Super T-10 speedometer calibration

Discussion in 'Camaro Questions' started by Jeep43, Jan 20, 2018.

  1. Jeep43

    Jeep43 Veteran Member

    Mar 30, 1999
    I am having an issue finding the right speedo gear setup for my car. The car has 3.73's and a super t-10. When I disassembled it it had the wrong driven gear but it was just the cable attached directly to the bullet.

    The speedo drive gear is 8 tooth and since its a large output St-10 I presume its a 1.84 OD gear. Online charts say I need a 23 tooth driven gear but they only make 23 tooth gears for 1.76 OD drive gears...... The closest I can get to is 22 tooth which is close but not accurate.

    Now looking at clill's pictures of the 900 mile 74Z, photos show a stewart warner speedo drive reducer. This would let me use a smaller gear in the range that works with the 1.84 OD drive gear. Is this the OE setup? My car is just missing the speedo reducer??
  2. NeoNeuro

    NeoNeuro Veteran Member

    Aug 4, 2014
    Panama City, FL
    I have the same setup. All original. There is no reducer. I have the tranny out. I'll try to remember to pull the speedo gear out and see what it is. FYI, the tires you get these days aren't quite the same circumference as the original tires from the 70s. Modern tires made my speedo run 2-3 mph slow at 35 mph. Got worse as I went faster. It would require a reducer to make it accurate again.

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