Saginaw 4-speed gear ratios

Discussion in 'VIN, Trim Tag & Drivetrain Decoding' started by Jimmer, Mar 12, 2011.

  1. Jimmer

    Jimmer Veteran Member

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    Here is a tough question, how can you tell the gear ratios of an installed saginaw 4 speed tranny? The only means I have found is to count the rings on the input shaft which obviously can not be seen installed in car. Is there any experts that can help? Thank you very much for your help !
     
  2. LT1M22

    LT1M22 Veteran Member

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    Jack up the rear wheels, put the trans in first gear, make a mark on the driveshaft and the engine balancer at 12:00. Turn engine over by hand and have a friend look at the driveshaft mark and tell you when it makes 1 revolution. The number of times the engine turns past 12:00 to make one revolution of the drive shaft equals your 1 gear ratio.

    EX. 3 and a half turn equals a 3.5 ratio for first gear

    Saginaw 4 speed
    1st 2nd 3rd 4th
    3.50-2.48-1.65-1.00
    3.11-2.20-1.47-1.00
    2.85-2.01-1.47-1.00
    2.54-1.80-1.44-1.00


    Hope that helps
     
  3. Jimmer

    Jimmer Veteran Member

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    Very clever, thanks for your help, turn clockwise the motor, right?
     
  4. Rene Melten

    Rene Melten Veteran Member Lifetime Gold Member

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  5. 1980RS

    1980RS Veteran Member

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    No ring on the input is a 2.54 1 ring is a 2.85 and that is the best one. The other 2 are just waiting to explode, Both are weak, Not as weal as a T-5 but weak.
     
  6. Jimmer

    Jimmer Veteran Member

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    I will find out my ratio, but it must be the good one because I have hammered on the saginaw and it has never failed me yet!
     
  7. Jimmer

    Jimmer Veteran Member

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    When I marked dead center on motor and turned the driveshaft didnt start turning until the motors had been spun a little over a quarter turn. Do I need to start revolution counting at that point or whwn I did LT1M22 ? Thanks.
     
  8. yankee phil

    yankee phil New Member

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    You got it backwards,no ring is 2.85 and one ring is 2.54 for first gear. The 2.54 trans is saginaw's close ratio offering, probably why its the strongest of the brand.
     

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