Rear-End Upgrade Plan, Sanity Check Requested!

Discussion in 'Transmission & Driveline Topics' started by wpatterson9, Jan 9, 2021.

  1. big gear head

    big gear head Veteran Member

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    Find out how they intend to weld it. If they are going to MIG weld it with steel wire then pass on it. If they are going to stick weld it with steel rods then pass. Welding cast iron must be done right or don't do it at all.
     
  2. 67johnny

    67johnny Veteran Member

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  3. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    It's not a huge change.
    Figure a 1 deg chang on a 24" run is only 13/32" at the furthest point
     

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  4. hd_cat

    hd_cat Member

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    My advice is to consider the cost of upgrading the existing rear end assembly and compare to a crate assembly. The amount you mention $1K is around half the cost of a crate rear end assembly. Depending on how you drive, you might consider aftermarket axles, C-clip eliminators would be a good investment as well. I chose the Strange 12-Bolt assembly with 3.73:1 Gears, yes it's expensive, but I should never have an issue with breakage. Regardless of the path you choose, strength/durability should be number 1, if you're not racing, consider the gear ratio, the 3.42 for the 8.5" ring gear 10-bolt is a great option for a mild engine, you won't believe the difference in acceleration, but your highway RPM will be significantly higher. Don't forget to change the driven gear for the speedometer, which should be a direct swap, if you choose the ratio from the factory options (3.08, 3.42, 3.73). Good luck with it, I'm happy with my choice and should only have to maintain it for the life of the car. The photo shows the installation with a 1" Addco Swaybar.
     

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  5. big gear head

    big gear head Veteran Member

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    Yes, it can shorten the life of the gears and axles. I've seen rear ends that were bent slightly and the whole differential was bound up so that it wouldn't turn free. I also know of a guy who had his rear end narrowed and the guy didn't get it exactly straight when he welded the ends on and the axle splines wore quickly.
     
  6. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    For just over $4k you can get custom built to your specs Ford 9" axle from Quick Performance like mine i had built by them

    Axle housing ...Chromemolly axle tubes and billet steel big bearing housing ends

    Billet steel housing

    Welded on bracing to increase structural strength

    Heavy duty billet steel leaf spring perches

    Center section ... Yukon aluminum carrier

    Billet pinion support

    Billet yoke

    Billet full spool

    3.89 gears

    Axle shafts .... 35 spline hvy duty axles

    S10 disc brake conversion
     
  7. wpatterson9

    wpatterson9 Member

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    @big gear head , Will do and thanks for the heads up. I'm hoping the shop will come through. They've received many positive reviews and specialize in muscle cars. If not, no big deal, I've got a few other places around here that could do the work but are 45min to 1hr away. Not opposed to traveling for good work but if the same quality is right by, all the better.

    @hd_cat , Thank you for the advice and your setup looks great! I did price out the cost of buying new vs. rebuilding what I have. After I compared both, I found that I'd be able to come out ahead slightly if I buy the parts and pay for the labor to install. At one point I did consider doing the labor myself but the wall I wasn't going to pay to overcome was purchasing the measurement equipment. I couldn't really justify buying tools that I would use only a handful of times. The plan for my build is going to keep the car relatively mild; 400-450 HP at most. Add that with the fact that my days of being a 6' x 225 lb. invincible 20 year old fueled by piss and vinegar are long, long gone... I'm thinking the car should be able to stand the test of time.

    @muscl car , That is a nice setup!!
     

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