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Front and rear diff/transfer drain and fill

Discussion in 'Tech Discussion' started by MisterB, Sep 29, 2019.

  1. MisterB

    MisterB Full Access Member

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    What front diff do I have? [​IMG]

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  2. MisterB

    MisterB Full Access Member

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    Can you tell from this Pic which transfer case I have? [​IMG]

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  3. MisterB

    MisterB Full Access Member

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    Thanks for the info. Does this look like the one I have? [​IMG]

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  4. MisterB

    MisterB Full Access Member

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    As for the transfer case, I have no idea when I compare my Pic to the link you shared. Any ideas?

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  5. Craig 85

    Craig 85 Full Access Member

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    Looks like a 14 bolt FF rear, 10 bolt GM front axle and a NP-205 transfer case. The rear brakes look to be the 13" x 2.5" drums.
     
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  6. MisterB

    MisterB Full Access Member

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    What weight gear oil should I run in the front? Any idea general capacity?

    How about the NP-205, as far as gear oil/fluid?

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  7. MisterB

    MisterB Full Access Member

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    Is that 75w-140 the right one for the front diff as well?

    What about the transfer case?

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  8. ali_c20

    ali_c20 Full Access Member

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    Early manuals say 80-90 gear oil. There are later manuals that say atf. I use 80-90 gear oil in my 205 behind a th350. Running without any issues since 6 years.
     
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  9. MisterB

    MisterB Full Access Member

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    Do I need to change any gaskets when draining and filling the transfer case? I know I need a new gasket for the front diff and one for the rear, but not sure about the transfer case

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  10. ali_c20

    ali_c20 Full Access Member

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  11. MisterB

    MisterB Full Access Member

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    Looks like the service manual for an 80 4x4 says to use motor oil. I figured the service manual would be much more specific about what transfer case and differentials I have, but it isn't. I'll post screen grabs below

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  12. MisterB

    MisterB Full Access Member

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    Sounds like front and rear differentials call for the same fluid type, although I'll likely upgrade to the thicker fluid recommended here. Sounds like I'll need about 10 quarts total for both?

    Transfer case calls for motor oil. Any idea how much? [​IMG][​IMG][​IMG][​IMG][​IMG]

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  13. ali_c20

    ali_c20 Full Access Member

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    The np203 (chain driven) needs engine oil. The chain needs thinner oil to lubricate the links and there is a pump in the tailshaft that lubrictaes the rear bearing. The 205 is gear driven. I don't think you could hurt the 205 when using engine oil or atf. I got my 205 from offroad design and they told me to use gear oil. Works since 6 years. It takes ~ 2.5 quarts iirc.
     
  14. Rick Dobbins

    Rick Dobbins Junior Member

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    Yes Eric I would. And we have the same rear end set up!
     
  15. MisterB

    MisterB Full Access Member

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    Got the rear diff drained and filled. I went with full synthetic gear oil in 75w140. Cleaned and degreaser the cover and bolts, and then painted the cover and bolt heads with some Rustoleum black spray on bed liner.

    I also drained and filled the transfer case. I used motor oil, since that's what the factory calls for, and I already had some. Ended up using Valvoline 5w30 Max Life synthetic blend. Full synthetic 75w-140 Lucas gear oil already costs a small fortune, so it was nice to be able to use some oil I already had.

    Next up is the front diff. I'll do that another day. Need to buy more 75w-140 gear oil. [​IMG]

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