10 bolt to 12 bolt questions

Discussion in 'Transmission & Driveline Topics' started by Paulis 72, Dec 26, 2015.

  1. Paulis 72

    Paulis 72 Veteran Member

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    Hi guys. After much hunting around here in Oz, I managed to track down an original 12 bolt posi for my 72 Camaro with 3.73 gears.They are as rare as rocking horse poo down here. It seems in really good condition but has no brakes. 2 things Im wondering is whether I can use the same tailshaft once I fit the 12 bolt and whether I can just swap my whole drum brake assembly onto the 12 bolt? The drums on my 10 bolt are fairly new and work great so I hopefully I can just do a swap.
    Thanks
    Pauli
     
  2. big gear head

    big gear head Veteran Member

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    The brakes are a direct fit. They are exactly the same on the 10 and 12 bolt. As for the drive shaft, it might be a little too short. Your '72 would have the 8.5 10 bolt, which has a slightly longer pinion shaft. The 8.5 drive shaft is usually about an inch shorter than the 12 bolt and 8.2 10 bolt drive shaft. If you can find a '70 drive shaft then it will fit.
     
  3. mrdragster1970

    mrdragster1970 Veteran Member Lifetime Gold Member

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    Have you checked into a new replacement unit?? even a direct fit 9"??
    If they are that rare, and pricey??? maybe a new unit would be cheaper, even shipped????

    Good luck.

    .
     
  4. Paulis 72

    Paulis 72 Veteran Member

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    Thanks for the info gear head.
    I looked into getting a new one but it was approaching $5000 landed over here. Way out of my budget.
     
  5. fatkid_racing

    fatkid_racing Veteran Member Lifetime Gold Member

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    I'm sure I'll get flamed for this, but there's not much strength difference between the 8.5 10 bolt and the 8.875 12 bolt. The 12 bolt will eat more power than the 10 bolt. The 12 bolt has slightly larger bearings on the carrier and has better axles, but dollar for dollar a well built 10 bolt will perform just as good as any 12 bolt. If you've got the 8.5 version of the 10 bolt and can afford to have a good set of axles and a carrier shipped down under you might be ahead.

    Here's a good read from a different forum. http://www.pro-touring.com/threads/23690-10-bolt-vs-12-bolt
     
  6. badazz81z28

    badazz81z28 Veteran Member

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    If I were to do it all over again, I would buy a ready to go moser rearend. I would imagine a stock 12 bolt being as rare as it is cost more than a superior moser 12 bolt. The 10 bolt can be built stronger. I build mine with 30 spline axles/posi.

    However an equally built 12 bolt is stronger than an equally built 10 bolt. However a built 10 bolt will suite the needs of most street bruisers.

    IM trying to sell my built 10 bolt if your interested
     
  7. big gear head

    big gear head Veteran Member

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    I think the big problem here is the location. South Australia is a long way from here. I have sold a few complete Moser 12 bolt rear ends to people in Australia and New Zealand, and the shipping, plus duty and taxes was really high. It's much easier for us to buy stuff here in the US.
     
  8. Peter Wilson

    Peter Wilson Veteran Member

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    What would shipping cost from North America to OZ ? I have a really nice " COZ " 12 bolt for a 70 with 3.73s/ Eaton . I paid $ 2000 Canadian which would be equivilant to about $1600 US and I figure its about the going rate for one . I couldnt imagine $3000 for shipping
     
  9. badazz81z28

    badazz81z28 Veteran Member

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    Comes with the hobby I guess. Members that are in the middle east, Australia, UK, Canada etc. need to realize that some of these parts are already expensive and transporting them over the ocean amplifies that cost. If you want an old american car restoration project, you need to have expendable income to support it. I would hope these cars have more value outside the US because of the cost associated with the parts
     
  10. bracketracer-78

    bracketracer-78 Veteran Member

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    I pulled out a 12 bolt and replaced it with a 8.5. For my next rear I'm taking a look at the 14 bolt. The ring gear is 10.5 and the pinion gear is supported like a 9". I do not know how the floating axles will work in a dragracing application.
     

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