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37"-38" and 4:56?

Discussion in 'The Garage' started by stockk5, Sep 20, 2005.

  1. stockk5

    stockk5 1/2 ton status Premium Member

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    Hey. i tried to search and search for an answer on this but nothing ever comes up. I was wondering how would 37-38" tires and 4:56 gears feel and run on a k5. Would it be a good idea to go bigger gears? or would they feel alright. This is my DD and im into more trails w/ some rocks, not crazy rock crawling and mud.. I am running a 305, 700r, 208.. soon to be 350tbi
     
  2. 85HeartBurb

    85HeartBurb 1/2 ton status

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    I am running 39.5" with 4.56's 454/465/205 DD works for me!!! :D
     
  3. trailblazr81

    trailblazr81 1/2 ton status

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    I ran 4.56 gears with 35" tires in a 86 Blazer for a while. It was a 35/700R4/NP208 Dog. The 4.56's helped the thing outta the hole and was only a couple hundred RPM more than the stock 3.73's. I would think with the less torque of a 305 or mostly stock 350 go with 4.88's with a 38" tire. I just checked the tire hieght, gear ratio, speed calculator at Randy's Ring And Pinion websight and 4.56 gears with 38" tires put you a tad under stock 3.73's and 31" tires. Me... I would go 4.88, only about 100 RPM more than stock in OD.
     
  4. BurbLover

    BurbLover 1/2 ton status

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    I've got a TBI350/TH400/NP208 w/ 4.56s and 13/38/16 TSLs and it ran just fine in the trails and okay for the occasional road use.
     
  5. rdn2blazer

    rdn2blazer 1 ton status Premium Member

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    i have 4:88's and 38's going on my rig, 383, th400 trans. just will run up in the rpm's a bit on the freeway, no big deal, unless your worried with the fuel cost these days.
     
  6. Hossbaby50

    Hossbaby50 3/4 ton status

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    You need more gear. You need at least 4.88's but I would recommend 5.13's if you are planning using overdrive at any time. I run TPI 350, 700R4, 208, 4.56's, and 37" MTR's (really only 35") and I need more gear.

    I wanted more gear when I was running 35's and 4.56's. The only reason I haven't swapped in 5.13's is because I am swapping to a TH400 tranny next and I won't have OD.

    Harley
     
  7. Leper

    Leper 1/2 ton status

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    The 700 has overdrive so go at least 4.88. I am changing mine to 4.56 with 35"
     
  8. 6.2Blazer

    6.2Blazer 1/2 ton status

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    4.56's would be liveable but you won't be using OD very much. With that said if your axles already have 4.56's installed I would try them first and see what you think. If you are actually swapping in new 4.56 gears than I would say don't waste your money and go straight to 5.13's.
     
  9. paulmoon

    paulmoon 1/2 ton status

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    I'm running TPI350/Th350/NP205/4:88's with MTR 37's on my DD. Not a lot of freeway driving but it's OK wheb I do. RPM's aren't too bad even without OD. With 38's I'd go a least 4:88 if not 5:13's...IMHO
     
  10. 85mudblazin

    85mudblazin 1/2 ton status

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    Im running 5.13's with my 35's. At about 65mph I am turning around 2600RPM which isnt bad for my motors range.
    I went from 4.88's to the 5.13's and I cant really tell much of a difference on the highway other then the 200RPM bump at high way speeds. But when in low crawling I can tell a BIG difference.
     
  11. BigCountryx

    BigCountryx 1/2 ton status

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    I know deeper is better, but 4.56's and 37's-38's would not be terrible. I mean it would be ton's better than running the stock 3.08's that I have now with 31's. For the love of God, this ratio is horrible, it's not even on the Chart and It is still bearable. I'm gonna be running 4.56's with 40's for a while 'till I can regear, and don't expect it to be that bad based off of my present setup. I'll just not use OD if it comes to that.
     
  12. sledheadak

    sledheadak 1/2 ton status GMOTM Winner

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    try 2.73s and 36s. :eek1: :eek1: really sucks but i get 15 mpg or on the trail lol
     
  13. BigCountryx

    BigCountryx 1/2 ton status

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    What tranny do you have? Sounds like a bomb in the making!
     
  14. zero cool

    zero cool 1/2 ton status

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    I wrote a little Java craplet to do side-by-side comparisons of gear ratio changes...

    http://www.dfw-tx4wd.org/gears.html

    Oh, and it doesn't have the NP241 in it. Just use the NP242, it has the same low range. That's on my (rather long) list of things to add.
     
  15. muddybuddy

    muddybuddy 3/4 ton status

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    it depends on which tranny you got. 700, go with 5.13s. for 350/400 go with 4.56
     
  16. sledheadak

    sledheadak 1/2 ton status GMOTM Winner

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    i have a th350 in it now.i am replacing the axles with d60/14b with 4.1-s for now it will go to 5.13s next year.
     
  17. Leper

    Leper 1/2 ton status

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    That is in the favorites list now
     
  18. JEBSR

    JEBSR 1/2 ton status

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    I am running 38.5's with 456's and I do good all around, But I have a 465 trans in mine so I have the granny low for off road. I would have to agree with most of the other post. If you are buying gears regaurdless get at least 488 and 513's would be perfect. Otherwise you will suffer off road at times and will loose a lot of power in OD.
     
  19. SUBFAN

    SUBFAN 1/2 ton status

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    Go as deep as you can go with the 700R4.

    I chose 4.56 for my OD trans, but I plan to swap to a T400 in the future. I will probably want more gear in the future too....
     

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