1. Davesmopar

    Davesmopar Well-Known Member

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    I'm about to start building this 8 3/4 rear end with a 489 case oh, I am going to go with a crush sleeve Eliminator kit + 1350 yoke...

    I am looking for the assembly specs with old bearings as well as new bearings....
     
    Last edited: Nov 3, 2019
  2. XfbodyX

    XfbodyX Well-Known Member

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    If your getting your parts from the Dr. he would have them for you
     
  3. Davesmopar

    Davesmopar Well-Known Member

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    Yes but I do have a 323 sure grip I can put in there until I can afford to build the rear end that I want
     
  4. XfbodyX

    XfbodyX Well-Known Member

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    Thought YOUR car had 4:56-s in it :0
     
  5. Davesmopar

    Davesmopar Well-Known Member

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    Maybe... lol

    It is at a friend garage now
     
  6. Davesmopar

    Davesmopar Well-Known Member

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    l looked at the ring gear last night don't see anything wrong with it, but it does have a 1973 date code on it. Now when I try to turn the yoke a little bit of a rust came out from the pinion seal area so I think I've obviously have a front pinion bearing gone
     
  7. XfbodyX

    XfbodyX Well-Known Member

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    Just run it, it will free up.....not.
     
  8. BudW

    BudW Moderator Staff Member

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    If your front pinion bearing had gone out, there would be noticeable up/down play on the differential yoke (no matter the size or who made the differential). Usually when this happens, there is also noticeable recent leakage from the pinion seal.

    Some rust in that area doesn’t mean much.
    BudW
     
  9. Davesmopar

    Davesmopar Well-Known Member

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    I don't think the bearings bad as far as being loose I think it's bad when it's been sitting out in the open and just got water in it and rusted.

    I pulled this thing out of a personal junk yards probably been sitting out in the open elements for 15 + years.


    Does anybody have specs?
     
  10. BudW

    BudW Moderator Staff Member

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    These are from my 1970 Chrysler FSM (Factory Service Manual), for 489 case

    Pinion Bearing Pre-Load Torque (Seal Removed) – 20-35 Inch-pounds (new bearings). Old bearings are “10 Inch-pounds over the original” – whatever that means exactly. Note: this reading can only be accurate, if differential is in an upright position (per the FSM).
    Ring Gear Runout – 0.005” max.
    Differential Case Runout – 0.003” max
    Ring Gear Back Lash – 0.006 to 0.008”
    Side Gear Clearance (with Gauge) – 0.001 to 0.012”
    Wheel Bearing End Play – 0.008” to 0.018”

    Lube Capacity- 4.4 Pints of 90w (additive might be needed depending on Limited-Slip, if applicable).

    Bolt Torque:
    Differential Bearing Cap – 90 foot-pounds
    Ring Gear (Left Hand Thread) – 55 foot-pounds
    Side Bearing Adjuster Lock Bolt – 15-20 foot-pounds
    Pinion Flange Nut – 170 foot-pounds (Min)
    Carrier to Housing – 45 foot-pounds
    Axle Shaft Retainer – 35 foot-pounds
    Propeller Shaft – 15 foot-pounds
    Spring Clip (U-Bolts) – 45 foot-pounds
    Lug Nuts – 65 foot-pounds
    Shock Nuts (Lower) – 50 foot-pounds (if using the older style shock plates (which is a huge improvement over the ISO-Clamp system that FMJ's all use).

    All of the above data is from my '70 Chrysler (C-body) FSM.
    BudW
     
  11. BudW

    BudW Moderator Staff Member

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    Note: If there are any rust pitting on the ring or pinion gear set – the differential will make noise above what one normally makes. The severity of noise will be equal to the extent of rust pitting.
    There is nothing wrong with using a rusty ring/pinion gear set – if you understand that noise might be an issue.

    Rusty bearings are a different issue. Always change all bearings if there are any signs of rust, pitting, discoloration or streaks on bearings or races. Bearings are relatively cheap to replace. A small defect in a bearing will snowball to a big problem in no time, damaging the other bearings just as quick (from metal flacking off original bearing).


    My last thought is I will not reuse a non-Limited Slip carrier/case on a personal rebuild or for any of my friends/family. The only thing a non-Limited Slip carrier/case is good for is a door stop or boat anchor.

    Nothing wrong with using a used Limited Slip – for most can be rebuilt (but not all).
    BudW
     
  12. Davesmopar

    Davesmopar Well-Known Member

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    Now that is what I was looking for, thank you very much. The third member has a Borg Warner spin resistant cone Style Sure Grip unit, which from what I understand is not rebuildable
     
  13. BudW

    BudW Moderator Staff Member

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    For the 8¾” differential, there are four different limited slip versions:
    The Clutch-type. When the differential side gears are in use (on turns or when tires slip), the side gear shafts push against and slide on the “V” groves, which engage the clutches. The more slippage, the more pressure engaged to disks.
    8.75 Clutch LS.jpg

    The Cone-type (what you have). This one is made by Auburn, but yours will be similar. It uses springs to push the cones into the case iron case.
    8.75 Cone LS.jpg

    Eaton Tru-Trac. It uses a series of gears to provide the locking.
    8.75 TruTrac LS.jpg

    The “open” differential and not worth reinstalling into any vehicle (ie: NO limited slip).
    8.25 Open Carrier.jpg


    8¼” and 7¼” limited slip differentials are similar but not look exact. The “V” or the springs will be the same, though. Unless a recent changed, the Eaton Tru-Trac is not available for FMJ’s (which is a shame).

    All FMJ’s that had a factory limited slip installed are of the Cone-type.

    The Cone-type and Eaton Tru-Trac can use normal lube. The Clutch-type needs a friction modifier added to the diff lube or you will have clutch chatter every turn you take.

    Nothing wrong with using a Cone-type carrier – just as long as it is holding. If it is shot, then someone has a new doorstop or boat anchor. When both rear wheels are off ground (and car is in park), take either rear tire and turn it. The tire shouldn’t turn or can if you take excessive measures to do so.
    BudW
     
  14. Gator

    Gator Well-Known Member

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    The cone style carriers are rebuildable dr diff sells shim kits for them ,they have to be machined down .03 down .I just had a 489 cone style rebuilt buy my machinist there's also a thread on abodies about how to rebuild them..great info guys