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what gears for my combo

Discussion in 'The Garage' started by GMC500, Jan 23, 2006.

  1. GMC500

    GMC500 1/2 ton status

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    hello all

    I tried to do a search with 3.73, 4.10 or 3.42 but with no success

    Sorry - no matches. Please try some different terms.

    anyway

    my combo
    1986 GMC k1500 shortbed pick-up
    stock height - no lift YET :rolleyes:

    350 sbc
    L98 aluminum heads
    comp Xtreme 4x4 12-239-3 cam
    CR 9.0 - 9.5:1
    edelbrock performer intake manifold
    stock Q-jet :confused: ( will be replaced with ....... ? )
    stock exhaust manifolds ( I'll buy long tubes ASAP )
    dual 2.5" exhaust + glasspacks
    stock HEI dizzy + MSD in-cap coil and module ( OK it was stock :D )

    SM465 + np205 + stock 10-bolts
    I've opened the rear-end and it is a limited slip unit with 40:13 stamped on the ring = 3.07 :doah:

    33" tires ( actual size is about 32.7" )

    I'll use it in sand dunes no rocks, no mud

    what gears should I use ?

    thanks
     
  2. Leper

    Leper 1/2 ton status

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    You said "no lift...yet". So I think you should do your lift and then decide what size tires you will end up with. Do you do any street driving with it?
    Then decide what gear you need.
     
  3. sandawgk5

    sandawgk5 3/4 ton status

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    As far as the search it will not look for anything less than 4 characters which I dont believe a period counts. Try a wildcard by placing an * in front like *3.73, *4.10.

    As for gear choice it is a 10 bolt I would not waste the money but if you must I vote for 5.13s:D .

    Also are you sure it is a limited slip and not a gov-bomb? Does it have springs between the spider gears in a normal looking carrier or does it have some machined blocks with a carrier that looks like 1 side has been cutout.

    Ira
     
  4. GMC500

    GMC500 1/2 ton status

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    I don't have plans to use bigger tires
    but I'll do maybe a 4" lift in the future

    and yes I do drive it on the streets but it is not my daily driver



    sorry I thought they were the same :D
    it has a big S shaped spring in the middle and some clutch plates in the right
    what do you call it ? :confused:
     
  5. sandawgk5

    sandawgk5 3/4 ton status

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    Ya the s shaped clip is what provides the preload to the clutches in I think an auburn limited slip. A gov-bomb is obvious it has all kinds of pawls and a huge H shaped block a little governor thing and some clutches on one side. I was not doubting you just trying to make sure of what you had.

    Ira
     
  6. Leper

    Leper 1/2 ton status

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    With 33"s and assuming a no-overdrive tranny I would say no numerically larger than 4.10. So 3.73 or 4.10. If you do much highway driving, no bigger than 3.73.
     
  7. GMC500

    GMC500 1/2 ton status

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    thanks a lot
     
  8. zeroz400

    zeroz400 1/2 ton status

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    If it has 3.08s like mine, then it prolly has a gov-bomb. I doubt someone would drop the money for a limited slip and stay with those gears. I got 2 12bolts-308s and gov-bombs. Might wanna look at getting a locker for it.
     
  9. hack500

    hack500 1/2 ton status

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    if it's just sand I'd say keep the 3.08's and get some bigger/wider tires when do the lift.
     
  10. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Well if you want to keep a top speed of more than 55 I say go with a 3.73. A 4.10 might be too much without overdrive. I have a symilar combo, with the SM465, 3.08 10bolts, and 35s. I have already done a gear swap to a 4.10 and at about 65 I'm churning at 2800rpm. So if you had 4.10s you'd be over 3000rpm screaming dowm the highway.
     
  11. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    If you have no intention of going bigger , and no intention of running rocks , and since you have a sm465 and a nice 350 .

    Get experience first and decide what you want to do .

    I had 3.08's with 33's before , and it was slow off the line , but was liveable for awhile until I scored lower axles cheap .
     
  12. GMC500

    GMC500 1/2 ton status

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    pauly383k10

    yes I have to test it first
    but unfortunately I don't have time now due to final exams :doah:
    maybe after 2 weeks :D

    thanks
     
  13. gm500hprat

    gm500hprat 1/2 ton status

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    My buddy had a 73 longbed with 33's and 4.11's in the sand its an awesome combo.get some serious performance.He was by far the fastest street truck up the hill at the sand dunes...But I guess the 350 hp 400 sb probably helped some too..;) ....It was doable on the highway if you werent going beyond 60-65 range...
     

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