Gearing question

Discussion in '60-Series Wagons' started by EarthX, Feb 20, 2009.

  1. EarthX

    EarthX Owner of Earth Exploration Technologies

    Messages:
    904
    Likes Received:
    384
    Joined:
    Mar 6, 2005
    Location:
    Lake Arrowhead
    After driving around on my 38s I've decided it's time to re-gear. Now all this gearing stuff is a little over my head right now. I hoping someone will help me calculate what gear I need.
    The rig is now set up like this:

    fj80 axles with 4:11 thirds
    stock slit case
    4l60e tranny
    38" tires

    With the 38s I think I'm feeling the tranny slip while driving up hill while under hard power.
    I bolted up some 275/70/16 tires I had sitting around and the difference is amazing! Until I re-gear I may run these, even though it looks ridiculous.
    What would be the equivalent of the 275/70 in r&p gears?

    Someone educate me.:cheers:
     
  2. Dirtgypsy

    Dirtgypsy

    Messages:
    2,414
    Likes Received:
    66
    Joined:
    May 27, 2006
    Location:
    Dundee, Oregon
  3. EarthX

    EarthX Owner of Earth Exploration Technologies

    Messages:
    904
    Likes Received:
    384
    Joined:
    Mar 6, 2005
    Location:
    Lake Arrowhead
    Perfect. Thanks for the link.
    I think you're right, 4.88s seem to be the sweet spot.
     
  4. EarthX

    EarthX Owner of Earth Exploration Technologies

    Messages:
    904
    Likes Received:
    384
    Joined:
    Mar 6, 2005
    Location:
    Lake Arrowhead
    Ok, after messing around with that calculator a bit more, Im having a had time deciding which would work better; 4.88s or 5.29s. At 70 mph, 4.88s should put me right around 2114 rpms. 5.29s around 2292. Not a whole lot a difference. Im thinking that the 5.29s might make up for that slightly higher rpm with great low range performance. Any thoughts? Does those rpms seem to high for highway use?
     
  5. brokenparts

    brokenparts

    Messages:
    4,046
    Likes Received:
    96
    Joined:
    Apr 4, 2006
    Location:
    Hillsboro, OR
    you start to sacrifice some strength once you move past 4:56. You also may need to ground down your ring on a ratio higher than 4:56 with and ARB.
     
  6. EarthX

    EarthX Owner of Earth Exploration Technologies

    Messages:
    904
    Likes Received:
    384
    Joined:
    Mar 6, 2005
    Location:
    Lake Arrowhead
    Ive heard mixed opinions on the strength of 4.65's. I wont be going higher than that and whatever I choose will be cryo treaded, Im not worried about the strength. Also Im runner factory elockers so no ARB for me.
     
  7. NocalFJ60

    NocalFJ60

    Messages:
    3,550
    Media:
    6
    Albums:
    1
    Likes Received:
    6
    Joined:
    Aug 2, 2004
    Location:
    San Francisco Bay Area
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.