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GM B-Body Forum, 77-79 Caprice/Impala Forum

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    Gear Ratio ?

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    jimzagg
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    Gear Ratio ?

    Post  jimzagg on Fri Apr 07, 2017 6:47 am

    Newbie here ! My 1984 Delta 88 Daily Driver Has a rebuilt 307 with a Holley carb and an Edelbrock Performer intake and an HEI with vacuum advance. It has a turbo 350 with a stock converter. My problem is with the 2.41 gears in the 7.5 rear it is just too lazy to drive normally on the road. I'm thinking about switching to either 2.73 or 3.08 gears. Not knowing much about 7.5 rears my question is do I need to switch the carrier in the rear? Have any of you guys done this and any preference on ratios?

    JIM

    BrokenBlazerDave
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    Re: Gear Ratio ?

    Post  BrokenBlazerDave on Fri Apr 07, 2017 6:48 pm

    According to Motive Gear's website the carrier break is between 3.08 and 3.23 for the 7.5" rear end. So with your numerically lower ratio's you would not need to change the carrier. To keep the cost down I would probably go with the 3.08. You would get the most bang for your buck around town and still not rev too high on the highway and not have to replace the carrier. The only reason to replace the carrier would be if you wanted a limited slip. With all the vehicles listed you shouldn't have too much trouble finding a cheap rear end with the gears you want and maybe even a posi.
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    jimzagg
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    Gear Ratio ?

    Post  jimzagg on Sat Apr 08, 2017 5:35 am

    Thanks Dave ! I was kind of leaning toward the 3.08 gears myself.
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    Re: Gear Ratio ?

    Post  GM B-Body Forum on Sun Apr 09, 2017 4:52 pm

    Yes a 3.08 is perfect, i ran a 3.08 for a few years. Started out with the original 2.41 in the 7.5, swapped in an 8.5 from an impala ss which had the 3.08, then now ive got 3.90s. The 3.08 was perfect all around. Its not my daily so i went with 3.90s which arent bad for the street but the highway i can hit about 3200rpm at about 70


    _________________
    1979 Caprice Sport Coupe, 400hp Vortec 350, Th350, GM 8.5 w/disc brakes, 3.90 gears Detroit Truetrac, 2.5" stainless duals w/ x-pipe, Dynomax race bullets.
    1984 Caprice Sedan, 305 motor, 700r4
    1978 Caprice Sedan, 305 motor, th350
    1993 L99 Caprice, 4.3 v8, 4l60 trans
    1972 Ford F-100, 302 windsor, c4 trans
    2001 BMW E46 330i, 3.0L

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