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Need help on gear ratio and selecting locker!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Takman, Mar 27, 2003.

  1. Takman

    Takman Registered Member

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    I have 90Blazer stock350/700 on 35in BFG, f&R GM Corp10 bolt(stock). I need to find out the best combo(gear ratio, posi or locker)package for my rear end upgrade and also front end. Could someone please help me on this project? I need to find out fllowing matter.
    1. Stock gear ratio on 90 K5 with 700trans
    2. Recommended gear ratio for all around vehicle (city, hiway, off-road)I am thinking 4.56 or 4.88?
    3. Recommended Locker Diff Assemblies for city, hi-way, off-road (mostly Pismo sand dune use) not much rock crawler.
    Can’t afford ARB.. may be Truetrac? Or stay with posi….?

    Thank you for looking
     
  2. k20

    k20 3/4 ton status

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    cant help ya with locker, but for gears id say 4.56 if you are planning on staying 35's for a while. But if they are getting low on tread and you might go to 37's or larger id say 4.88.
     
  3. 88sub4x4

    88sub4x4 1/2 ton status

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    Stock gear ratio's varied greatly. The only way to know for sure, is to look at the RPO codes in the glove box. Usually the ones starting with G are gear ratio related. You most likely have a 3.42 or 3.73 but that;s just a guess. An all around ratio for stock tires (31") would probably be about 4.10 any numerically higher would suck gas on the street. Plus you are only on sand dunes, not too much rock crawling, so you don't need extreme torque. I personally like the Eaton limited slip. It behaves well on road, and gives excellent, but not total, traction off road. The Auburn is a little cheaper, but is not rebuildable, but I was told that they will exchange the unit for 100 bucks if withinn 4 years from new. Do you plan on a lift or bigger tires? /forums/images/graemlins/burb.gif /forums/images/graemlins/k5.gif
     
  4. 88sub4x4

    88sub4x4 1/2 ton status

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    Ooops, sorry I missed the 35" tire thing. Id go with what K20 said though. /forums/images/graemlins/burb.gif /forums/images/graemlins/k5.gif
     
  5. DesertDueler

    DesertDueler 1/2 ton status

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    4.56s are good for all around, but suck for freeway driving. Even in OD, you still are cruising at high rpms. I ran 4.56s with 35s and with 38.5s. For city driving and offroading, the 35s were better, but for the freeway it was alot nicer cruising with 38.5s.

    Stock gears are probably 3.42, maybe 3.73s. For sand, a good posi would work just fine in the sand, and you wont feel a posi on the freeway.

    Dan
     
  6. bajaviking

    bajaviking 1/2 ton status

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    I think the gears start getting thin when you go higher than 4.56 so I would probably stick with that, it should be good for 35's and a OD tranny. If you really want traction go with a locker(I like my lock-right), if you don't wheel it a lot a good posi-unit might be more comfortable on the street. Just my $0.02.
     
  7. Takman

    Takman Registered Member

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    Thank you sooooo mcuh everybody!Each gave me info that I needed and Thank's for your well define comments.
    Happy wheeling!
     

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