12 bolt id and 10 bolt id - Team Camaro Tech
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post #1 of 8 (permalink) Old Jan 3rd, 00, 02:21 PM Thread Starter
Join Date: Nov 1999
Posts: 21

Just by looking at a 10(8.5) and 12 bolt, what is different besides one have 12 bolts and the other have 10.
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post #2 of 8 (permalink) Old Jan 3rd, 00, 02:32 PM
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Location: West Richland, Wa. USA
Posts: 175

Size of the ring gear and number of splines on the axles. Oh yeh the 12 bolt is suppose to be stronger.

68SS ZZ4, 4sp T-10, 12 bolt, getting painted

78Z28, 330hp vortec, TH350, 10 bolt (just finished)
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post #3 of 8 (permalink) Old Jan 3rd, 00, 02:38 PM Thread Starter
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I mean can you visual ID a 8.5 10 bolt and 12 bolt just by looking at it, only the outside.
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post #4 of 8 (permalink) Old Jan 3rd, 00, 02:53 PM
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GM rearends use the same number of bolts on the back cover as on the ring gear. Just count the bolts on the back, and that's what it is. (it's much harder to tell the difference between an 8.2 and 8.5" 10 bolts, so be careful here.)

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post #5 of 8 (permalink) Old Jan 4th, 00, 02:09 PM
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Location: Ramsey, MN, USA
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Let me make a slight correction to JimM's post:

All Chevy rearends use the same number of bolts in the cover as in the ring gear. All GM rears do not! There is an Olds rear that may have 12 bolts on the cover, but it's a 10 bolt inside, so be careful.

70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

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post #6 of 8 (permalink) Old Jan 4th, 00, 05:05 PM Thread Starter
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I want to do is fake a 12 bolt, i know the shame, but my stock 12 bolt burnt up and i have 8.5 out of a nova
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post #7 of 8 (permalink) Old Jan 5th, 00, 09:25 AM
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Location: Houston, TX USA
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In regards to your post about faking a 12 bolt. True enthusiasts will always be able to recognize the 8.5" 10 bolt even if you change the physical appearance of the cover there are two distinct "humps" on either side of the housing (lower exremities) as you view it from the rear that would identify the rearend as a 10 bolt. Go proud with your 10 bolt or go deep ($$$$$$$) for another 12 bolt. Here is an idea for you. Buy a 12 bolt out of a later Chevelle and hack off all the odd shock and control arm mounting points and then weld on perches for the leaf springs. The perches from Moroso are only $20 and will allow the use of multi leaf or single leaf springs. You can get the Chevelle rear ends at most salvage yards for $150 complete from brake drum to brake drum.. I did this setup for a friend with a '68 and you unless we told you, you would never know the difference by looking at it.. The rearend is a little wider (1.5-2") but my friend runs the 15 x 8 ralleys and there is no clearance problem at all. e mail me if you want to know more. I can also tell you where to get rear discs for next to nothing..
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post #8 of 8 (permalink) Old Jan 6th, 00, 03:34 AM
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Join Date: Jun 1999
Location: MA, USA
Posts: 460

SS, Whats wrong with your 12 bolt. Did parts actually break or did the posi go bad. You can buy a Chevelle 12 bolt cheap as Go69 says. If yours doesn't have broken parts but is only worn you can use the carrier from the Chevelle rear in yours and sell the Chevelle housing and axles to a Chevelle owner as spares. If not use the Nova 10 bolt. Theres no shame in having a 10 bolt. If you like to say you have a 12 bolt rear then its going to cost something to say it. If you don't need the burnt 12 bolt then put the 10 bolt in, be happy, sell the 12 bolt and buy something else your car may need. BTW, Scooter is right on with his info. Not many people know that some Olds 12 bolts have 10 bolt carriers
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