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2:10 gear ratio?

Discussion in 'The Hokey Ass Message Board' started by noxided, Jul 17, 2011.

  1. noxided
    Joined: Aug 28, 2006
    Posts: 780

    noxided
    Member

    i checked the gear ratio on my 53 merc and i spun the shaft 2 turns to make the wheel spin one. so is that a 2:10 rear end? Ive never heard of that.

    So its time to change, i'd like to go over 45mph " not original trans"
     
  2. REM/Mo
    Joined: Feb 24, 2008
    Posts: 281

    REM/Mo
    Member
    from Missouri

    Probably 4:11.
    If you only let one wheel turn you have to let it go two revolutions as you count the driveshaft turns.
    A 2:10 ratio would be way fast. You would be idling at 60 mph.
     
  3. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,081

    Ned Ludd
    Member

    No, 2.000:1, provided it really was exactly two revolutions.

    Gear designers try to avoid simple round-number ratios, and often favour prime numbers of gear teeth or at least tooth counts that aren't common multiples, in order to avoid unwanted harmonics. So, if you've got 19/37 teeth, say, you'll have a 1.947:1. I'd be very surprised if you had 18/36!

    You'll certainly be able to go over 45mph. With, say, 26" tyres, a 5500rpm redline, and enough power to overcome aerodynamic drag at that speed you'd be able to go about 213mph. You'd need all week to get there, though.
     
  4. anteek
    Joined: Feb 27, 2009
    Posts: 394

    anteek
    Member

    The merc has a dana spicer 45 rear which should have a tag on one of the bolts of the rear cover. It will have the ratio. 4.11 was a common ratio with a 3 spd overdrive.
     

  5. noxided
    Joined: Aug 28, 2006
    Posts: 780

    noxided
    Member

    ok, thanks guys, i looked for a tag but its missing, so its all a guess till i get it apart.
     
  6. Ned Ludd
    Joined: May 15, 2009
    Posts: 4,081

    Ned Ludd
    Member

    9/37 gives 4.111:1

    REM/Mo makes a good point. If you only rotated one rear wheel, the other being prevented by being on the ground, say, you would have brought the differential into play, which would have caused the drive shaft to rotate half the number of revolutions it would have if both rear wheels rotated at the same speed. That would have given you a reading of 2.056:1 from a 4.111:1 rear.
     
  7. noxided
    Joined: Aug 28, 2006
    Posts: 780

    noxided
    Member

    Well, i had both rear wheels off the ground bt the passenger side did not rotate.

    Aslo here is the only id i could find on the axle after being fed grime from a wire wheel.
    1A4025
    [​IMG]
     
  8. burnin53
    Joined: Mar 22, 2009
    Posts: 596

    burnin53
    Member
    from cuba,n.y.

     
  9. Mart
    Joined: Mar 3, 2001
    Posts: 4,204

    Mart
    Member

    I put a video on youtube showing how to check an axle..
    The other wheel needs to be on the ground, and you need to rotate the raised wheel twice.

    Do not do this with a locker diff.

    Mart.

    http://www.youtube.com/watch?v=bkvp3Fq21ZM
     

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