replaced speedometer driven gear with recommended 40 tooth and still not accurate...
A big Thank you to @moparmat2000 for this chart. I want to point something out; On the rear tire height axis, find the dividing line between 26 and 27, and follow it down. Notice that the tooth count is always ~10 times the gear ratio. So if you have a 26.5 tire, and you know the rear gear, then you just have to multiply the gear ratio by 10.
But if you don't have a 26.5, then you just convert the difference to a percent and add/subtract it. Knowing this, you can now commit every number on that chart to memory with one simple rule.
Using a 26.5 tire, just multiply the gear ratio by 10.
So in your case that is 3.91 x 10=39.1 teeth. Your tire must be slightly smaller than 26.5, for Mancini to recommend 40. the math says 39.1/40 x26.5= 25.9 tall.
A big Thank you to @moparmat2000 for this chart. I want to point something out; On the rear tire height axis, find the dividing line between 26 and 27, and follow it down. Notice that the tooth count is always ~10 times the gear ratio. So if you have a 26.5 tire, and you know the rear gear, then you just have to multiply the gear ratio by 10.
But if you don't have a 26.5, then you just convert the difference to a percent and add/subtract it. Knowing this, you can now commit every number on that chart to memory with one simple rule.
Using a 26.5 tire, just multiply the gear ratio by 10.
So in your case that is 3.91 x 10=39.1 teeth. Your tire must be slightly smaller than 26.5, for Mancini to recommend 40. the math says 39.1/40 x26.5= 25.9 tall.
