WHAT SPEEDO/TRANS GEAR DO I NEED

[WAYNE0]

3:91 gears 27 1/2 inch tall tire do they go by the number of teeth or color of the gear or both

 

[Professor Fate]

What year trans- '65 and earlier or '66 and later? The style changed...
Speedometer Gear Ratios - Mopar A833 4-Speed Transmission & Component Specialists
Different tooth counts correspond to different colors, ie a '66 and later 37 tooth gear is white, a 36 tooth gear is red, etc.

 

[Dana67Dart]

Don't know if it's accurate but give it a try

Your FSM might have a list also. 67 does

 

[AJ/FormS]

If the car drives and has a working speedometer, you can calculate the change needed in percentage, from what the Speed-O says to What it Should say.
Then you just add or subtract that percentage to the current gear.
If the speed-O is slow, then it needs to spin faster, so you would subtract teeth, to speed it up.
This method is as accurate as you can maintain your speed to a known standard, and the faster the better.
Example
say you are traveling at a true groundspeed of 60 mph but your speed-o is saying 66mph, so is 10% fast, so you need to slow it down 10%, so you need MORE teeth.
If your gear has 34 teeth, then you need 1.1 x 34= 37.4 teeth, this rounds to 37, and the speed-O will read a hair fast.

 

[WAYNE0]

What year trans- '65 and earlier or '66 and later? The style changed...
Speedometer Gear Ratios - Mopar A833 4-Speed Transmission & Component Specialists
Different tooth counts correspond to different colors, ie a '66 and later 37 tooth gear is white, a 36 tooth gear is red, etc.

mm didnt know that its a 66 and later 833 4spd trans

 

[413]

You go by the number of teeth, the colors repeat.