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FOUND NP205 Max Torque rating!

Discussion in 'The Garage' started by nvrenuf, Jul 3, 2003.

  1. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Here is an excerpt from a post on Pirate concerning the elusive search for NP205 max torque ratings;

    <font color="blue">From Kenneth Koliba @ NVG :

    "The 205 was originally rated at 1100 ftlb input torque for Dodge, GM, Export and Military. The low ratio is 1.96 to 1, The high ratio is 1 to 1. Approximate weight is 156 lb. It was later rated 1500 ftlb in 1989."
    </font>

    This answer is the response from NVG to a Pirate user email inquiry, I thought that was pretty cool! /forums/images/graemlins/thinking.gif
     
  2. Paxx

    Paxx 1/2 ton status

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    /forums/images/graemlins/thumb.gif
     
  3. Toledo

    Toledo 1/2 ton status

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    sweet... so did they change parts in 89 or jus the rating? How can you tell when one was made if at all.
     
  4. chebywanna

    chebywanna 1/2 ton status

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    soooo..... 1500 ft/lb - 350 ft/lb = 1150 ft/lb remaining..... lots of work remaining /forums/images/graemlins/1zhelp.gif
     
  5. Silver84k5

    Silver84k5 1/2 ton status

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    [ QUOTE ]
    Approximate weight is 156 lb

    [/ QUOTE ]

    godamn it feels a lot heavier then that when your trying to put it under your rig.
     
  6. u2slow

    u2slow 1/2 ton status

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    AFAIK, the internals did not change. The 29 (Dodge), 31 (Ford) and 32 (GM) spline versions will no doubt be stronger than the smaller 23 (Dodge), 27 (GM), and 10 (GM) spline versions.

    My guess is the old rating wasn't revised until Dodge put out the Cummins trucks in '89. I wonder how much destructive testing was done /forums/images/graemlins/thinking.gif
     
  7. Highjaxx

    Highjaxx 1/2 ton status

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    Wouldn't your torque be multiplied by your tranny? And 203 in a doubler?

    I've been curious about this.

    IF my calculations are right!?!?

    I will put out 400ft/lbs(engine)x3.06(trans)x3.96(doubler)x5.13(gears)=24865.3ft/lbs???

    x2 for torque converter=49730.6ft/lbs!!!!! /forums/images/graemlins/shocked.gif

    At the tires/4 = 12432.7 per tire /forums/images/graemlins/burb.gif

    Is this even close? I have to be doing something wrong.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Are the results found in this chart http://www.newventuregear.com/tcases.html

    figured different than what was quoted as being the max input on the 205? If it isn't, I find it hard to believe that the "small" chain drive cases are stronger than the 205. /forums/images/graemlins/confused.gif
     
  9. HarryH3

    HarryH3 1 ton status Author

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    You can drop the 5.13 for the axle gears. They're after the 205, so it doesn't see that torque. /forums/images/graemlins/cool.gif You can also drop half of the doubler calculation, since you included the extra torque produced by splitting the gears once more in the 205 itself.

    But you're still looking at 2448 ft/lbs at the input side of the 205 with that 203 case in front, plus anything extra that the torque converter can provide. /forums/images/graemlins/eek.gif
     
  10. u2slow

    u2slow 1/2 ton status

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    [ QUOTE ]
    But you're still looking at 2448 ft/lbs at the input side of the 205 with that 203 case in front, plus anything extra that the torque converter can provide.

    [/ QUOTE ]

    Providing you don't snap an axle or u-joint first /forums/images/graemlins/wink.gif
     
  11. doctor4x4

    doctor4x4 1/2 ton status

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    cool link thanks man
     
  12. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    [ QUOTE ]
    sweet... so did they change parts in 89 or jus the rating? How can you tell when one was made if at all.

    [/ QUOTE ]
    I wonder if it was two different versions of input shaft. The Corse 10 spline may have been the 1100 that was behind the older 465 trucks. Maybe the 1500 rating is for the 32 spline input. Whats still strange is the 89 would have been a slip yoke most likely.
     
