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Need some big gear opinions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by CaptCrunch, Dec 11, 2001.

  1. CaptCrunch

    CaptCrunch 1/2 ton status

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    I'm just kinda wondering if anyone out there has some numbers for me with a OD tranny, 4.56 or 4.88 gears, and anywhere from 35" MT's up to 38" Swampers. Opinions and any fuel economy numbers on the freeway would be great.

    Basically for those who don't know I have an 87 w/ 700R4 and 208 Tcase, 6" BDS lift and some kinda short (measure about 33-33 1/4" tall on truck) Pro Comp MT's. Plans this spring will bring a new modified 350 with FI of some variety. Basically after this summer I'm quiting the auto technican field down the toliet and will be going to school about an hour and a half south of here. The truck will be a daily driver and will make the trek back and forth quite a few times. Obviously this thing ain't gonna be a a great milage beast but I don't want to have to take a loan out to come to the cities to see family and friends. Here are the OD numbers I'm looking at w/ a real world 35" tall tire. Also is it worth the expense to go more gear or would finding a already equipped 4.10 be about the same?

    4.56's @ 65 mph= 2000 rpm minus TC lockup (add approx 200 rpm)
    4.88's =2150 rpm " " "

    I may jump up to 37's or 38's this spring, but I would still most likely driving a 35" MT or AT during the winter months (or dang near 8 months of the year here) BTW... tire clearance will come from maybe and 1" more lift and cutt'n fenders.

    Ok boys and girls with big gears(4.10's+)... what's your thoughts? Thanks in advance.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  2. ftn96

    ftn96 1/2 ton status

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    Well, Mike... I have a 700 as you know and Im running the 4.56 gears with a true 36" tire. And this setup seems to be working real well. I have plenty of power for the stop and go, and a good solid 70-75mph crusing range with the OD on the interstate. Its a little wound up but its great with the OD cause it keeps the tranny from un-locking and trying to down shift all the time.
    If I were you I would go 4.56 and stay there. Hell White Knight is running 44's with 4.10's[​IMG]
    Plus, since your into drag racing Im sure you rather have something with a little more get up and go. So the un-true 35's will set you a little higher up the RPM range but that will be temp till you get the bigger tires.

    Still hoping the GOV'T will ban the use of loud stereos with RAP music. [​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     
  3. txbartman

    txbartman 1/2 ton status

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    Well, I'm running 700R4/208 with BFG MT 35x12.50s. I swapped in 4.56s to replace my 3.73s. I have been very pleased. I still run 10-bolt axles, so I didn't want to go any taller. I heard that the pinion on a 4.88 10-bolt gear is really getting small and vulnerable.

    I run a weak 305, but have been pleased with the performance of the 4.56s. When I swap in my new 350, I will really be able to hang! I plan to go with 38s on my trail rig and will probably go with the same 4.56 gears.

    Hope this helps.

    Brian
    Check out <a target="_blank" href=http://tx85gmcguy.alloffroad.com>My Jimmy</a> with all her projects!
     
  4. CaptCrunch

    CaptCrunch 1/2 ton status

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    ttt

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     

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