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Highway gears

Discussion in '1982-Present GM Diesel' started by u2slow, Dec 5, 2002.

  1. u2slow

    u2slow 1/2 ton status

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    Anyone running ratios like 3.73, 3.42, or 3.21 together with a TH400 on their diesel?

    My Burb has 4.10's; I have a spare 3.73; am considering 3.42 (but can't find any); and a few guys I know have 3.21's for sale.

    It just the grocery-getter, so economy is the primary goal - but I don't want to make it undriveable.
     
  2. imiceman44

    imiceman44 1 ton status

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    Grocery getter, that's fine, btu you left out the most important detail:
    tire size.
    I run 3.08 with 35" tires with an SM465 in my diesel blazer, and 3.54 with 35" tires with a TH400 in my Full size Jeep Wagoneer.
    They both drive fine on highway, the diesel makes it perfect for wheeling too, the Jeep needs a little more to be better off road.
     
  3. u2slow

    u2slow 1/2 ton status

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    Oh yeah... tires /forums/images/graemlins/blush.gif

    It's 2wd, and I have 33's on it just for economy's sake. Stock 31's are just fine too.

    After a little math, it looks like 3.54/35's are about the same as 3.21/31's. I presume your Wagoneer is a gasser, so a diesel should even be a bit nicer, or at least compensate for my heavier Burb.

    Thanks!
     
  4. imiceman44

    imiceman44 1 ton status

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    Yep the Wag is a gasser, actually you can see more details in my profile. /forums/images/graemlins/deal.gif
     
  5. DieselDan

    DieselDan 1/2 ton status

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    for comparison the M1009 (K5) CUCV runs 3.08 on 31X10.5 (TH400 and 6.2 of course). /forums/images/graemlins/wink.gif
     
  6. arveetek

    arveetek 1/2 ton status

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    My opinion is keep your gears and tires and get a 700R4 tranny. The 4.10's are great for off the line acceleration, towing, and everyday drivability. The 700's overdrive keeps the rpm's down on the highway. I average 18.5 mpg on the road with my 4.10's, 700R4, and 27" tires.

    If you want maximum economy, get 3.08 gears, a 700, and you'll see 20 + mpg, but not much power.

    Casey
     
  7. u2slow

    u2slow 1/2 ton status

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    TH400's just been rebuilt, and the rear end's days are numbered.

    3.21's are the plan - thanks guys! /forums/images/graemlins/burb.gif
     

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