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A forum for the owners and enthusiasts of General Motors B-Bodies from 1977-1996, but dedicated to the owners of 1977-1979 Impalas and Caprices. Join up now!


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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

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    agrumpydwarf
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  agrumpydwarf Sun Aug 30, 2015 9:33 pm

    I have a 1978 Caprice Classic Landau with a 10 bolt 4.75" bolt pattern w/ 2.41 gears listed on the tag. Can this be changed to a 5x5" bolt pattern by just changing the axles or will it require a complete rear end change from a wagon? Thanks
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  GM B-Body Forum Mon Aug 31, 2015 9:35 am

    Depends on if you have the 8.5 or 7.5 rear end or the 8.75 rear end. Spline count changed in the late 80s i want to say 87 or 88 so anything under that will be the same, best bet is to just swap the entire rear end.
    Check this out if you havent yet: https://www.gmbbodyforum.com/t153-gm-8-5-10-bolt-swap-from-a-96-impala-ss

    And this if you dont know what rear end you have: https://www.gmbbodyforum.com/t333-how-to-id-your-rear-end-gm-10-12-bolts-7-5-8-5-8-75-8-875
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  Sweet Seventy9 Mon Aug 31, 2015 10:51 am

    Wagon rear ends do not interchange with sedans or coupes.

    For direct bolt-in rear ends, here's what RPO codes to look for in the 91-96s:

    Ratio RPO Code. Application
    2.56 GM8 Std. Roadmaster LT1
    2.73 GU2 Std. Caprice L99 (exc. 9C1)
    2.93 GW9/GU3 Std. Caprice LT1 (exc. 9C1), Opt. Roadmaster LT1
    3.08 GU4 Std. Caprice 9C1/LT1 (Police), Std. Impala SS
    3.23 GU5 Opt. Caprice L99, Std. Caprice 9C1/L99 (Police)
    3.42 GU6 Std. 91-93 Caprice 9C1/L05, Std. 94+ Fleetwood w/V4P
    3.73 GT4 Std. 91-92 Fleetwood Brougham w/V4P

    *V4P = 7,000 lb. trailer towing package... look for a hitch.
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  Myloth Mon Aug 31, 2015 3:49 pm

    The swap from a late model B Body ie. Impala, Roadmaster that has 8.5 Posi is best they are better made than

    the older 8.5s. Either way it's an easy swap I swapped a Roadmaster Posi into my 79 with my neighbor in the driveway

    with stands and hand tools. The original 7.5s are puny compared to a newer 8.5 night and day.
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    Post  agrumpydwarf Mon Aug 31, 2015 11:35 pm

    Thanks for the information and the additional links. I think I have an 8.5" by looking at the casting horns on the rear end. My first priority at this point is to get it to roll. Long story short, I have changed the front spindles (purchased at Street Trends) to a 2" drop that required a 12" rotor because of the outer bearing. Now I have 5x5 on the front and 5x4.75 on the back. Currently I am just trying to get them to match so I can purchase some wheels that will be the same. Most places seam to have a larger selection of sizes in the 5x5 pattern. Trying to attach some picts.
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  agrumpydwarf Mon Aug 31, 2015 11:43 pm

    Trying again for picts. Can't seem to get them to upload. I have reduced them to 160KB and it still shows an over size error msg
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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

    Post  Sweet Seventy9 Tue Sep 01, 2015 2:04 am

    Use 3rd Gen Camaro 1LE front brake rotors to retain the 5x4.75 bolt pattern.

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    Change stock 5x4.75" bolt pattern to 5x5" bolt pattern Empty Re: Change stock 5x4.75" bolt pattern to 5x5" bolt pattern

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