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When putting Dana 18 gears in a Dana 20

Discussion in 'Early CJ-5 and CJ-6 Tech' started by DanStew, Jan 19, 2005.

  1. Jan 19, 2005
    DanStew

    DanStew Incorrigible. Staff Member Sponsor

    Lexington, South...
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    The the Dana 20 case be quiter still?? I know the 20 originally was the "quiet" transfercase as compared to th Dana 18, but not sure it is because of the way the gears are cut or that all the gears moved in the dana 18 becuase of the offset outputs.
     
  2. Jan 19, 2005
    rocnrol

    rocnrol Member

    calgary alberta,...
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    hey danstew........ i did this mod to my 20 last year. i havent noteced any change in noise at all. i dont recall seeing any difference in the way the gears were cut to make a change in noise...... i do know that there is a diference between the 300 and the 20.

    if your going to do this, look for a case from a "j" truck as their cases suposedly need less grinding to clear the bronco slider. :D

    these are the gear #'s you need:
    from d18.... input gear....spicer # 18 8 23, tooth count 29
    high range out put shaft gear... spicer # 18 8 23, tooth count 29

    intermediate gear.... spicer # 18 5 9 , tooth count... 18 straight and 39 helical

    lower sliding gear ..... spicer # 18 8 22... tooth count 33

    and from the bronco 20.. upper sliding gear... spicer # 18 8 58... tooth count 33 ;)
     
  3. Jan 19, 2005
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    The high range gear you need is an 18-8-24, not 23. The input gear is an 18--8-23 as already noted. The reason your transfer case is noisy is because you are using the wrong Bronco slider. The one you need is an 18-8-37 from the early Bronco 6 cylinder transfer case. The 18-8-58 is from the later Bronco 20 and is the wrong one as it has a different pitch to the gear, there are two versions of this case. That's what makes the Bronco gear so difficult to find used. I believe Jack O'Brien is making these new. There was a web site linked to Off-road.com that had the information that you've posted, and it is wrong. I tried contacting those folks years ago with the correct info and It was acknowledged I was correct, but the site went unchanged. How do I know this? One, I've done at least 50 of these conversions, and two, I know the guy who pioneered this conversion back in the early '70's, Ed Holbrook.
    It's pretty normal for the 20 to be quieter than an 18 even though you are using mostly 18 gears Dan as the power flow through the transfer case is now different due to the different location of the rear output shaft. By the way, do a search on this forum, we covered this a while back pretty extensively. Nickmil.
     
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  4. Jan 19, 2005
    DanStew

    DanStew Incorrigible. Staff Member Sponsor

    Lexington, South...
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    I was going throguh the old posts last night. Actually got pretty confused because i found differnt numbers psots as what i needed. As far as i was reading it looked like i jsut needed the Complete Dana 18 gears to throw in there and just that bronco gear. My eyes went cross reading it all. Even got more confused, i will need a 6 spline, 29 tooth gear to mate teh Tcase to the T18 i am using. So now as i go back and think bout it. I guess i am changing the intermediate geat and high and low gears to the Dana 18 gears, and keeping the inptu and output shafts and main shaft from the dana 20. I havnt taken the 20 apart yet so i will have to go at it to see what i have and need. But those part nubmers do help.
     
  5. Jan 19, 2005
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    Here is a list of what is needed to make a 2.46-1 low range model 20:

    1) 18-8-23, 29 tooth 6 spline input gear
    2) 18-8-22 gear
    3) 18-8-24 gear
    4) 18-5-9 intermediate gear
    5) 18-8-37 slider gear from EARLY Bronco 20

    The rest is bolt up except you may have to grind some on the case (most do) to clear the slider gear. Sometimes you have to grind the pan rail/opening to get the intermediate gear in also depending on which assembly order you go in. I'd recommend checking it so down the road if there is a problem you don't have to disassemble the whole transfer case to get the intermediate gear out. Nickmil.
     
  6. Jan 19, 2005
    DanStew

    DanStew Incorrigible. Staff Member Sponsor

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    OOOOOHHHH.. OK, i understand now. I thoguht the bronco gear was the input gear. OK, so the bronco gear is something else. I had it in my head that it was the input gear for some reason, then last ngiht i got to counting splines and teeth and i realized i didnt need a differnt input gear, the one i have is going to work. I will have ot do all this with the Dana 18 apart, so it will ahve to wait a bit. Also check my pandoras box of gear parts, may have some in there :)

    Thanks!!!
     
  7. Jan 19, 2005
    rocnrol

    rocnrol Member

    calgary alberta,...
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    :oops: :oops: i had just gotten out of bed ;)

    nicmill, truthfully i dont remember the number of the bronco gear that i used......but i do remember that the one i found in the pile of bronco crap in my buddys garage did not have the number that i have in my post, but every thing about it matched up.... so maybe i did get the right one :? it isint any noisyer then it was befor and it works just fine.....dono.

    i ended up buying all my 18 gears new as i couldnt find any used, came out to $200 from the local shop, not bad i thought. i have it behind a t-18a and the difference off-road is trully awsome :D this was one of the top mods that i did to my jeep.
     
  8. Jan 21, 2005
    nickmil

    nickmil In mothballs. Sponsor

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    COOL! :D Sorry if I seemed a little brusk. Have been sick and time has been very limited. Some people have tried the 18-8-58 gear and it will work, for a while, then it ends up grinding everything up inside. It's pretty noisy in the meantime. If yours has been together and used for a while then you probably ended up with the correct gear, the 18-8-37. Have a good weekend! :stout: Nickmil.
     
  9. Dec 5, 2018
    Tomellen

    Tomellen Member

    Ticonderoga, NY
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    nicmill, u still active on the forum
     
  10. Dec 5, 2018
    homersdog

    homersdog Tulsa, Ok Sponsor

    Tulsa, OK
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    He still chimes in occasionally. You can send him a PM.
     
  11. Dec 7, 2018
    nickmil

    nickmil In mothballs. Sponsor

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    The slider you need is the 18-8-37, NOT the 18-8-58. That's why yours is noisy, wrong gear. I submitted this info to Off-road.com about 18 years ago and they agreed. And still posted the wrong info. I've been doing this conversion for close to 25 years professionally.

    Just realized how old this thread is and that I had already posted here :oops:
     
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  12. Dec 7, 2018
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    Sometimes but mostly not. I don't seem to get notifications so I only know if I get a message if I log in. Not often any more.
     

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