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Thread: 9 bolt rears

  1. #1
    Join Date
    Jul 2010
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    york, pa
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    63

    Default 9 bolt rears

    I've heard different stories about the GM 9 bolt rears. Some people say they are stronger than a 10 bolt and then I hear the exact opposite. I myself had one in my GTA. It had a 383 in it and ran 12.4 @110mph and 11.4 @120 on the spray with a 1.8 60ft. the only thing i had done to it was a set of 3.73 gears because at the time there really wasn't any other upgrades for that rear. I'm curious to know how much power you can put to a 9 bolt thats been built before it lets go. I know there is more of a selection of aftermarket stuff for them now.



  2. #2
    Join Date
    Nov 2006
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    456

    Default

    The 9 bolt is slightly stronger than the 7.5 10 bolt. The 9 bolt used a Borg Warner 4 pinion differential which was quite a bit stronger than the 2 pinion Auburn that was used in the 10 bolt. The axles in the 10 bolt were upgraded to 28 splines fron 26 in '90, but the 9 bolt had 28 spline axles all along. The 9 bolt has bolt in axles where the 10 bolt used c clip axles. The ring gear diameter in the 9 bolt is about 1/4 inch larger than the 7.5 10 bolt, which also add strength. As far as I know there are still no major upgrades for the 9 bolt. You can get a T/A Performance alumunum cover for it, but that's about it.

  3. #3
    Join Date
    Apr 2010
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    Pittsburgh, PA
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    627

    Default

    hmmm...never heard of a GM 9 bolt...heard of 12 bolt obviously and 10 bolts.... 7.5/7.6, 8.2, 8.5 bolt-in (71-72 skylark/gs/cuttlas) and 8.5 c-clip chevy...
    axle tubes were pretty much all 3"' minus s10s and g-bodies which were 2 5/8?

    any more info on a 9 bolt? like what car/years did it come out of, and what would it be considered 8.2 or 8.5?

  4. #4
    Join Date
    Apr 2010
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    Pittsburgh, PA
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    Default

    n/m did quick google and answered my own questions..7.75 R/P 9 bolt 85ish trans am....cool i guess

  5. #5
    Join Date
    Nov 2006
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    456

    Default

    The 9 bolt is built by Borg Warner and was used in the F body cars from '85 to '89. It has the 7.75 ring gear with 8 ring gear bolts and uses a 4 pinion BW posi with cones. The axles are held in by pressed on axle bearings and bolt on retainers (no c clips). Most of them had disc brakes, but some had drums. A similar differential is used in the '04 to '06 GTO and new Camaro, although these use independant suspension instead of a solid axle.

  6. #6
    Join Date
    Aug 2004
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    Ontario, Canada
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    2,090
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    Default

    I've been told there was also a Dana 44 (with torque arm mount) available. Just how rare would these housings be?

    Ken
    If there is a hard way to do something, I'll find it!
    My other car is a Vega.

  7. #7
    Join Date
    Aug 2005
    Location
    Hamilton, NJ
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    Country Flag: Swaziland

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    there is and it is rare. a friend of mine just sold one for $1500
    Scott from NJ. Stay thirsty, my friends

    Vent Windows Forever! ... My junk, featuring the Red Dragon ... NastyZ28 ... NJ Camaros & Firebirds

    Feather-light suspension, Konis just couldn't hold
    I'm so glad I took a look inside your showroom doors

  8. #8
    Join Date
    Nov 2006
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    456

    Default

    The SLP cars got the Dana 44 and you could buy them over the counter at your GM dealer. I'm told that GM used the 44 to replace trouble rear ends under warranty too.



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