Calculate gearing changes based on windspeed?

[Kometes]

Hi All,

I'm looking for a set of equations to allow me to calculate gearing changes based on a known tail/head wind speed, anyone got any starting points? 4 speed transmission and a fixed engine output.

Cheers,

 

[xxChrisxx]

In what context? Road car, racing, etc? The changing of actual ratios in the box or shift points?

 

[Kometes]

Race car and changing the actual ratios. For example, car has w,x,y,z gear ratios in so that the engine is hitting the limiter at the end of a straight, if it then gets a 5km/h head wind I'd like to be able to work out how many teeth I'd need to go down on the final gear (z).

 

[mender]

Since you're mainly fighting aero drag but hopefully still accelerating (depending on the class and track), your potential top speed will be down by about the same amount as the head wind. Knock off half the percentage difference (200 km/h vs 195 km/h for example) and start with that.

Personally, I'd be careful about changing final drive ratios to compensate for somewhat unreliable wind conditions at the risk of messing up corner exit performance at other places on the track. Unless you have extremely long straights, you might end up being slower.

 

[Kometes]

Thanks for the reply Mender. It'd mainly be for top gear and there's few corners where you're maxed out in top gear so it should be fine.

 

[mender]

Sounds like you're talking about changing the ratio of fourth gear and not the final drive ratio (diff), right? If so, ignore my comment!