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D18 4 to 1 gears

Discussion in 'Early CJ5 and CJ6 Tech' started by jzeber, Dec 18, 2004.

  1. Dec 18, 2004
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    Nov 15, 2003
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    3,326
    Hi All,
    Just wondering if anyone here has done the "Tera Low 4to1" kit on a Dana 18? I have read that you can't use the overdrive if you use this kit. Just wondering and as always any help is appreciated. I am currently running the stock D18, SM465 and 4.88 gears. My current crawl ratio is 76:1. Theoretically with the Tera Low it would be around 107:1
    Thanks,
    Jeff Z
     
    jzeber, Dec 18, 2004
    #1
  2. Dec 18, 2004
    Project71-5

    Project71-5 BACON

    Gypsum, CO
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    Sep 24, 2002
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    897
    I think that the case needs to be machined inside to get the needed clearance for the gears. I might be getting the Teralow kit confused with the Jack O'Brien 6:1 kit though.
     
    Project71-5, Dec 18, 2004
    #2
  3. Dec 18, 2004
    Jeepenstein

    Jeepenstein Me like Jeep.. 2024 Sponsor

    North Central FL
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    Jun 15, 2003
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    I dunno bout the 4:1.. maybe out west where there is no mud it'd be ok but here you need to generate some wheel speed sometimes, 2.43 is ok with me and with a crawl ratio that loooow is an axle breaking machine!

    BUBBA
     
    Jeepenstein, Dec 18, 2004
    #3
  4. Dec 18, 2004
    willysnut

    willysnut Banned

    Newnan, Ga.
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    Oct 8, 2003
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    654
    I think the tera low is 3.15 to 1.
     
    willysnut, Dec 18, 2004
    #4
  5. Dec 18, 2004
    66cj5

    66cj5 Jeep with no name

    NorthWest Indiana
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    Sep 10, 2003
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    2,084
    herm has an od kit for both the terra low and o'brian kits.
     
    66cj5, Dec 18, 2004
    #5
  6. Dec 18, 2004
    matt koch

    matt koch Member

    fort collins co.
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    Oct 24, 2004
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    you can call advance adapters at 1-800-350-2223 . talk to steven davis he can tell if you can use your overdrive or not .
     
    matt koch, Dec 18, 2004
    #6
  7. Dec 20, 2004
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    Sep 20, 2002
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    TeraLow's kit is 3.15:1 for the D18. They do have 4:1 kits for other tcases, but not the D18.

    The case does need to be machined if you go with Jack O'Brien's gearsets, which are 4:1 and maybe even lower for the D18. Jack's gears are expensive, but they are of the highest quality. As Don said above, Jack can answer all of your questions.
     
    lynn, Dec 20, 2004
    #7
  8. Dec 21, 2004
    lynn

    lynn Time machine / Early CJ5 HR Rep Staff Member

    Huntingdon PA
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    Sep 20, 2002
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    Erik
    :shock:
    That's interesting, I had not heard of the Orion tcase before. I did a search over on POR. Apparently AA has been making them in "kit" form; for TLCs. Sounds like they're going to market a fully assembled D18 replacement in 4:1, but nothing on their website yet...
     
    lynn, Dec 21, 2004
    #8
  9. Dec 21, 2004
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    Nov 15, 2003
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    Sooooo, is anyone out there running the O'Brien or Tera kit? It may seem like overkill but since installing the SM465 trans I use the go pedal a lot less. I usually do a lot of rockcrawling around here. I figure at my current 78:1 it is a lot more torque but a lot less speed. If I go with the Tera kit at 3.15:1 it will give me a final ratio of just under 100:1. Besides I am running a 231 V-6 so lots of low end grunt but not a lot of ponies, seems to work pretty good for me.
    Jeff Z
     
    jzeber, Dec 21, 2004
    #9
  10. Dec 21, 2004
    mb82

    mb82 I feel great!

    Charlottesville Va
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    Mar 17, 2003
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    jeff i considered a terra low kit along with my t-18 but then i figured why spend the money. 5.38s + an overdrive will be all that i need. now that orion case that interests me.
     
    mb82, Dec 21, 2004
    #10
  11. Dec 21, 2004
    53Flattie

    53Flattie Intigator

    Easley, SC
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    Sep 23, 2002
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    A friend of mine has the Tera Low kit in his M38. He used a Dana 20 case, rather than grinding the inside of the Dana 18. He hasn't put too many miles on it, but I will say that it's quiet, the parts were high quality, and the installation was straight-forward.
     
    53Flattie, Dec 21, 2004
    #11
  12. Dec 22, 2004
    ScottP66CJ

    ScottP66CJ Member

    SoCal
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    Oct 16, 2002
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    Advance does make a gear set for the overdrive in the 3.15:1.
     
    ScottP66CJ, Dec 22, 2004
    #12
  13. Dec 22, 2004
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    Thanks for all of the info. I just picked up a spare t-case and I am kicking around the idea of using one of the gear sets available. Sounds like Herm may be the way to go and still maintain the OD. I haven't heard of the O'Brien set but a true 4:1 sounds like the best bet....decisions, decisions, decisions....
     
    jzeber, Dec 22, 2004
    #13
  14. Dec 22, 2004
    mb82

    mb82 I feel great!

    Charlottesville Va
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    i thought the obrien was a 5.38/1 setup? or am i thinking of a zuki
     
    mb82, Dec 22, 2004
    #14
  15. Dec 22, 2004
    jzeber

    jzeber Well-Known Member 2022 Sponsor

    Morgan Hill, Ca
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    I used to have a magazine around that walked through the Tera Low kit. Any good websites for any of these kits regarding installation?
    Thanks
     
    jzeber, Dec 22, 2004
    #15
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