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Ring And Pinion With Mismatched Numbers

Discussion in 'Early CJ5 and CJ6 Tech' started by johnsotd, Apr 23, 2017.

  1. Apr 23, 2017
    johnsotd

    johnsotd Member

    Senatobia, MS
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    what will happen if I run a front axle with mismatched ring and pinion numbers?
     
  2. Apr 23, 2017
    oldtime

    oldtime oldtime

    St. Charles,...
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    Really not much telling.
    They may possibly match up near perfect.
    But you should also accept that the service life may be severely compromised.
     
    Posimoto likes this.
  3. Apr 23, 2017
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

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    for example are you referring to gear ratio
    4:88 front & 5:88 rear
    it will run in 2WD only
    1"st time in 4WD something is going to explode
     
  4. Apr 23, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

    Apopka, Fl
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    I was wondering if he meant that or a r & p that isn't a matched set.
     
  5. Apr 23, 2017
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    This is what I understood from the question... but he could mean mismatched axles ...
     
  6. Apr 23, 2017
    wheelie

    wheelie beeg dummy Sponsor 2019 Sponsor

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    I was thinking he meant say....a 4.88 ring gear and a maybe a 4.27 pinion gear. Not really sure. I would think that even a used pinion from the same gear ratio that is not the one that ran with the original ring gear (4.27 pinion gear from one axle and 4.27 ring gear from another) may eventually have some wear issues. Might get them set up and looking okay but, since they aren't a matched set, they may wear prematurely......if you can get them to pattern well in the first place.

    This is pure speculation on my part. I am not gear head and I did not sleep at a Holiday Inn Express last night.
     
  7. Apr 23, 2017
    johnsotd

    johnsotd Member

    Senatobia, MS
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    Both gear ratio's are 5.88. The R&P are not a matched set. When I opened the differential
    the wear pattern actually looked good. I will try to post a photo.
     
  8. Apr 23, 2017
    Rich M.

    Rich M. Shoe pusher

    Maryland
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    Front axle , run it dont worry.
     
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  9. Apr 23, 2017
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    This would be my thinking too. Duty cycle is so low on the front axle, you'll get away with it.
     
  10. Apr 23, 2017
    Glenn

    Glenn Kinda grumpy old man Staff Member Sponsor

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    Don't feel bad, it never helped me either. :D
     
  11. Apr 23, 2017
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    5.88? or 5.38?
     
  12. Apr 23, 2017
    johnsotd

    johnsotd Member

    Senatobia, MS
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    Sorry, 5.38
     
  13. Apr 24, 2017
    oldtime

    oldtime oldtime

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    Yeah that's what I think.
    Run it as is.
    So long as the ratios are identical its mostly O.K.
    Mismatched R+P may not be ideal but it really depends on how well the gear tooth face angles mesh up.
    Prussian blue will reveal the true fit.
    Heck I've seen supposedly matched R+P that did not match very well according to the prussian blue.
    It will get noisy if its not happy.
     
  14. Apr 24, 2017
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    Just don't run it on dry asphalt.
     
  15. Apr 24, 2017
    johnsotd

    johnsotd Member

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    I will install and check contact pattern.
     
  16. Apr 24, 2017
    nickmil

    nickmil In mothballs. Sponsor

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    If they are already installed and no issues I would probably continue to run them. I would never intentionally install mismatched ring and pinion gears as it is a lot of work and too much to go wrong by rolling the dice on it.
     
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  17. Apr 24, 2017
    johnsotd

    johnsotd Member

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    The gears were used in a complete axle that I bought. I don't know the history but the teeth on both R&P looked good but there was some slack somewhere (maybe in the spider gears) but the backlash on the ring gear felt like it was in spec. I did not find out about the mismatched R&P until I tore it down to clean it up and check the bearings. I just set the pinion bearing preload and will try to check the gear mesh pattern tomorrow.
     
  18. Apr 25, 2017
    Mcruff

    Mcruff Earlycj5 Machinist Sponsor

    Albertville, AL
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    Just as a bit of information. Ring and Pinions are not made as a set. They are made to a tolerance in large batches. They are matched so to speak by checking to a known standard and then marked and matched together buy the fit based on the tolerances. Any 2 gears could in theory be used so long as the wear is not excessive, front axles don't get used much so there easier than a set for the rear drive gears.
     
  19. Apr 26, 2017
    johnsotd

    johnsotd Member

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    upload_2017-4-25_23-12-26.jpeg


    upload_2017-4-25_23-13-39.jpeg

    Here are photos of the contact pattern. The ring gear backlash is .003.
    What do you think?
    Thanks
     
  20. Apr 26, 2017
    nickmil

    nickmil In mothballs. Sponsor

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    True, they are not manufactured as a set, but they are lapped together on machinery. that's why it's important to make sure the numbers match and why they number match them to begin with.
     

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