  13. tarussell

    tarussell 1/2 ton status

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    EXCELLANT info !!! John , you should actually do something other than search the web while you are at work ......Ha,ha

    A few thoughts to consider while discussing input torgue of gear boxes :
    the difference between applied torque and max torque
    the continous torque rating and intermittent(sp)ratings
    the "service factor" that the rating was measured at

    I would think that most of us are not using ALL of our engines torque at crawl speed while we are in the lowest gear possible. Even if a full throttle attempt is made it might only be for a brief moment and hopefully with minimum shock load .
    I believe that the ratings that are given are at full load ( meaning at max GCVWR ) and maximum traction conditions.
    We also need to look at longevity of the design . The 205 was , no doubt , built to last with some versions coming with maximum capacity radial bearings when needed and the use of oposing(sp) tapperd roller bearings for the idler shaft support .Fairly thick helical cut gears with descent size contact patterns all help to let this design put up with some serious abuse .
    The only common failure that I continously hear about is rear output shaft breakage on extreme traction applications ( sled pullers with HUGE motors ). Maybe N.P. would have upgraded the rear shaft diameter if there was a need while the case was in production but most of the motors ( Cummins excluded ) did not put out that much power to make an increase in strength needed .
    My whole point for jumping in on this is - don't worry about the fairly low rating number there are a lot more factors involved and not all are measured equally .
    HTH , Tom
     
  14. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    Whats still strange is the 89 would have been a slip yoke most likely.

    [/ QUOTE ]
    But the slip yoke isn't an inherently weak design. In stock applications the rear driveshaft is on a very shallow angle, so the slip yoke can slip pretty easliy. It's only when you start sideloading the slip yoke due to the increased angle induced by a lift kit that they start breaking. /forums/images/graemlins/frown.gif

    The big truck manufacturers don't care if you break it by modifying your truck. They only have to warranty it to work within their stock design specs. /forums/images/graemlins/shocked.gif
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    350 lbs of torque x 6.55:1 first gear = double the rated max input. Max potential torque at the axles is 20,500 lbs /forums/images/graemlins/eek.gif

    Rene
     
  16. m j

    m j 1/2 ton status

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    makes sense.
    same logic as running from an angry bear.
    I dont have to be faster then the bear, just faster then you.

    the torque rating of the 205 is irrelevant if it exceeds the driveshaft torque rating
     
  17. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    350 lbs of torque x 6.55:1 first gear = double the rated max input. Max potential torque at the axles is 20,500 lbs /forums/images/graemlins/eek.gif
    Rene

    [/ QUOTE ]

    Those were my thoughts exactly. That has to be wrong. Even a 305 puts it over that rating, and the 465/205 combo was offered in big blocks and diesels.

    I cry BULLSHIT!!!!
     
  18. tarussell

    tarussell 1/2 ton status

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    I would think that most applications would not use ALL of the engines torque while in such a low gear . If there were a graph that could show applied torque at every RPM throughout the gear changes it would more than likely be well with in limits .
    I am not trying to make an argument or anything , just point out that most engines never get a chance ( or get loaded enough ) to make any where near full torque while in a granny gear .
    I believe that the ratings are calculated with a bunch of factors - not just input torque numbers. JMHO , Tom
     
  19. Twiz

    Twiz 1/2 ton status

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    [ QUOTE ]
    I dont have to be faster then the bear, just faster then you.

    [/ QUOTE ]


    I'm soooooo, gonna swipe that! Nice one. /forums/images/graemlins/grin.gif
     
  20. Twiz

    Twiz 1/2 ton status

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    [ QUOTE ]
    most applications would not use ALL of the engines torque while in such a low gear .

    [/ QUOTE ]

    Agreed, I also doubt a engine can hit it's torque peek while in double low. It doesn't have enough time to take in a full breath of air, revs too quick.
    Peek torque occurs when a engine reaches it's highest Volume Metric Efficiency. Meaning.. 350 cubic inches of air (or more) is brought in during the intake stroke, that takes time.
     

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