# Installing a new posi and gears?



## MichaelG (Sep 19, 2010)

Obviously when doing this it's has to be right. I've never done it nor even seen it done. I prefer to do all the work on my car myself but I'm afraid of tackling this one. Advice?


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## Matthew (Feb 11, 2011)

Michael, good thing you asked. This needs to be out-sourced to a professional. Watch a couple videos on it and you will see why. Matt


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## geeteeohguy (Feb 2, 2008)

I've done a couple of them and in the future I will source them out. A pro differential guy who does this a _lot_ is the best choice. It is a PITA, and gear lash settings are critical. Get it wrong, and you ruin the gears or have a noisy rear end. Better bite the bullet on this one and pay a pro. Hopefully, Old Pinion Head will chime in here.


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## FMFC motorsports (Mar 21, 2015)

I have a new 12 bolt posi, moser axle unit. It was put together by an idiot? U still would need to do ur own work


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## Pinion head (Jan 3, 2015)

Just a few things use here to build muscle era GM differentials....
two T&D deluxe Pinion depth tools (easy to knock out of calibration), a Kent Moore Pinion depth set for dealing with original early 60's GM gears. custom built build bench, line up bar, 30 ton press, various press plates, tubs and tubs...over 300 lbs of various cast side gear spacers organized in freezer bags to the .001, tubs of side shims, service spacers. Most important thing cant get from a youtube video or buying a few summit cheepee tools and winging it... having learned side by side with long time builders. even after building for years with a mentor, there can be challenges. 

The most challenging Salisbury style differential I've encountered in over 800 builds was one I went through it 3 times with 3 different sets of quality gears...not the cheap Chinese gearsets avail through so many sources today(won't use them). Local multi million dollar (expensive) drivetrain shop couldnt get the noise out either building with NOS GM gears. Only solution was to swap out housing for another same dated coded housing and build off it. Yes, had that housing in the stacks.


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## Goat Roper (Oct 28, 2014)

I wanted to add a limited slip diff to my '67 and keep the 2.93 gears.
I got so much conflicting info I finally said screw it.
Some said late '66 thru '67 is the proper width, others said any 10 bolt.
I talked to Ramjet and he said the limited slip won't work with this rear end.
I finally said screw it and just kept the original pegleg since you apparently can't do a ls with 2.93 gearing.


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## Pinion head (Jan 3, 2015)

Goat Roper said:


> I wanted to add a limited slip diff to my '67 and keep the 2.93 gears.
> I got so much conflicting info I finally said screw it.
> Some said late '66 thru '67 is the proper width, others said any 10 bolt.
> I talked to Ramjet and he said the limited slip won't work with this rear end.
> I finally said screw it and just kept the original pegleg since you apparently can't do a ls with 2.93 gearing.


Not true, every factory cone type 8.2 Pontiac Safe-T-Track carrier have ever owned went out either to a fellow restorer who need a tight posi for his car, or I used it in a 3.23 8.2 Pontiac rearend build. The same ratio carrier was used in mid ratio Pontiac 8.2 rears (2.93, 3.08, 3.23). There are however 2 different styles of the 4 pinion mid ratio 8.2 Pontiac carriers, the '66-69, and the late '69-72. late style has 1/16" larger ring gear holes and in factory applications use the LH thread ring gear bolt. the later style 8.2 carriers can be used with earlier GM or aftermarket gears by making 10 small brass bushings out of brass tubing from local hobby store. After installing the small bushings, wipe with blue Locktite on the threads of the new ring gear bolts and torque in increments.

The above, noted, usually build the 8.5 A-body rear for most '64-72 Pontiac A-body applications. The 8.5 A-body rearend is very hard to beat:
- the most pinion support of any factory A body rearend, 
- a multitude of aftermarket gears, posi's avail, along with modern tapered bearing bolt in axles
- performance proven record, ability to hold up where even strengthened nodular 8.2 Pontiac rears fail. 

all above make it a no brainier for performance street and strip use, ESP in applications where one looks under the rer of the car and one expects to see a cutout 10 bolt rearend cover.
For the true concours restored GTO's and Firebirds, will still go through an 8.2 Pontiac rear every once and a while, just finished building a type "O" Olds 10 bolt for a similar showcar build. Same deal for early GTO owners that are very stuck on driving with narrow repro redline tires and the early narrow 8.2 rear, still build them, but it gets costly.


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## Bensjammin66 (May 12, 2009)

As most have already said here it is the best roughly $200 in labor youll ever spend. Have a diff guy set it up. Im willing to tackle anything on my car besides internal transmission and differential work. Im just intimidated by it.


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## Rukee (Feb 8, 2007)

It's a wise man who knows his limitations.


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## Matthew (Feb 11, 2011)

Ben, if you can get a new posi carrier, gears and bearings in Ohio for $200, I need to know where in Ohio to take my next rebuild.  Matt


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## PontiacJim (Dec 29, 2012)

I just had my 9" Ford carrier assembled and gears set up. I dropped off all the new pieces I had been collecting to make a "bullet proof" (hopefully) center section. It was a 1 day turn around. Price -$125.00 plus a couple small parts I did not include for a total of $129.00.

The shop I went to specializes in building the 9" center sections for the Nascar racers as well as any other types of race car. He can build any type rear center section or rear end and he does manual trans rebuilds as well. Got to watch him build another racers 9" center section while I was there and talked with him about the set-up. Learned a bunch. He showed me a $2500 ring and pinion gear he was setting up. He seemed to really know his stuff and has been doing it for a long time. As a kid he used to race a 12 second '71 Camaro. He has customers that come from states away to get him to rebuild, change, or freshen up their gears.

That said, hunt around for some guy who works on race cars/hot rods, or ask around to get in touch with someone who does. I had to do some emailing to find this guy as he does not advertise. It was a 1 1/2 hour drive to his place, but I'm real happy with what he did and who can beat the price.


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