12 bolt or not? - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

 
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post #1 of 14 (permalink) Old Mar 4th, 02, 06:33 AM Thread Starter
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I am thinking of putting a 12 bolt 3.73 posi rearend in my 67 camaro that currently has a 10 bolt "limited slip" with stock gears. My question is should I go through all the trouble to swith to the 12 bolt rear end, I mean I would have to switch leaf springs from mono to multileaf along with alot of other "stuff" that comes with conversions, or should I just rebuild the 10 bolt stock rearend with new axles and posi unit with the 3.73 gears? Any info is appreciated
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post #2 of 14 (permalink) Old Mar 4th, 02, 09:55 AM
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Figure on a rebuilt 12-bolt with a new Eaton posi to run about $1500, unless you have a line on something less expensive. Multi-leafs, $225. Hardware (if needed, U-bolts, shackles, bushings, mounting pads, shocks, brake parts, etc, $???). You'd easily spend from $1500 to two dimes for this job. It's up to you if it's worth it. If it were me, I'd probably rebuild your 10-bolt with a Eaton posi, and some 3.73's. Then order new replacement mono's...maybe some slapper bars would help the mono's and keep tires from bouncing around on blast off.

Let us know what you decided and why.
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post #3 of 14 (permalink) Old Mar 4th, 02, 10:07 AM Thread Starter
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Well I guess that is a no brainer Sleepy-69. I am going to rebuild my 10 bolt with a posi unit and 3.73 gears. You mentioned replacement mono leafs....Are these leafs built strong that the originals? And where can I order these leafs from? Would you suggest buying new hardened axles for the new posi unit or should I use the stock ones? Any idea on how much a shop would charge for the installation of the posi unit and the gears?
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post #4 of 14 (permalink) Old Mar 4th, 02, 11:35 AM
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Brother 67 RS...check into eatonsprings.com for replacement mono's. Yes, my guess is these would be equivilant or superior to the originals. This is a good company with good quaility springs and advice.

Gears, Posi and labor? How about $750 +/- for a bench job...meaning they don't have to remove the rearend...you just drop it off.

Axles? I can't answer, but the stockers are mighty strong.

Good luck with your rearend!
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post #5 of 14 (permalink) Old Mar 4th, 02, 03:04 PM
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67's dont have the staggered shocks. I'd advise three leaf "mono replacement" springs to control the wheel hop unless you are using traction bars.
Mono springs are lower spring rate than multi leaf.
I bought a 12 bolt rear end with 4.88 and posi for $300. out of a local newspaper ad.

I guess I was lucky, but check around, you might get lucky too. I'd rather spend money rebuilding a 12 bolt than a 10 bolt, if you can find one.
If you just can't find a 12 bolt. Look around for an 8.2" rear, they are stronger than your 8.2" rear.
Your 8.2" rear can work OK if the power and abuse isn't too bad.
David

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post #6 of 14 (permalink) Old Mar 4th, 02, 03:40 PM
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dave, just one correction, i believe you meant 8.5" rear, just wanna clear it, as to not confuse 67RS. I didnt want to sound like a smarta** though.

anywho, if you switch to a 12 bolt, use 5 leafs instead of three, IMO the ones i have are lame, but it could be other factors.
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post #7 of 14 (permalink) Old Mar 4th, 02, 10:31 PM
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(8.2" vs 8.5")
The 8.2" vs 8.5" refers to the diameter of the ring gear. The advantage to the 8.5" is that it is stronger than the 8.2".

67-69 camaros with 10 bolts are all 8.2"
70 10 bolts are 8.2 (Nova and 67-69 Camaros are interchangeable)
71-74 Camaros & Nova are all 8.5"

Cheers

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post #8 of 14 (permalink) Old Mar 5th, 02, 04:27 AM Thread Starter
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Will the 8.5" fit in my 67 10 bolt rearend?
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post #9 of 14 (permalink) Old Mar 5th, 02, 08:07 AM
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There's an article you can download from CarCraft.com that illustrates replacing the Camaro 8.2 10 bolt with an 8.5 for $400. You need to get a housing from a 72-75 Nova. They claim it is nearly as durable as a 12 bolt.
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post #10 of 14 (permalink) Old Mar 5th, 02, 05:45 PM
 
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Most likely the 10 bolt you have in the car is a 8.2" ring gear.The carrier for this is smaller than the 8.5 and I don't think the 8.5 will fit. Have heard that adapters (?)are sold for this conversion.I am doing the same conversion in my 67.
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post #11 of 14 (permalink) Old Mar 6th, 02, 03:55 AM Thread Starter
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Thanks for all the input! I think I am going with the 72-75 Nova rearend and putting in the 8.5 posi unit with 3.73 gears. Thanks alot Coach420 for sending me that article from carcraft.com.
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post #12 of 14 (permalink) Old Mar 6th, 02, 04:50 AM
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I believe the correct year nova's with the 8.5 rear are the 70-74. '75 was a model change. I put a 8.5 out of a 70' nova in my car.

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post #13 of 14 (permalink) Old Mar 6th, 02, 08:34 AM
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Due to the strike in 1970 some Novas were
equipped with 8.2". Just get a 1972 Nova Diff. as stated previously its 8.5" for sure
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post #14 of 14 (permalink) Old Mar 6th, 02, 10:21 AM
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I was at a rear end specialty shop several months ago and the guy showed me the difference between a 12-bolt axle and an 8.5-inch 10-bolt axle. The 10-bolt's axles were much beefier - thicker and no taper. The axles are the 12-bolt's main area of weakness.
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