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ORD doubler crawl ratio question

Discussion in 'The Garage' started by unick, Dec 19, 2003.

  1. unick

    unick 1/2 ton status

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    What would the crawl ratio be for a truck with an 87 700R4, ORD doubler, and 4.56 gears be?

    lmk
    Nick
     
  2. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    3.06 * 1.96 * 2 * 4.56= 54.698112 /forums/images/graemlins/thumb.gif
     
  3. mechted

    mechted 1 ton status Premium Member

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    3.06 x 3.96 x 4.56 = 55.25
     
  4. zakk

    zakk 1/2 ton status

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    add in the torque converter for 110:1

    I'm shooting for 153:1 /forums/images/graemlins/grin.gif
     
  5. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    Zakk, how does the torque converter work in to the formula? Are you just multiplying by two? Is it different for different torque convertors? Thanks.
     
  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    Zakk, how does the torque converter work in to the formula? Are you just multiplying by two? Is it different for different torque convertors? Thanks.

    [/ QUOTE ]


    The "stall" in the converter allows you to spin the engine without a direct 1:1 coupling to the tranny...the effect is estimated at about a 2:1 ratio (conservative) to maybe 3:1 (optimistic).....

    Once you hit the stall speed of the converter, the effect is gone. But for most of the slow speed stuff we do, this extra 2:1 reduction is REAL and welcomed! /forums/images/graemlins/thumb.gif
     
  7. sled_dog

    sled_dog 1 ton status

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    so in theory would puting a higher stall converter(not much say 1500) create a more optimal state? Cause you would still have the torque mutliplication?
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    so in theory would puting a higher stall converter(not much say 1500) create a more optimal state? Cause you would still have the torque mutliplication?

    [/ QUOTE ]


    From everything I've read, and seen on this site.....changing the stall speed is more likely to make things worse than better.

    Stall is a pretty tough thing to mess with from a "tuning" perspective. It's a PITA to get to the converter, and most of what I've heard indicates that you really need to understand what you're doing or you may just make your setup more unpleasant....

    I forget what factory "stall" is, but I thought it was up in the 2000+ RPM range anyway???? /forums/images/graemlins/thinking.gif
     
  9. cybrfire

    cybrfire 1 ton status Vendor GMOTM Winner

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    Thanks for the info. Makes sense I just never really thought about it that way.
     
  10. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    [ QUOTE ]
    3.06 x 3.96 x 4.56 = 55.25

    [/ QUOTE ]
    Close, but it's x2 not +2, big83 got it right. The farther away from 2:1 get the more wrong you will be. Klune-V "Goliath" & an NP241 (2.7:1 & 2.72:1) 102.48:1 vs 75.63:1 or Klune-V "David" & an Atlas (4:1 & 4.3:1) 240:1 vs 115.81:1.
     
  11. 88K5Jimmy

    88K5Jimmy 1/2 ton status

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    What do each of the number stand for in the formula? First gear ratio, low t-case ratio, a constant and gear ratio?

    Thanks
    Ross
     
  12. bigjbear

    bigjbear 1 ton status Staff Member Moderator

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    Trans 1st x range box x x-fer case low x R&P
    700R4 x NP203 range box x NP205 x his R&P ratio
    3.06:1 x 2:1 x 1.96:1 x 4.56

    In the example #s I used his 700R4 and R&P ratio to get the finial drive ratios listed.
     
  13. ntsqd

    ntsqd 1/2 ton status

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    [ QUOTE ]
    [ QUOTE ]
    Zakk, how does the torque converter work in to the formula? Are you just multiplying by two? Is it different for different torque convertors? Thanks.

    [/ QUOTE ]


    The "stall" in the converter allows you to spin the engine without a direct 1:1 coupling to the tranny...the effect is estimated at about a 2:1 ratio (conservative) to maybe 3:1 (optimistic).....

    Once you hit the stall speed of the converter, the effect is gone. But for most of the slow speed stuff we do, this extra 2:1 reduction is REAL and welcomed! /forums/images/graemlins/thumb.gif




    [/ QUOTE ]

    Somewhere in my Granddad's FSM or literature on his GMC motohome it states that the torque multiplication factor of the stock converter is 2.6:1 and cautions that only X p/n converter be used in the GMC coaches as the typical TH400 converter's factor is ~2.0-2.3:1 depending on application. Unfortunately he's already checked, that converter no longer exists in any inventory anywhere in the states.
     
  14. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

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    this is what i am shooting for:
    3.06 x 3:1 (wms) x 1.96 x 5.13 = 92.3 /forums/images/graemlins/eek.gif
     
  15. SF87K5

    SF87K5 1/2 ton status

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    I like this set up.
    3.06 x 2.72 x 5.13 x 2.7 =115.28 /forums/images/graemlins/thumb.gif
    Of course thats also with a $1700 Klune-V Goliath underdrive also. For those also woundering about the David's 4.1 underdrive. It is highky recommanded them not be used on full size trucks. Klune-V info page. /forums/images/graemlins/thumb.gif
     

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