More or Less?

[GPoppyof2]

I know there are formulas that tell you which speedometer drive and driven gear you need depending on differential ratios, tire size, etc. Regardless of these facts, which direction should one take to increase the speedo cable speed? For example, if my speedo reads 40 MPH and I am actually going 50 MPH, do I need to increase the number of teeth on the driven gear or reduce them? How much difference does one tooth either way make? Thanks for any insight.

 

[Ozzie]

I know there are formulas that tell you which speedometer drive and driven gear you need depending on differential ratios, tire size, etc. Regardless of these facts, which direction should one take to increase the speedo cable speed? For example, if my speedo reads 40 MPH and I am actually going 50 MPH, do I need to increase the number of teeth on the driven gear or reduce them? How much difference does one tooth either way make? Thanks for any insight.

Reduce. The difference depends on how many teeth are on the gear. On smaller gears it makes more difference than on larger gears.