Speedometer gear

[Hank/Mi]

I have a 1931 coupe with 16 inch wheels, tire size 195 by 80 R16s, approximately 28 inches tall. Rear end ratio is 378. I have a 19 tooth gear which I think will be a little slow. Do you think 20 or 21 would be better ?

Thanks,
Hank

 

[Bill OH]

I would check your Model A speedometer on the highway with a portable GPS - you will find how much speedometer error you have. The 3.78 gears, 19 tooth turtle and 16 inch rims sound okay - not sure about the tires. I would check the speedometer at 30, 40, 50 & 60 and those speedometer readings, see what the GPS indicates.

Best wishes,

Bill

 

[Sparky]

If you increase the number of teeth it will be even slower. You need a gear with fewer teeth to speed it up.