Restoring/replacing differential and springs

Engine, Transmission & Driveline

  1. swisherred

    swisherred Senior Member

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    1967 Newport Custom.
    I want to change my gears from the 2.76 to 3.23 and swap springs, but I also have a hard time putting anything dirty back into the car when I take it out.
    I think if I'm going to go to the trouble of pulling the rear end to swap the springs and gears then I should also consider rebuilding it all....

    I have new green bearings installed already (prev-owner), but have never taken it apart. Is there anything I should look for or replace while I'm tearing this apart to clean and paint? Anything I should be aware of with these bearings so i don't damage something?

    I'm thinking center gasket, inner axle seals, outer brake plate gaskets and front spring bushings. Already have the rear bushing and shackles. I'm assuming the outer seals were replaced with the bearings.
     
    Last edited: Dec 5, 2019
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  2. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    I am not a big fan of the green bearings in a C-Body, they are a significantly lighter bearing than what came from the factory. Depending on the style of green bearing you have, some do not use an inner seal because the inner side of the bearing is open to expose the bearing to gear oil to lubricate it. The other style of green bearing is a sealed unit and does not really need an inner seal as long as some sealer is applied to the outer circumference of the bearing to seal it in the housing. The outer seal on a C-Body is an exclusion seal to keep brake dust and road wash out of the factory roller bearing. This seal is not needed with a green bearing as the outer part of the green bearing is always sealed.

    If you are changing gear ratios by changing third members, as long as an inspection does not show any pitting or scoring of the bearings or gears, go ahead and use the unit as is. If you are disassembling the third member to change the gear set, this would be a good time to rebuild it. A word of caution on rebuilding the third member, many of the bearing and seal kits advertised on E-Bay and elsewhere have ChiCom bearings and those are not worth putting in. Same is also true of the ChiCom seals. If you have never set up a rear end in this manner before, I suggest finding a knowledgeable person in your area to assist you as there are numerous ways to foul up the gear adjustments and trash a new gear set.

    Many C-Body housings and brake backing plates were not painted from the factory. If you are doing a factory correct restoration, the units should be left natural metal color and the appropriate grease pencil marks and paint dots should be reapplied. Otherwise, clean them up and paint what ever color you want.

    Dave
     
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  3. polara71

    polara71 Old Man with a Hat

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    Replace the springs !
     
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  4. swisherred

    swisherred Senior Member

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    That is very good information. I do have another lower mileage 8.75 with axles and very nice original bearings...maybe I should consider using that instead in order to retain the better bearings. The axle seals on that one didnt leak. I intended on swapping 3rd members as a whole. The one I have looks to be in good shape...almost zero slop in the pinion to ring mesh. No visible wear. Im also not doing a factory resto...just fixing everything and making new...not necessarily original. I will look at cleaning up my extra one, installing the new chunk in that and swapping my brake plates over to it as they have all new brakes.
     
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  5. Davea Lux

    Davea Lux Old Man with a Hat FCBO Gold Member

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    Properly set up and adjusted, the factory roller bearings are bullet proof and are usually good for 100k or better. Replace the inner seal while you have the axles out and repack the roller bearings and you should be good to go. FSM gives details on how to adjust the axle bearings.

    Dave
     
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  6. swisherred

    swisherred Senior Member

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    My current axle has 105k...and is sloppy engaging. The other is around 60k. Unknown on the center chunk as its coming from another rear. I will order a gasket, inner seals and new outer dust seals...and follow the fsm on the adjustment. Degrease, clean and paint. Maybe powder coat the brake plates. We powder at work.
     
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  7. '69FuryIIIConvertible

    '69FuryIIIConvertible Senior Member FCBO Gold Member

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    On the subject of colours and paint, I've disassembled quite a few and found a mixture, 79k mile all original unit was unpainted, yet the 60k mile unit from another car was semi gloss black and the gearset was red oxide...
     
  8. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    I never bother with the 3rd member gasket. Ultra black permatex and done, same with those dumb foam gaskets on the backing plates. Definitely replace the inner seals and repack the bearings.
     
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  9. CudaChick1968

    CudaChick1968 The Mistress of Metal FCBO Vendor

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    Be sure to outgas everything for at least a couple three hours to pull all the oils and contaminants out first before blasting it.
     
  10. swisherred

    swisherred Senior Member

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    definitely...thank you. contemplating doing the axle housing as well, but dont know that I want to because of the chance of contamination from the oils...and dont think I want to bring it up to temps high enough to burn it all out.
     
  11. CudaChick1968

    CudaChick1968 The Mistress of Metal FCBO Vendor

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    I've done a bunch of rear end housings and they take over an hour to heat up but the results are worth it. Just hang it vertically and put a sheet of foil on the oven floor to catch the outgassing grunge that oozes out. You won't have to fight it later coming through your powder.
     
  12. swisherred

    swisherred Senior Member

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    I wish I could...our oven is only 48" tall and 48" wide....but 10ft long...maybe hang at an angle....