8-1/4" Limited Slip

Transmissions and Rear Ends

  1. BudW

    BudW Moderator Staff Member

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    I was browsing for some parts for my ride, and ran across this:
    POSI CARRIER DANA SPICER 27 SPLINE TRAC LOC DODGE CHRYSLER 8.25 INCH 10 BOLT | eBay .
    Screenshot 2021-03-10 102557.png
    Chrysler's 8¼” differential, from '68 to '96 use 27-spline axles.
    '97 and up vehicles use 29-spline axles – which makes finding axles and limited slip carriers (for FMJ's) a bit hard to find, sometimes.
    The 8¼” Ring and Pinion Gear sets are the same from '68 and up.

    I did some digging and it appears Dana/Spicer has recently re-introduced the 27-spline limited slip carrier again. I might recommend anyone looking for a limited slip carrier for your 8¼” differential, to get one now, while they are still available – for I don't foresee this sticking around long (and hopefully I'm wrong on this).
    On top of that, this unit is the rebuildable clutch design instead of the metal on metal cone design that Chrysler originally used for our cars (that came with limited slip).

    Here is some details on the two units. Green is what will fit (8¼”) FMJ's and red will not (29-spline – DO NOT USE).
    Screenshot 2021-03-10 102457.png
    If you can't read the part number, it is d/s75101x
    Screenshot 2021-03-10 102519.png

    I think I might just grab one of these.
    BudW

    Edit:
    I just noticed it says this is for “all gear (ratios)” - but it is not. The 2.2 nor 2.4 gear ratio will not work with this carrier.
    If you have a 2.2 or 2.4 ratio, then this is the perfect time to upgrade to a 2.9 or lower gear set.
     
    Last edited: Mar 10, 2021
  2. Camtron

    Camtron Well-Known Member

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    I ordered mine from, Drivetrain America for $330 with shipping & tax about a year ago but, they no longer list them in stock. Crazy what the last year has done to stock and supply chains.

    B22B10AC-E15A-4C23-A5FA-16B6545085DC.jpeg
     
  3. Gearhed

    Gearhed Well-Known Member

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    Here's something that's odd: 97+ xj cherokees, Dakotas, durango's, and even some light duty 1500s got the 29 spline chrysler 8.25.
    However the liberty's, which came out a few years later, seem to be 27 spline, IIRC. They are also factory disc brake, but none are lsd as far as I know.
    My 5th Ave is going to be getting a 29 spline xj unit at some point soon, currently piling up the parts needed to do the swap (got plates and perches, need to get b body shocks and build a driveshaft)
     
  4. BudW

    BudW Moderator Staff Member

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    Are you going to get custom axles made (for the 29-spline carrier)?
     
  5. Gearhed

    Gearhed Well-Known Member

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    No, I've got a 7.25 in mine right now. being a Jeep guy, I got an entire xj 8.25 rear from a 2000. I'll be welding new perches on it and installing sometime this spring. From my measurements, it's roughly 1" wider overall compared to our cars, which shouldn't be an issue, it'll just bring the tire 1/2" further out on each side, which will help the looks IMO. The 29 spline rears are considered to be roughly the same strength as a ford 8.8, dana 44, and gm 8.5 10 bolt. They're pretty stout
     
  6. Duke5A

    Duke5A Well-Known Member

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    Is that a disc break axle? Don't forget the distribution block if it is. Inline Tube sells one for rear disc that is an exact replacement for the factory proportion valve. Bolts right into place. Another benefit of some of the parts under our hoods being GM pieces.
     
  7. Gearhed

    Gearhed Well-Known Member

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    No, mines drum brake. Rear disc was uncommon on xjs, usually a limited or cherokee country only.
     
  8. 88_AHB

    88_AHB Well-Known Member

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    Might be a little off topic but, I know a 29 spline would be considered a stronger axle than a 27 spline. Would you guys think this difference is worthwhile in durability and holding up to more HP? I know of course there's various factors that come into play with axle longevity such as driving conditions,gearing, power, weight etc. I've been contemplating upgrading my 8 1/4 to 29 spline inners (custom axles) or swap a 97-up axle out of a dakota etc. Just something that i've been thinking of before re gearing.
     
  9. Gearhed

    Gearhed Well-Known Member

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    You wouldn't want to use a dakota one, it's wider and a very weird 6 lug pattern. Took some accurate measurements, and the xj cherokee unit is actually within 1/4 inch of overall width of our cars, much closer than I originally thought. I'd almost be willing to bet that the 97-earlier xj unit is the same exact housing as our cars have. As far as strength, in the 4x4 world the 29 spline unit is considered to be as strong as the dana 44, and almost as strong as an 8.8 ford. I don't have an FMJ 8.25 to verify, but I would guess, based off my measurements of the 7.25 in my 5th, that if you put a 29 spline carrier in the FMJ housing, then you could probably use stock length xj axles with just a wheel bearing change. If someone ever has an axle shaft out of their stock 8.25, and wants to take some measurements, I'll measure my 29 spline
     
  10. Mikes5thAve

    Mikes5thAve Well-Known Member

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    If you already have 8 1/4 I wouldn't bother doing an upgrade just to get the 29 spline count unless you've had problems in the past. Stock 8 1/4 is pretty durable as is.
     
  11. LSM360

    LSM360 Well-Known Member

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    I agree