What is This 12 Bolt Posi Out Of?? - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 12-08-2004, 06:22 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
What is This 12 Bolt Posi Out Of??

Guys,
I traded a 10 bolt rearend to a guy 2 years ago for a 12 bolt (he traded cause the rear end I had was a bolt in to his 56 Chevy). I can't figure out what this 12 bolt is out of. Here are the details (please help I am trying to sell it and need details).

Axle flange to axle flange 63 1/2", backing plate to backing plate mount 58 3/8" it has leaf spring perches that are 38" center to center.

Casting numbers are as follows B116 (on the back side), GM6 (top of front side), 3852980N (lower front side).

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 12-09-2004, 02:53 PM
Kevin45's Avatar
Just one of the guys
 

Last journal entry: Garage Toys
Last photo:
Join Date: Jul 2002
Location: Urbana, Ohio
Age: 57
Posts: 3,058
Wiki Edits: 0

Thanks: 1
Thanked 15 Times in 15 Posts
Got any pics of it?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 12-09-2004, 03:24 PM
M&M CUSTOM's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Transmission identification
Last journal entry: 1988 Suburban, the project continues.
Last photo:
Join Date: Mar 2003
Location: Northwest Pennsylvania.
Age: 42
Posts: 2,230
Wiki Edits: 9

Thanks: 0
Thanked 1 Time in 1 Post
How about just the stamped axle ID code from the front of the passenger side axle tube?
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 12-09-2004, 03:35 PM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls, Washington
Posts: 5,217
Wiki Edits: 9

Thanks: 100
Thanked 130 Times in 121 Posts
Hey Royce, I'm at work (on lunch break of course, your tax dollars at work..) and did a search for GM differentials. Our system is extremely tight but I did find the site below that would indicate the code GM6 (RPO Code ?) is a GM truck rear with a 4.22 ratio. I say truck mainly because of the ratio and the site URL has trk in it, he he.

There were some other interesting sites that may decode the 3852980N code you listed as well, but I was limited there as well.



http://www.drivetrain.com/GMtrkratio_posidata.html

Good luck, Larry

That link isn't working when I try it from here, if you have problems just go to the drivetrain.com home, go to the bottom of the page, then to the "Free" section for "What ratio do I have" link.

Guess I need some practice inserting URL's.

Last edited by 68NovaSS; 12-09-2004 at 03:45 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 12-09-2004, 04:32 PM
M&M CUSTOM's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Transmission identification
Last journal entry: 1988 Suburban, the project continues.
Last photo:
Join Date: Mar 2003
Location: Northwest Pennsylvania.
Age: 42
Posts: 2,230
Wiki Edits: 9

Thanks: 0
Thanked 1 Time in 1 Post
I found that the Code "3852980N" 12 bolt posi-traction differential was installed in many different cars in the mid to late 60's.
Quote:
Axle flange to axle flange 63 1/2", backing plate to backing plate mount 58 3/8" it has leaf spring perches that are 38" center to center.
An axle search with the wheel mounting measurement you gave listed no results. Chevy trucks measure 62 inches.

An axle search with a 58 inch backing plates measurement gave me:
'61 Chevrolet Impala, '65 Cadillac, '66 Buick Wildcat, '66-67 Chevrolet Big Car, '69 Oldsmobile 88.

An axle search with spring perches 38 inhes on center resulted in nothing either.

Either a large leaf sprung car, or truck would be my best guess.
The stamped code would tell the gear ratio, year, vehicle, and when & where it was made.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 12-10-2004, 02:08 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
Guys,
Thanks for the input. The gear ratio is 3.31. Don't the truck rear ends have a different cover/shape than car rear ends? It is definetly a round cover. I do have pictures and I will post them (I have to reduce the size cause they are too big).

Did the early coil spring cars (don't have one handy to look at) have mounting ears on the "center" section? My thought is that this rear end is out of a wagon, Chevelle, Monte Carlo or Impala and someone removed the coil spring mounts and welded on leaf spring mounts. The guy I traded had it in his 56 Chevy (but was too wide for the rims he was using).

I will work on posting a few pictures.

Thanks,
Royce
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 12-10-2004, 03:55 PM
Ghetto Jet's Avatar
current hot rod: CTS-V
 

Last journal entry: Lets Get Started With the Improvements
Last photo:
Join Date: Nov 2003
Location: Pennsylvania
Age: 28
Posts: 1,726
Wiki Edits: 0

Thanks: 10
Thanked 5 Times in 5 Posts
Quote:
Originally posted by camaroman7d
Guys,
Thanks for the input. The gear ratio is 3.31. Don't the truck rear ends have a different cover/shape than car rear ends? It is definetly a round cover. I do have pictures and I will post them (I have to reduce the size cause they are too big. Royce
Yes the truck rears do have a different shape and they aren't as strong as the 12 bolt car rears. The reason being the truck rears have a smaller diameter pinion shaft than the car rears.

this shows the two, second and third column. http://www.differentials.com/pdfs/46.pdf
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 12-10-2004, 04:42 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
Ghetto,
Exactly as I thought. It is a car rear end. I didn't want to grind/sand the paint off (I am selling it) to see if the stamp is on the front of the passenger side tube.

What photo editors do you guys use? I can't get my picture small enough to fit here. I guess I should change the setting in my camera.

Royce
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 12-10-2004, 04:54 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
picture 1
Attached Thumbnails
Click image for larger version

Name:	12bolt1.jpg
Views:	3874
Size:	32.6 KB
ID:	3287  

Last edited by M&M CUSTOM; 12-10-2004 at 07:41 PM.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 12-10-2004, 04:55 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
picture2
Attached Thumbnails
Click image for larger version

Name:	12bolt2.jpg
Views:	4304
Size:	45.2 KB
ID:	3288  

Last edited by M&M CUSTOM; 12-10-2004 at 07:42 PM.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 12-10-2004, 04:57 PM
camaroman7d's Avatar
Member
 
Last photo:
Join Date: Dec 2003
Location: Vacaville, California
Age: 47
Posts: 2,245
Wiki Edits: 0

Thanks: 3
Thanked 9 Times in 9 Posts
picture 3
Attached Thumbnails
Click image for larger version

Name:	12bolt3.jpg
Views:	4929
Size:	43.6 KB
ID:	3289  

Last edited by M&M CUSTOM; 12-10-2004 at 07:43 PM.
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 09:03 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.