speedo gear

[moparker]

I need a little help. My 71 duster340 has 28" tall rear tires with a 3.91 gear.How many teeth or what color gear do I need. The car hasn't had a seedo cable since I've owned it. The gear I took out was a green 34 tooth. my year one catalog shows a chart and says the 34 is for 3.23. The chart also says I need a 40 tooth orange gear for 3.91. But it doesn't show all tire sizes(height). Any info on this will help. Thanks Mike

 

[1970duster440]

The calculator I use shows to use 36.62 teeth. I don't know if they make a 37 tooth but a 36 tooth will be close. I entered a 28"" tire diameter with 3.91 gears.

 

[dusterdon]

I have a 4.10 with 28" tires and my speedo is dead nuts with a 39 tooth gear.

 

['64 Cuda]

I have a 4.10 with 28" tires and my speedo is dead nuts with a 39 tooth gear.

Sorry to hear about your speedo's dead nuts. Hope they get better. :-D