>I have a question about odo in general that I never really
>understood or got an answer to, how does the odo display
>accurately by measuring turns of the wheel or the driveshaft
>when there is so much wheelspin envolved?
Short answer: It doesn't, which is why experienced codrivers are in demand
.
Longer answer: It doesn't, but there are a number of ways to deal with it. In a 2WD car, the odo can run off a non-driven wheel, which is a lot more accurate (although lfb can affect that). In a 4WD car, the wheelspin tends to be evened out a bit, making the error less. In either case, the codriver will likely adjust the factor on the odometer to allow for some amount of wheelspin. 15% is a good 2WD ballpark to start with, but it may take a stage or two to get something that works accurately, and will be dependent on conditions. A 4WD adjustment is likely less (5-10%). Also, calling to incremental distances (rather than overall distances) can help alleviate the effects of wheelspin as the error will be less on the incremental since it is only from the last instruction. The bottom line is that an experienced codriver will adapt the factor(s) to the car and driver, and can be very accurate. This works even better after a team has worked together for a couple of events.
Adrian
