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deep gears for a Jag irs differential

Discussion in 'The Hokey Ass Message Board' started by coilover, Nov 7, 2012.

  1. coilover
    Joined: Apr 19, 2007
    Posts: 696

    from Texas

    Has anyone done it or know of someone that has? Have a 1st generation Jag rear in a 57 150 2dr (2.88:1 ratio) that is way too shallow for the LS2 and OD trans. Would like 3.92 or 4.10 so final in OD would be right for highway cruising. It looks like a Dana 44 r&p on the 3.92 and deeper carrier would fit and hopefully a carrier with a limited slip. Thank you.
  2. kennkat
    Joined: Aug 25, 2011
    Posts: 1,385


    You are correct, it is a 44... There are differences... in axle spline.. early or late 44... but most stuff fits within those guidelines.
  3. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 9,182


    My Jag is 3.54:1, works well with OD and 235:75:15 tyres. Here are OEM Jag ratios

    Attached Files:

  4. fiftyv8
    Joined: Mar 11, 2007
    Posts: 5,394

    from CO & WA

    Also check out Elplacko's thread recently posted where he is fitting a Jag IRS into a 57 Olds from memory, there was a comment I recall regarding interchange between Dana 44 and the simliar Salisbury crownwheels/centers.

    I got an early E type IRS and hit has 3.54:1 LSD.

  5. Easiest to find is probably the 3.54 gears from a V12 car 70's-80's version. The V12 are also limited slip, so you just get the whole center section and swap it out. Lower gears plus the extra traction compared to your current 2.88 open diff.

    I am foggy on the exact details, but the Dana 44 ring gear bolts are different size than the Jag. You can get special bolts to make it work. Search for more details. The Dana 44 gears can be made to work, but it is not a bolt-in swap. There are a few hiccups in the process. Sorry I can't recall the exact details.
  6. nick_s
    Joined: Apr 11, 2006
    Posts: 436

    from Ohio

    are you running a really tall tire or something?> LS1/Auto camaros without "perfromance axle" were 2/73 gears with 26" tall tires. they went down the highway just fine :shrug:
  7. Weasel
    Joined: Dec 30, 2007
    Posts: 6,696


    Not entirely correct - it's one of those 'it must be true because it's on the internet' kind of deals. The Jag is a Salisbury - it is similar to a Dana 44 but it is not a Dana anything. They did however use a 2.88 Dana 44 in 1985-1987. The 'posi' in the Salisbury is a Powrlok. If the mods had not shut down my Jag suspension thread because they deemed it untraditional - for suspension designed in 1957 and in hot rod use since 1964:confused:, you would have found plenty of information. I posted photos on that thread showing the differences between the Salisbury and the Dana 44 where you could easily see what is what.

    There was a 3.77 in the o/d original S type (1963-1969) but numerically higher than that is going to be tough to find.

    The XJS from mid 1993-1996 (with the AJ6 engine or the V12) had a 3.54 posi with outboard brakes, which overcame my one major objection to the Jag IRS. The carrier housing also has lugs to accommodate the parking brake cable brackets and a fancy finned aluminum rear cover. More info here....
    Last edited: Nov 7, 2012

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