Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

m1009 gearing questions

Discussion in '1982-Present GM Diesel' started by fourwheelerjeff, Apr 25, 2007.

  1. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

    Joined:
    Nov 16, 2001
    Posts:
    3,419
    Likes Received:
    6
    Location:
    meadow, tx; in the boonies
    i have an m1009 that i was going to sell, but looks like i may keep it.
    if i plan on driving this to the trails every once in a while, on some 36 inch swampers, what would be a good gear ratio?
    leave the 3.08's in it for 2012.3 rpm's
    put some 3.42's in it for 2234.4 rpm's
    put some 3.73's in it for 2436.9 rpm's
    put some 4.10's in it for 2678.7 rpm's

    thanks
    jeff
     
  2. imiceman44

    imiceman44 1 ton status

    Joined:
    Aug 5, 2002
    Posts:
    15,160
    Likes Received:
    1
    Location:
    Sacramento, CA
    If you have the th400 in front of your 208, I'd say keep the 3.08 for now, see how it goes.
    I know the engine will ike the low RPM's at highway speed, you just need o see if it has the pick up and go then you're golden.
    I did that with my diesel but I had an SM465 so when i needed more go, I would start in Granny low, but most of the times starting in 2 was jut fine.:D
    And I had 35" tires.
     
  3. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

    Joined:
    Nov 16, 2001
    Posts:
    3,419
    Likes Received:
    6
    Location:
    meadow, tx; in the boonies
    yes, i have the turbo 400 and will be driving it to wheel. i was thinking 3.42's might be a good compromise. supposed to look at some axles today that are rebuilt.
     
  4. jp0863

    jp0863 1/2 ton status Premium Member

    Joined:
    Aug 15, 2004
    Posts:
    566
    Likes Received:
    0
    Location:
    clovis, ca
    i have 4.10's with 35's and it seems a little too low geared for the highway, but works well for foothill's driving. in the mountains on steep grades it just doesnt make enough power to begin with so not sure gearing is as much an issue. when i had the 3.08's and 31's or the 4.10's with 35's it didnt matter... just sloooooow as heck going up grades
     
  5. imiceman44

    imiceman44 1 ton status

    Joined:
    Aug 5, 2002
    Posts:
    15,160
    Likes Received:
    1
    Location:
    Sacramento, CA
    Just as a comparison:
    I have a wagoneer with the 360 V8/th400 and 3.54 gears with 35" tires.
    It drives fine but I have to shift manually to help it accelerate, the diesel will do better with better low RPM torque, on the highway speeds I never had any problem keeping up with traffic.
    :D
     
  6. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

    Joined:
    Nov 16, 2001
    Posts:
    3,419
    Likes Received:
    6
    Location:
    meadow, tx; in the boonies
    i have settled on the 3.73's i believe. tires will be 38 inch swamper radials
     
  7. rajincajingt

    rajincajingt Registered Member

    Joined:
    Nov 13, 2005
    Posts:
    5
    Likes Received:
    0
    Location:
    baton rouge
    this is my first post here so please be gentle, but im looking into a CUCV truck for a temporary tow rig. For some good hwy rpms, 60-70mph, you will need some 3.55s, 38.5"??? that sounds crazy to me.

    i read that the sweet spot is 1850-2000 for mpg and 2500 for torque, correct?

    and just a stupid question, why is that when calculating a gear ratio with an auto vs manual, the rpms are higher in the auto? is the torque converter eating some of that or jsut the tranny itself??
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,180
    Likes Received:
    1,388
    Location:
    E-town baby!
    If you're planning to tow i'd gear deeper, or go with not such a large tire. If you're not towing and want economy then aim for the 1800-2000 range on the freeway.

    Unless the auto has a lock-up convertor the auto will have a little bit of slip even at highway speed. It's usually about 4-6% depending on the torque convertor, tranny, gearing and rpms...

    Rene
     

Share This Page