Pros & Cons of converting GM 8.2 10 bolt to posi - Chevelle Tech
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post #1 of 11 (permalink) Old May 25th, 12, 10:24 AM Thread Starter
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David
 
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Question Pros & Cons of converting GM 8.2 10 bolt to posi

I have a GM 8.2 10 bolt 3.08. I see that there are posi carriers available for around $500 to $600. The ring & pinion have been replaced sometime in the past and look good. I recently replaced the spider gears. The axles and bearings look fine. This differential has been in my '65 El Camino for many years so I know it fits. Should I convert this to a posi or look for a GM 12 bolt. I have read here in the forums that 12 bolts are a rare find these days and aftermarkets units are pricey. I am planning a total suspension upgrade with UMI's Stage III package or some thing like it. Thanks in advance for the input.

David

David

1965 El Camino 327, M22
2000 GMC Sierra 5.3L,


But when you get right down to it,
no matter what you try
You deal the cards, give the wheel a spin
(Alan Parsons Project)
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post #2 of 11 (permalink) Old May 25th, 12, 10:58 AM
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Freddie
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

How much power are you making and how much traction do you have? If you are not making enough power with enough traction to break the 8.2 then go ahead and upgrade it. No need to spend the money on a 12 bolt if you don't need it, and if you like the 3.08 the just put in a good posi and be happy with it. You can get a good posi for less than the price you listed. What kind of driving do you plan to do with this car?
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post #3 of 11 (permalink) Old May 25th, 12, 10:58 AM
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

why do you want a posi? a 12 bolt is stronger, but all depends on the usage of the car, power

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post #4 of 11 (permalink) Old May 25th, 12, 11:16 AM Thread Starter
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David
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

I have a 327 with 2.02 / 194 70's era heads, holley street dominator manifold with 600 holley carb and headers. with a muncie M22. Been gear slamming for years with no issues, but not really drag racing, just playing my fellow motorists and turning heads. I am interested in doing some autocross and highway cruising.
Edit: also a late '70 - early '80 Crane fireball cam, with .465 lift & 270 deg. duration

David

1965 El Camino 327, M22
2000 GMC Sierra 5.3L,


But when you get right down to it,
no matter what you try
You deal the cards, give the wheel a spin
(Alan Parsons Project)

Last edited by AZ Light Speed; May 25th, 12 at 11:30 AM. Reason: Adding information
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post #5 of 11 (permalink) Old May 25th, 12, 11:56 AM
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Freddie
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

For auto cross use I recommend the Truetrac. I don't know if that is availabel for the 8.2, but I'll check. You might be limited to a clutch type differential. If that's the case I recommend the Eaton Posi or Dura Grip. Stay away from the Auburn.
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post #6 of 11 (permalink) Old May 25th, 12, 12:01 PM
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Freddie
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

No Truetrac, just the Eaton Posi or Dura Grip.
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post #7 of 11 (permalink) Old May 25th, 12, 2:16 PM
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Kevin
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

I upgraded my 3.08 10 bolt to a 3.73 with and Eaton Posi. For all around use it works great. If I was drag racing with a manual trans I would go with a 9" or some type of aftermarket 12 bolt.

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post #8 of 11 (permalink) Old May 25th, 12, 2:56 PM
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Stu
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

I put an eaton in mine, not too many miles on it yet but other than the fact it isn't free I can't see a down side to it.
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post #9 of 11 (permalink) Old May 25th, 12, 4:26 PM
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Aaron
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

I've got an 8.2 in my Chevelle
With an m20 Muncie I've gone low 12's with drag radials.
Car makes 376rwhp (about 440fwhp).
It's got about 15k+ miles with zero issues.

Richmond 355 gears, auburn posi, stock axles,

Aaron

1971 Chevelle. 355, megasquirt efi. On3 7875 turbo. 4l80e, py3600, 355 gears. C5 brakes, SC&C stg2+, hellwig bars, 04-06 gto seats. 546rwhp/450rwtq with 28% converter slip on 18psi!

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post #10 of 11 (permalink) Old May 25th, 12, 8:46 PM
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Brian
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

I'd just throw the posi in it and roll....should be fine.
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post #11 of 11 (permalink) Old May 25th, 12, 10:23 PM
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jim
 
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Re: Pros & Cons of converting GM 8.2 10 bolt to posi

Look at Tomsdifferentials.com, he has auburn posis for 375. He also has eatons but you have to call for price. That is what I'd do. Then drive that puppy. !2 bolts for the '65's are harder to find and generally more expensive than the later models because thry're an inch narrower. I have a '65 malibu and I'm putting a 12 bolt in it , but I'm making a little more hp with my big block, so I figured I'd beef up the rear. You should be fine if you don't start making too much more power. Good luck!
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