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4.10's or 4.56's???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TB2Blazer, Apr 10, 2002.

  1. TB2Blazer

    TB2Blazer 1/2 ton status

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    4.10\'s or 4.56\'s???

    I have a 1985 K5 Blazer. It gets used %50 off-road and %50 on. I live in the north Georgia mountains. I am wondering what would be a better gear ratio for me the 4.10's or the 4.56's. I want it to have more torque. Will the 4.10's give it better gas mileage? Any help on the matter would be most appreciated. Thanks, TB2Blazer.
     
  2. fr8train

    fr8train 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    Fill out your profile. Auto or manual? Tires size?
     
  3. Blazinaire

    Blazinaire 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    I'm gonna have to say to go with the 4.10's. I have 35's w/aod tranny w/4.56's and it winds out fairly high on the highway. If you plan to go to 35''+ any time soon, go with the 4.56's.
     
  4. MudbogAD

    MudbogAD 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    I have 4.56's and 35's without an OD. My truck doesn't wind out that much on the highway. If you are on the trail 50% of the time go with 4.56's. Mine is a daily driver with 4.56's and I'm fine. I don't really see how 4.56's, 35's, and an OD could rev high at 65 MPH.
     
  5. fr8train

    fr8train 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    Whats your avg. speed? What is the rpm your at? I did some figuring on <a target="_blank" href=http://www.4lo.com>www.4lo.com</a> and with the od on a 700r4 your looking at +2300@75mph and 2009@65mph, thats with 34.7" tires ( not all tires actually the listed size, swampers are one of the exceptions)

    With 32.7" tires its +2100@65mph and +2400@75mph.
     
  6. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: 4.10\'s or 4.56\'s???

    I went with threw the same dilema awhile back. I know I am going to run 35's and probably 37's one day (a long time from now) so I decided to go with 4.56. I do alot of city and highway driving but I decided I might as well do it right the first time. So this summer my truck is getting the rear axle swapped to a 14bff (welded diff) with 4.56's and the front is getting regeared to the same. (locker or posi in front). I only have 32's right now, but overdrive will save me somewhat. Hope this helps a little.
     
  7. txbartman

    txbartman 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    It also depends on what gear size you are coming from. I originally had 3.73s in my rig. Going to 4.10s just wasn't going to be much of a difference. The 4.56s gave a noticeable difference. I had 3.73s with 32" ATs originally. I went to 4.56s with 35" MTs and the change in gear size just about countered the increased tire size. I have a 700 auto w/OD and am pleased with it. I do turn a little higher higway RPMs, but it actually helps as far as power goes when driving my 9'3" wall into the wind! Gas mileage impact was negligible compared to the wind resistance impact from the lights, rack, and spare tire on the roof.
     
  8. DesertDueler

    DesertDueler 1/2 ton status

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    Re: 4.10\'s or 4.56\'s???

    I would say 4.5s. My truck came stock with 3.73s and 31s. When I went to 4.56s and 35s, I got about the same MPG. My Jimmy gets 16 cruising downt the freeway at 80 mph.
     
  9. Blue85

    Blue85 Troll Premium Member

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    Re: 4.10\'s or 4.56\'s???

    I have 4.10 with a 700R-4 and 35" Pro Comps (about 34.2" actual). At 75mph, I am right at 2000rpm. This gearing overall is just slightly lower than my stock 3.08's with stock tires, so it is by no means super aggressive gearing. I had the 4.10's with 33's for a while (barely 32" actual) and it was actually really cool. With 35's I would be happy with 4.10 or 4.56 for street and trail. With any bigger tire, or mostly trail use, definately go 4.56.

    Low gears is maybe the best single mod I've ever done.
     
  10. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: 4.10\'s or 4.56\'s???

    I turn 2800 rpm at 80mph on 35's that are 35 inches tall.
    That's 4.10 gears no Overdrive and no lock up converter. With OD that your truck has you could go to 4.56's and take a little strain off the tranny. Probably be turning about 2400 or so at 80mph.
    Visit here www.gbr4wd.com
    Welcome to CK5
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: 4.10\'s or 4.56\'s???

    If you've got overdrive, 4.56s all the way.

    I have two trucks. One has 4.10s and 35s. It used to have a 700R4 and it wasn't enough gear. This summer, when I put it back together, it'll have a 4 speed, and the 4.10s will be ideal.

    My other truck has 265/75R16s. no overdrive, no lockup torque converter (TH 400) and 4.56s. It winds to the moon, but I don't care, it pulls my camper pretty good and it'll pull my new one too.
     

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