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Rear Axle Ratio on a 41' Plymouth coupe ?

Discussion in 'The Hokey Ass Message Board' started by Cadillac Jason, Oct 19, 2010.

  1. Need help with the ratio on this rear end ?...


    Jason Lee-
  2. I am not sure this works, but make a chalk line on the driveshaft. Jack one wheel in the air and spin it 360 degrees while counting how many times the driveshaft spins a full turn before the wheel makes it all the way around.

    If you have a little more then 4 turns ...its a 4:10
    If you have a little more then 3.5 turns ...its a 3:73
  3. 31Hudson
    Joined: Sep 6, 2010
    Posts: 25


    Ring gear grooves divided by pinion grooves equals ratio..
  4. The axle is in the car with no drive shaft

  5. F&J
    Joined: Apr 5, 2007
    Posts: 13,223


    You need to go two turns of the wheel exactly, to count the driveshaft yoke turns. The other wheel needs to be on the ground or not moving at all.
  6. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,248


    The reason you do two full turns is to compensate for the reduction thru the differential. If the rearend were a Posi, you would need to jack both wheels off the ground and just rotate the wheels once (together) as the Posi has clutches to keep the diff from working under light loads.

    No shaft...mark the yoke that the shaft attaches to.

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