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3/8 or 1/4??

Discussion in 'The Garage' started by dleroy43, Sep 9, 2006.

  1. dleroy43

    dleroy43 1/2 ton status GMOTM Winner

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    I am figuring which parts to order for hydro assist, hoses/ fittings/ taps, and I am still confused of what size to use. If the ram uses -6 fitting then I should use 3/8 hose and a 3/8 tap into the gearbox correct? I found some that used 1/4 hose and/or taps as well. Does it really matter what size?

    :burb:
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    You want to use 1/4" NTP tap into the gear box and use a -6 fitting and 3/8" hoses. The -6 has an inside diameter of 3/8" roughly and so does the inside of a 1/4" NPT fitting.
     
  3. dleroy43

    dleroy43 1/2 ton status GMOTM Winner

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    Thanks :D
     
  4. sandawgk5

    sandawgk5 3/4 ton status

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    That is backwards. A 1/4" (2/8") fitting is smaller than 3/8" therefore the inside of a 1/4" fitting cannot be close to 3/8.

    For my ram I have -6 fittings and will be drilling and tapping to 3/8 NPT. I actually am only tapping the top cap as I purchased the end cap from JKWOffroad.

    Ira
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Well, i just went out and measured a fitting and 1/4" NPT fitting is .300" ID so .050" larger than 1/4" but .073 smaller than 3/8". Just remember that if you try to tap your box for 3/8" NPT you will probably be looking for another box as 1/4" NPT is VERY close to being too large if you tap in the common areas.
     
  6. sandawgk5

    sandawgk5 3/4 ton status

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    I am tapping the top cap not the box itself. I also have a new aluminum end cap that is tapped for 3/8 already:D .

    Ira
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The end cap will be fine but i would watch out tapping the top cap as i've read horror stories about the top cap exploding from being tapped there since there isn't much material in that area and the cap is fairly thin there, especially if you do the pump mods.
     
  8. sandawgk5

    sandawgk5 3/4 ton status

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    The top cap is over 1/4" thick in the thin spot. The problems I have heard is the people using the factory end cap and tapping that as it is basically sheet metal.:D If I do break a top cap I will figure a new way to do it.

    Ira
     
  9. ntsqd

    ntsqd 1/2 ton status

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    One of the vendors here posted a pic of a billet top cover they were making. Along with it was a pic of the end cap they were also making.

    Another point on the plumbing. Do not use the forged, tight 90* hose ends. Use the tube type swept 90*'s.
     
  10. az-k5

    az-k5 1/2 ton status

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    3/8 is huge for that purpose. I would recheck that. Alot of people mistake the OD to be the size when it is really the inner diameter of the fitting/line.

    A 3/8 NPT tap reqires you to drill a hole bigger than 1/2"
     
  11. dleroy43

    dleroy43 1/2 ton status GMOTM Winner

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    but I am tapping the box, not the caps :deal: . I could see how 3/8 would be too big for the box. So for the lines, 3/8 then?
     
  12. az-k5

    az-k5 1/2 ton status

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    Almost every kit you see uses 3/8 lines with -6 AN fittings and 1/4NPT holes in the box, caps, side or what ever.

    If you tap to 3/8NPT you will imidiately put a reducer in the system to step down to the hoses or the ram.
     
  13. sandawgk5

    sandawgk5 3/4 ton status

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    Not sure if I am understanding the concern but here is the cap I am using. It is tapped to 3/8 NPT and I am running 3/8NPT to -6 fittings to my hoses. My ram has -6 male fittings on it.

    Ira
     

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