Originally Posted by shipwama
ok so the trakc is carpet indoors, i would say it isnt overly large and flowy, but then again it isnt tight, i would say it is in the middle, a little more on the tighter side. as for tires, i have not done anything to them but mount them so they are the stock size, which im not sure what that is
Okay, not looking to frustrate you and I'm not trying to give you a hard time, but if you can't measure the diameter of your tires it's impossible to give you a suggestion on gearing.
All you're telling us is that they're out of the box Jaco tires,that doesn't help much... I've had two sets of jacos (same rim, same compound) come out of the box different enough in diameter to need different gearing. Add to that the fact that Jaco has made and sold tires on several different rims, and we're simply unable to guess at what you have on the car.
If this is any help, I'll give you the formula for determining rollout. Rollout is the distance your car will move forward for each revolution of the motor.
To calculate rollout, you first multiply the rear tire diameter by 3.14 to get the circumference. That's the distance the car will move forward for one revolution of the tire. Now to determinie how far the car will move for one revolution of the motor, you divide the pinion by the spur, and multiply THAT result by the circumference of the tire... for example, if your tire is 1.8" in diameter, and you're running a 30 tooth pinion with your 94 spur, you'd multiply 1.8 x 3.14 to get 5.652 (that's your tire circumference) now divide your piniono by your spur, 30 / 94 to get .319. Now multiply 5.63 by .319 to get a rollout of 1.79 inches.
That's fine, but you don't need to find your rollout, you need to figure what pinion to run... to calculate that, first you need to know what a good rollout is to be running. For a 1/12 car ono a medium size carpet track, I'd be thinking somewhere around 1.65 to 1.7 inch for a monster stock motor like you're running. To get the pinion, you multiply the spur by the rollout you're trying to get (in your case, a 94 spur and 1.65 rollout) to get 155.1 Now, divide that by your tire's circumference (for example, let's say your tire is 1.8 inch in diameter like the last example) Multiply 1.8 by 3.14, you get 5.652, then divide 155.1 by 5.652 to get 27.44 since you can't get a 27.44 pinion, you'll want to run either a 27 or a 28.
Of course, you'll need to measure your tire diameter, unless they're 1.8 inch like in this example, these numbers won't be appropriate for you.
Hope that helps...