Determining Gear Ratios
Car settings 8
Find the best gear ratio for the track
From winding sections with consecutive corners to circuits with long straights, various stages make up a race track. Changing the drivetrain gear ratios will allow the engine characteristics to be used in an optimum manner for each stage. Changing gear ratios involves both the gear ratios of the transmission and of the final gear.
For example, when dealing with a series of low- to mid-speed corners, acceleration out of the corners is more important than top speed. As such, you should bring all gear ratios closer together, to make the power band easier to maintain. This is known as a close-ratio gear setting. (Fig. 8.1)
On the other hand, if it is a circuit with a lot of long straights, you can set the ratios for the high gears (such as fifth and sixth gear) so that the car will reach higher top speeds. This type of gearing is referred to as wide-ratio. (Fig. 8.2)
- Fig. 8-1: An example of a close-ratio gear setting. In a circuit with consecutive corners, it helps to focus on acceleration performance by setting the gears closer together.
- Fig. 8-2: An example of a wide-ratio gear setting, with the gear ratios set further apart. On a circuit with long straights, this is a good way to gain higher top speed by setting higher gears.
The gear ratio of the final gear will change the overall character of the transmission. Even with the same transmission, a low final gear will set the car up for more acceleration (top speed will decrease), while a high gear will raise top speed (while lowering acceleration performance). Initially, try changing only the final gear without changing the transmission gear ratios. A good guideline for checking these settings is to ascertain whether your last gear raises the engine RPM to redline at the end of straights.
Let’s look at the selection process for the gear ratios with the Suzuka Circuit as an example (Fig. 8-3). First, calculate the torque which gives the most effective acceleration so as to set the gear ratio for first gear. Next, set the top gear ratio so that the engine will redline just before the 130R of the western straight. (If the car has the ability to drive through the 130R at full throttle, then set it to right before the chicane.) Then set the gear ratio for second gear so that the chicanes and hairpins where the speed drops the most on the track can be cleared in second gear.
Fig. 8-3: An example of gear ratio settings for the Suzuka Circuit. Set the gears so that the lowest speed corners are cleared in second gear, while the top gear is set so that the engine redlines at the end of straights.
Once you have set the reduction ratio of second gear and top gear, set the remaining gears so that the gaps between them are of a constant multiple (with geometric progression). Then test actually driving the car around the track to fine-tune it!
