Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: Gear ratio tag

  1. #1
    Join Date
    Apr 2009
    Location
    San Luis Obispo, California
    Posts
    283

    Default Gear ratio tag

    I just took the little gear ratio tag off my front differential of my 72 scout 2 and it has 2 numbers

    41 - 11

    and below that is etched

    3 73

    Which is my ratio.. im assuming its 3 73, and what does the first number mean..?

    Thanks guys
    -72 Scout2 - SBC350 with RV camshaft, 4 speed manual Trans, D20 xfer case with CV drive shafts.
    -Dana 44 Detroit locker rear.
    -Dana 44 (out of a 75) Rebuilt /w trutrac limited slip frnt



    ~Conquest is not in our principles. It is inconsistent with our government.

    ~T.J.

  2. #2
    Join Date
    Mar 2009
    Location
    California
    Posts
    110

    Default

    The first gives the number of teeth on the two gears; if you divide 41 by 11, you get 3.73 which is the ratio.

  3. #3
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    47=ring gear.
    11= pinion gear.

    They come as a matched set. You don't change one without the other. The backlash must be set so that the gears mesh, or else they wear out quickly.

    Other ratios used in scouts from the factory are 3.07, 3.31. 3.73, 4.09, but Dana made the gears also in 4.56, 2.73, etc.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  4. #4
    Join Date
    Apr 2009
    Location
    San Luis Obispo, California
    Posts
    283

    Default

    Sorry im kind of a noob at the gear ratio stuff and am trying to make more sense of this, if anyone has a good link to a explanation of it all that would be useful. And is 3.73 a good ratio for general offroading use?

    and what is the lowest ratio and what is the highest offered
    -72 Scout2 - SBC350 with RV camshaft, 4 speed manual Trans, D20 xfer case with CV drive shafts.
    -Dana 44 Detroit locker rear.
    -Dana 44 (out of a 75) Rebuilt /w trutrac limited slip frnt



    ~Conquest is not in our principles. It is inconsistent with our government.

    ~T.J.

  5. #5
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    Quote Originally Posted by WarlordX View Post
    Sorry im kind of a noob at the gear ratio stuff and am trying to make more sense of this, if anyone has a good link to a explanation of it all that would be useful. And is 3.73 a good ratio for general offroading use?

    and what is the lowest ratio and what is the highest offered
    if your wheels turn one time for every time the driveshaft turns, that's 1:1

    If your driveshaft has to turn 3.73 times to turn the wheels one full turn, that's a 3.73:1 gear ratio.

    The higher the number, the faster your engine has to go to run the wheels at a given speed.

    Therefore, the higher the gear ratio number, the slower you CAN go at a given rpm. This is very useful for crawling slowly over obstacles on a trail.

    The transmission has various gears. In first gear, you can go slower. It high gear, you must go faster or the engine will stall.

    The gear ratios in the transmission, transfer case, and axles are cumulative, and to get a final ratio, you multiply them. If you run 4:1 in first gear, 2:1 in low range, and have 4.09 gears in the axles, 4 times 2 times 4.09 (call it 4x2x4 to make it easy) is 32:1. Your engine runs 32 rpms for every turn of the tire. If you are running 1600 rpms, your tires turn 50 times a minute, or about 1.6 times per second.

    If your transmission has a "granny gear" you end up with 6.3:1 first gear, so 6.3 times 2 times 4.09= about 53. That means you can run slower.

    This is why many people buy aftermarket transfer cases with 4:1 gears or even higher (Stax has a 10:1 ratio available, if I recall correctly). It allows you to go really, really slow.

    Some people have found that the IH engine has a whole lot of torque at low rpm. This allows us to run 800 rpms where other people would have to run 1600 rpms, for example. Very useful sometimes.

    Adding these numbers (multiplying, actually) gives you what is often referred to as a "crawl ratio."

