Replacing 66 GTO rear end with corporate 8.5 inch - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old 11-21-2011, 04:44 PM Thread Starter
 
Join Date: Nov 2011
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Replacing 66 GTO rear end with corporate 8.5 inch

I have a 66 3.7 posi rear end in my car and I need to go to more of a cruising gear. I'd like to have a 2.73 to 3.08. I could just get the new ratio gears, but I think I'd have to change the carrier as well. Is there a "corporate" 8.5 inch rear end that is a bolt in? I like the idea of a stronger diff, and it seems that I might be able to find a posi rear end with the ratio I want for not too much money. All suggestions greatly appreciated.
Thanks,
Alan
Alan B is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 11-28-2011, 04:29 PM Thread Starter
 
Join Date: Nov 2011
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Nobody? Somebody must have done this swap. Even if we don't need the extra power handling, the flexibility on available gears and availability of low cost posis seems to make it worth considering.

If not, does anyone have suggestions for where to find 3.08 gears for an 8.2 10 bolt? Am I correct that I can buy a new posi carrier for that ring and pinion and be ready to go (once the rear end is set up)?
Thanks,
Alan
Alan B is offline  
post #3 of 9 (permalink) Old 11-28-2011, 06:24 PM
Former Moderator
 
ALKYGTO's Avatar
 
Join Date: Mar 2010
Location: Wentzville, Mo.
Posts: 2,893
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 16 Post(s)
Garage
For the cash outlay for the rear + the hassle why not consider an OD tranny? Automatic you could do a 200R4 w/an adapter plate or do one of the Tremec trannys for a stick.


Any similar year GM A-body will have a rear that will physically fit in your chassis, prolly won't be a posi, but more than likely will have that cruiser gear you are looking for. That would be the cheapest route.
ALKYGTO is offline  
 
post #4 of 9 (permalink) Old 11-28-2011, 07:49 PM
Administrator
 
05GTO's Avatar
 
Join Date: Oct 2004
Location: Deliverance, GA
Posts: 5,143
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Quote:
Originally Posted by Alan B View Post
I have a 66 3.7 posi rear end in my car
Is this the original 8.2 Pontiac or a Chevy 8.2?

Randy


05GTO is offline  
post #5 of 9 (permalink) Old 11-28-2011, 10:19 PM
 
jetstang's Avatar
 
Join Date: Nov 2008
Location: Niceville, FL
Posts: 3,376
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Garage
The 8.5 won't work in the car, they have metric chassis, or just don't bolt up, I know they don't work or everyone would be doing it. The 66 rear is 5/8" narrower per side than later rears, so keep that one. I think the break for the 3 series carrier is 3.36 or 3.23, so that's the lowest you can go for gear. 3.73 posi is very desireable. Should be able to find a usable carrier and someones takeout 2.76 gear. I sold my 2.56 rearend for $100, though single spin.

Burning rubber since 1982!!
My photobucket, lots of dif car pics.
http://s411.photobucket.com/home/jetstang
jetstang is offline  
post #6 of 9 (permalink) Old 11-28-2011, 11:19 PM
 
Join Date: Mar 2011
Location: Texas
Posts: 704
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
8.2 pontiac rears all use the same carrier, just requires a gear change, plenty of those lower 2.73 around. not so much for 3.08.
pontiac is offline  
post #7 of 9 (permalink) Old 11-28-2011, 11:33 PM
Administrator
 
05GTO's Avatar
 
Join Date: Oct 2004
Location: Deliverance, GA
Posts: 5,143
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Someone correct me if I am wrong, but didn't pontiac offer the 3.55:1 and 3.90:1, Chevy used the 3:73:1.



You can purchase a ring and pinion from Randy's

Randy


05GTO is offline  
post #8 of 9 (permalink) Old 11-28-2011, 11:42 PM
64-67 Expert
 
geeteeohguy's Avatar
 
Join Date: Feb 2008
Location: Fresno, California
Posts: 8,561
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 119 Post(s)
The 8.2 Pontiac rear does NOT use the same carrier. There are three different carriers: 2.56-2.78, 2.93--3.23, and 3.36-4.33. If you have a 3.73 ratio, it is indeed not a Pontiac ratio and you may have a Chevy rear end. Not sure about those. If a BOP ten bolt is what you have, you could "bolt in" a set of 3.36 gears and be set. If you want it more highway friendly, your best bet is a whole new rear end, bought used, on the cheap. The highway geared rears go for very little money, and can be found fairly easily and are a bolt-in deal. If you want a limited slip diff, the highway diffs with limited slip are out there. If you find an open rear, an LSD unit can be added. I swapped from a 3.36 open in my '67 GTO to a 2.56 posi (it was a freebee) and I love it.
geeteeohguy is offline  
post #9 of 9 (permalink) Old 11-29-2011, 04:18 PM
 
Join Date: Nov 2011
Location: Pasadena, CA
Posts: 18
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have a 12 bolt 2.73 posi out of a 69 El Camino that will fit your car. It was in my 65 for many years and I just bought the posi carrier a couple of years ago which I rebuilt. PM me if interested.

Mike

The hottest places in hell are reserved for those who in times of great moral crises maintain their neutrality.

-Dante Alighieri
Knuckledragger is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, Lemans & GTO Undercarriage, Frame, Transmission and Differential Discussions.

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
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:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Replacing Rear Quarter Window Chrome Sash? cgseaman 1964-1974 Tempest, Lemans & GTO Complete Exterior Body 0 09-16-2010 11:41 PM
Replacing rear tires with slightly different size, any issues? teamgs Wheels and tires 3 04-12-2007 07:56 AM
Replacing Rear Bumper Skin on 2004 GTO??? GoPujols5 2004-2006 GTO General Discussion 3 07-12-2006 10:11 AM
Despair - Corporate Spin Ricekiller The Lounge 2 05-15-2006 11:22 PM
18 inch or 17 inch wheels... Edel4011 Wheels and tires 27 12-23-2005 11:05 PM

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

 
For the best viewing experience please update your browser to Google Chrome