Originally Posted by
Bsthetech
New to 1/12 pan cars...I'm playing with a gear ratio calculator. What do I put for "Trans Ratio" seeing as it's just a spur and pinion? 1.00?
Yes, but...
Internal ratio is 1, but since foam tires can vary in diameter, rollout is what you need to gear toward, as it will take the tire diameter into account.
Rollout = ((tire diameter * pi)*pinion)/spur
So if you know the rollout you're looking for and trying to figure out which pinion to use, it's
Pinion = (Rollout * Spur) / (pi / tire diameter)
There's other rollout calculators online, or a spreadsheet is easy to make for your own use when you know what your targets are.