View Single Post
Old 01-04-2023, 09:01 PM   #4
Accelo
Senior Member
 
Accelo's Avatar
 
Join Date: Mar 2015
Location: washington
Posts: 2,358
Re: 72 Saginaw 3 speed Speedo Drive gear?

With your current size tires;
If you go to the 21T gear your spedomete3r will be off by 2.3% fast.
If you go to the 22T gear your spedomete3r will be off by 2.32% slow

You should have the smaller of the two 8T gears. (The 1.76" OD gear).

I get a 7% difference, in speed, using 55/59mph and your existing tire size and the 8/21T gear? Almost three times the what the calculated speed difference should be. Go figure.
Accelo is offline   Reply With Quote