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spining 37s like 27s

Discussion in '40- & 55-Series Tech' started by lowtideride, Nov 5, 2003.

  1. lowtideride

    lowtideride

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    what kind of gears will spin 37s like 27s (4.88)??? thanks al
     
  2. geocrasher

    geocrasher

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    Just check out 4lo.com's gear calc, click on change tire size. It says 5.63's, but of course there is no such animal. 5.29 is the lowest you could go.
     
  3. CruisinGA

    CruisinGA

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    I prefer to compensate for larger tires by adding a transmission with a lower first gear, thus improving highway and byway(offroad) performance. 7:1 first on a SM420 would spin 37's with 4.11's like villains. I missed my calling as a rapper. Even the 4.9 of the H41 non-usa tranny would do the trick. Total cost of my Sm420 convo will be less than the cost to regear.
     
  4. woody

    woody unhelpful spotter Staff Member Admin

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    sm420 addresses offroad, but doesn't address on road.

    5.29's require some nasty ring gear grinding to slip in the cross pin on c-clip stock rear axles, 4.88's only require a little bit.

    I6 or SBC?? I have no highway issues with 4.11 stockers and 38.5 tires with my 350 TBI. I do NOT like the SM465 in town tho, a true 4-speed is nicer for that (SM420 would have the same problem)
     
  5. Medusa

    Medusa

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    How does a lower first gear improve highway performance ??? The question that I believe was being asked relates to compensating for the larger tires on the highway in high gear. As Ryan noted you are limited to 4.88 or 5.29 and there are problems with the 5.29 gear sets.
     
  6. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    Hijack!

    [quote author=Medusa As Ryan noted you are limited to 4.88 or 5.29 and there are problems with the 5.29 gear sets.
    Medusa: Please explaine these *problems* with the Land Cruiser 5:29 gear sets. I have installed a set with ARB's in a 69-40 two years ago, and they seem to be working very well for him. We had installed a Warn full float kit in the rear earlier, negating the cross-pin remove/install issue with this and the 4:88 gear sets.
     
  7. wngrog

    wngrog SILVER Star

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    David Reljac in my club has 5.29's, a stock H42 4 speed and 37" MTR's and his speedometer is DEAD ON!

    It really is cool wheeling this rig with 37's off road like you are running stock tires.

    It is a nice setup.

    He had to grind the ring gear so the center pin would fit in the rear, but it is not too bad.

    Done properly they should last under severe abuse.

    Gunracer1 (Mike Shannon) used to have a set in his FJ-62 and he abused the hell out of them with no breakage.

    I think it is a super option if you plan on building a rig around Cruiser axles and 37's.

    Add an Orion when they come out and BINGO!
     
  8. lowtideride

    lowtideride

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    im digging the idea of having the first gear lower than normal and keeping the stock gearing... how much green do you think the will run me..but then agian i dont want it to be a dog up any hills and beening an fj60 it already is a dog up big hills, im talkin 3rd gear doing 30ish while just spinning 31s..anyway i spend my winters in florida and my summers in PA and there is some long /steep hills there and thats where it was a dog..so what do you think my best would be? thanks-al
     
  9. CruisinGA

    CruisinGA

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    [quote author=Medusa link=board=1;threadid=7168;start=msg59450#msg59450 date=1068078684]
    How does a lower first gear improve highway performance ??? [/quote]
    If you have a lower first gear, you reduce the need for regearing the diff. By running large tires, with a lower first gear to compensate for starts etc, and stock diff gears, you have created a poor mans overdrive.
    Edit: I didn't realize it, but are we talking the other side of the spectrum? Too low rpm's on the highway? My problem is that mine are too high, so I automatically assumed that is what was needing to be fixed.
     
  10. lowtideride

    lowtideride

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    my rpms are high too but i know if i slap 37s on it will have no power,ill have to get out and push it up the hill or put in 4 wheel low
     
  11. lowtideride

    lowtideride

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    someone respond to what i wrote above crusinga , i know its only been a few mins..im so bored i could cry...
     
  12. Poser

    Poser Oh...Durka Durka Durka. s-Moderator Supporting Vendor

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    [quote author=lowtideride link=board=1;threadid=7168;start=msg59544#msg59544 date=1068090531]
    someone respond to what i wrote above crusinga , i know its only been a few mins..im so bored i could cry...

    [/quote]


    Get off the computer, and get back in the shop, working on your truck!! :p

    Where are your priorities!?!?!?!
     
  13. kling-on

    kling-on Kool Arrow

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    [quote author=lowtideride link=board=1;threadid=7168;start=msg59544#msg59544 date=1068090531]
    someone respond to what i wrote above crusinga , i know its only been a few mins..im so bored i could cry...

    [/quote]

    stock tire 29
    new tire 37
    old diff 3.90
    37 div 29= 1.27
    1.27 x 3.90 = 4.95 so 488 will be just under stock and 5.29 will be just over

    i do 5.29 for the grunt on the hills add h55f later if yoyu want more top end :D
     
  14. CruisinGA

    CruisinGA

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    Well with 37's and 62 or 40 series gears (4.10) that you could get pretty easily, and 37's, you will be doing 2612 RPM's at 70 MPH. Now with the lower first gear of H41 you should be fine on power for starts and around town, without the massive first to second gap of the GM granny trannies.
    The other route would be to regear to 5.29 and then throw in a H55, putting you with a good first gear, decent crawl ratio, and then you'd be doing 2300 rpm at 70 mph with that O/D.
     
  15. hendo

    hendo

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    thats the best reply i,m all for that idea .low rpms on freeway low crawl ratio on the trail