28 To 31 Spline

Discussion in 'SN95 4.6L Mustang Tech' started by usaf_branham, Jan 5, 2014.


  1. usaf_branham

    usaf_branham Member

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    I have the stock 28 spline diff. Can I buy a 31 spline rebuild kit and replace the 28 spline spring with the supplied 31 spline spring, and get some 31 spline moser axles? Or am I stuck buying a 31 spline diff in order to use 31 spline axles? I would think that if I swapped the clutches and disc's from 28 to 31, and use the bigger spring, I could save a few hundred bucks and reuse the stock differential, but I am not entirely sure if that would work or not. Thanks.
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  2. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor Admin Dude

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    You need the axles (of course) and complete 31 spline traction lock.

    [​IMG]

    You can get them from the junkyard if you can't find one on-line at a decent price.

    Someone chime in if I'm missing anything: @Mustang5L5
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  3. Bob Hughes

    Bob Hughes Member

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    No that's it minus install kit. I swapped mine last year to 31-splines pretty cut and dry. You can get the whole trac loc units from am pretty reasonably priced
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  4. sneaky98gt

    sneaky98gt Mustang Master

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    Gotta have a 31 spline carrier.

    Get rear-end stuff from Tousley Ford if you want to really save some money.

    31 spine Cobra/GT500 diff: $215 https://parts.autonationfordwhitebe...fo&PartID=957827&siteid=214771&catalogid=5684

    Full install kit, including GT500 pinion bearings, carrier bearings, axle bearings, all seals, etc. i.e. EVERYTHING thing you need to completely rebuild the rear-end: $90 https://parts.autonationfordwhitebe...fo&PartID=498790&siteid=214771&catalogid=5684

    (you can get one for $10 cheaper without axle seals and bearings)

    I'm assuming you aren't replacing the gears. If you were, those are around $120. https://parts.autonationfordwhitebe...o&PartID=1071356&siteid=214771&catalogid=5684

    So you can build the rear end for $305 + axles + gear oil. You can find axles often on online classifieds if you look around. I picked up a brand new set for $150 from the Corral.

    Pro-tip. DO NOT use the gasket that comes in this kits for the differential. It WILL leak. Use gray RTV instead.
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  5. usaf_branham

    usaf_branham Member

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    Thanks sneaky. Yeah I'm keeping the gears, and I'll re-use the bearings since I've already swapped them twice and the have less than 5k on them (unless the races are scored).

    I see AM has some 31 spline moser axles... How hard is it to swap the abs ring from the stock axles to the new ones? Do they press off? I didn't pay attention when I swapped to 3.73's.

    That sucks that I can't just throw the 31 spline rebuild kit into a 28 spline trac-lok. I figured the only difference would have been the clutches and metal rings inside the diff. When I replaced the stock clutches with the carbon fiber kit, I don't recall the axles physically splined in to the diff it's self. That's been years ago tho.
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  6. usaf_branham

    usaf_branham Member

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    I used black RTV and haven't had any leaks. Do I suppose grey is better?
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