10-21-2018, 02:03 PM
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#9 |
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Registered User
Join Date: May 2011
Location: mich
Posts: 654
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Re: 12 bolt rebuild
Follow the Author
Joseph Palazzolo + Follow High-Performance Differentials, Axles, and Drivelines Kindle Edition by Joseph Palazzolo (Author) 4.3 out of 5 stars 93 customer reviews See all 8 formats and editions Kindle $16.17 Read with Our Free App Paperback $23.63 40 Used from $14.98 47 New from $18.05 |
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10-21-2018, 09:38 PM
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#10 |
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Senior Member
 Join Date: Aug 2017
Location: Chicago,il
Posts: 356
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Re: 12 bolt rebuild
I too would like my rearend rebuilt just because everything else on the truck will be brand new. I must have posi for the power I’m expecting. Can anyone recommend a good shop or person that does these in the Chicago/Milwaukee area?
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