Rollout

[cheney64]

I've been out of the sport for a while and
since I've been back at the track I've heard the term "Rollout," being tossed around. I know there is a formula for calculating it and that each track has a different # to shoot for. Can anyone give me the formula.

Thanks.

[rvrrun]

Do you mean tire rollout?

That would be the circumference of the tire.

MS

[cheney64]

Tire circumference is part of it, but I think there is more, I just don't know what.

Thanks

[BBalak]

Roll Out is calculated by using the following formula:

[Tire Diameter x 3.1428/(Teeth in Spur Gear/Teeth on Pinion Gear)] / Gearbox Ratio

So, lets say you have an HPI Pro 2 Touring car. A Pro 2 has a gear box ratio of 2.14. Most touring car tires have a diameter of 65mm (Measure your tires to be accurate). So, you would mulitply 65 X 3.1428 = 204.268. If you have a 122 tooth spur and a 35 tooth pinion, you would take 122/35 = 3.485. Next, you would divide 204.268 by 3.485. That = 58.613. 58.613 / 2.14 = 27.389. So, your rollout would be 27.389mm

Hope this helps.

Bryan


[This message has been edited by BBalak (edited 01-19-2001).]

[SteveP]

Balak is on the money, and the precision doesn't really matter, but the factor for calculating tire diameter is 3.141592.... or Pi. It doesn't really matter because were talking about a difference in the thousandths, but I wanted to be technically accurate. http://www.rccaraction.com/ubb/biggrin.gif

[This message has been edited by SteveP (edited 01-19-2001).]