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TC up grade vs axle gear up grade

Discussion in 'Jeep CJ Builds' started by pastor scott, Oct 9, 2018.

  1. Oct 9, 2018 at 7:32 PM
    #1
    pastor scott

    pastor scott [OP] Active Member

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    So here is the question
    Can I get away with 3.50 axle ratio by modding my dana 20 transfer case to a teraflex low gear mod ?

    Also what is the lowest tC gear mod they sell
    Will be running 33 Inc tire 304 V8 3 speed manual .this is strictly an off road jeep .Will the teraflex gear reduction be enough for crawling.

    Thanks guys. Your wisdom is helping me allot

    Ps Scott
     
  2. Oct 10, 2018 at 6:02 AM
    #2
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
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    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    If your running 33s, the 3.5 ratio on the road is decent. The Dana 20 low gear is a 3.7:1. It is the only low gear ratio that I have seen on the market.
     
  3. Oct 10, 2018 at 6:28 AM
    #3
    pastor scott

    pastor scott [OP] Active Member

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    With going to this TC upgrade what would my axle rations in theory be for you math guys.
     
  4. Oct 11, 2018 at 12:24 AM
    #4
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
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    Member:
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    Messages:
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    Gender:
    Male
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    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Not sure what you mean. Your axle ratio doesn't change unless you regear the axles. Maybe you are asking about "crawl ratio"? Your T150 3speed Tranny is going to kill your crawl ratio because of it's very high first gear. Go here for starters. . . http://4lo.com/calc/gearratio.php Any crawl ratio over 60 is supposed to be excellent, but I have never had one that High. I am currently around 45 and happy with it.
     
    Last edited: Oct 11, 2018
  5. Oct 11, 2018 at 7:03 AM
    #5
    pastor scott

    pastor scott [OP] Active Member

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    Thanks
    Got to get my math hat on . Lol
    Wow
    Yes that's what I kinda wanted to know. To know if sticking with stock 3.50 axle Gears and upgrading my transfer case to the Tera low on 33 in tires would be OK for off road rock crawling .

    Ps Scott
     
  6. Oct 11, 2018 at 7:25 AM
    #6
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
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    Member:
    #317
    Messages:
    1,945
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    I say start there and if you find that you need more, regear. If you regear 4.10s is good for 33s, but I would consider 4.56 gears if not driven on the HW too much and you are mainly building this for offroad.
     
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