    The most common gearing in a scout is 3.73. I have seen stock gears of 4.88 in scout 80s, and 2.73 in Scout IIs. The range in pickup trucks is even wider, but 4.10 is the most common for IH.

    The front and back axles must be fairly close. 4.10 rear and 4.09 front is stock on IH pickups and travelalls. That's about a quarter of a percent difference, which is acceptable in dirt with no ill effects, but it can bind your drivelines on pavement if you are not careful.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  6. #6
    Join Date
    Apr 2009
    Location
    San Luis Obispo, California
    Posts
    283

    Default

    Wow thank you so much Allan, You have explained that incredibly well I feel much more learned in this field now he he :P And i actually understand it!

    That's interesting about the travelals having slightly different gears in front and rear, but i suppose they were assuming most people wouldn't ever really need to have 4wheel engaged on the pavement, which makes sense lol
    -72 Scout2 - SBC350 with RV camshaft, 4 speed manual Trans, D20 xfer case with CV drive shafts.
    -Dana 44 Detroit locker rear.
    -Dana 44 (out of a 75) Rebuilt /w trutrac limited slip frnt



    ~Conquest is not in our principles. It is inconsistent with our government.

    ~T.J.

  7. #7
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    Quote Originally Posted by WarlordX View Post
    Wow thank you so much Allan, You have explained that incredibly well I feel much more learned in this field now he he :P And i actually understand it!

    That's interesting about the travelals having slightly different gears in front and rear, but i suppose they were assuming most people wouldn't ever really need to have 4wheel engaged on the pavement, which makes sense lol
    The reason they are slightly different is that the 3/4 ton pickups and travelalls had different axles front and rear. Dana 60 comes in 4.10, and Dana 44 comes in 4.09. That's as close as they could get it. The half ton rigs have the same ratios.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  8. #8
    Join Date
    Apr 2009
    Location
    San Luis Obispo, California
    Posts
    283

    Default

    So got a front end from a 1976 scout 2 ( that i bought ha ha) with

    a 46-13
    3.54 gear ratio.


    Where would u suggest getting a D44 3.73 ring and pinion? and what would u suggest for front traction control.. I have the stock limited slip in the rear.

    What is best for rear? and what is best for front? For moderate to extreme offroading but not rock crawling.
    -72 Scout2 - SBC350 with RV camshaft, 4 speed manual Trans, D20 xfer case with CV drive shafts.
    -Dana 44 Detroit locker rear.
    -Dana 44 (out of a 75) Rebuilt /w trutrac limited slip frnt



    ~Conquest is not in our principles. It is inconsistent with our government.

    ~T.J.

  9. #9
    Join Date
    Feb 2009
    Location
    Aiken, SC
    Posts
    2,423

    Default

    I'd put the LS in the front and buy a locker for the rear for that purpose. You can swap front to back, back to front, and besides, it's likely time to rebuild the LS anyway. A stock rebuild kit should work just fine, especially if it's the ratio you want.

    Randy's Ring and Pinion? I think that's their name. Good reputation for gearsets, new and used.
    Allan E.
    Curmudgeon Extraordinaire
    Charter Member, Old Hippie IH Club
    Old fashioned binder freak

  10. #10
    Join Date
    Apr 2009
    Location
    San Luis Obispo, California
    Posts
    283

    Default

    Cool that was my thought as well I planned on rebuilding the rear one as well and eventually switch it to disc brakes but damn i have enough work on my hands he he :P and we all have our REAL jobs to worry about he he, The limited slip is the one that came stock in the 72 is that one garbage for 35 " tires?

    What brand of locker would you use if you were in my situation?
    -72 Scout2 - SBC350 with RV camshaft, 4 speed manual Trans, D20 xfer case with CV drive shafts.
    -Dana 44 Detroit locker rear.
    -Dana 44 (out of a 75) Rebuilt /w trutrac limited slip frnt



    ~Conquest is not in our principles. It is inconsistent with our government.

    ~T.J.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •