Pro Tip: Four Simple Rules to tell if its the Driver or the Chassis

 

The following are some rules to help us determine if it’s you, the driver, or a setup issue that needs to be addressed.

• If the handling issue is inconsistent, that is, it varies from corner to corner, it is most likely a result of driver input.
• If the handling issue occurs at one specific corner, it is also most likely a result of driver input.
• If the handling issue occurs at one type of corner. Such as a carousel, or high speed corner, the issue is most likely a setup issue.
• If the handling issue occurs on left or right turns only, the issue is also likely a setup issue.

Keeping our focus on improving the driver. The driver affects the timing of weight transfer. In previous content (Shock Tuning Demystified), we’ve described how the driver affects HOW MUCH, WHEN and HOW FAST weight is transferred. Being most effective at the use of our available driver inputs, steering, brakes, and throttle can help us minimize speed scrub and attain lower lap times.

 

The transitions are where we need to direct out focus to enable us to begin to identify issues and start to formulate a plan to correct for them.

The transitions are:

• from the completion of straight line braking to beginning turn-in.
• The transition from turn-in to mid-corner and beginning of maintenance throttle.
• And lastly, the transition from mid-corner to exit and application of full throttle.

If handling issues occur during any of these transitions, then we need to look to make some adjustments to the timing and smoothness of our driver inputs.

 

In previous content (Getting The Most From Our Tires), we’ve discussed how everything we do on track involves making the maximum use of our tires available grip. The best drivers are able to keep heat in the tires, maintain a consistent slip angle through all phases of the corner, and care for their tires. Handling issues arise because the available grip from the tires has been exceeded.

• Understeer results when the available grip on the front tires has been exceeded, or there is not enough load on the front tires.
• Oversteer occurs when the available grip from the rear tires has been exceeded, or there is not enough load on the rear tires.

The traction circle, friction circle, or G-circle as it is also called is a tool to help determine has effective the driver, and chassis, is at making the maximum use of the tires available grip.

 

 

In the plot on the left the driver has transitioned from straight line threshold braking loading the tires to the maximum longitudinally, to transitioning to turn-in on a right turn. He or she has moved smoothly off the brakes, began turn in, moving the grip from longitudinal, and now making that tire work laterally. Moving to mid-corner where all the grip is now working laterally helping to move the car along an arc to clip the apex. Doing this and keeping the tire working to its full potential. Before corner entry on straight line threshold braking all available grip is being used longitudinally in slowing the car to the speed we’ve chosen before we begin our turn-in. If steering is applied during this time, the tires have no available grip to turn the car and an understeer condition will result. Turn-in should only begin after we begin to release pressure off the brake pedal. This will free up grip longitudinally from the tire providing for some lateral grip so we can begin to use it to get the car to turn on an arc.

 

The best visualization is to imagine a string is attached from the brake pedal to your hands on the steering wheel. As your feet begin to smoothly transition off the brake pedal imagine a string going from the brake pedal to the steering and turn the steering wheel at the same rate. This will smoothly move the grip being used longitudinally and move that work laterally to help the car turn.

Before corner exit, in mid-corner, all available grip has now transitioned laterally, or should be, if we have any speed and are maximizing the tires available grip. The driver will be on maintenance throttle dabbing slightly at the throttle seeking some grip, and then lifting slightly to get the front tires to bite to help the driver hit his mark. Imagining eggshells on the throttle and not wanting to break them. Too much throttle application here will induce a handling problem, either understeer or oversteer. There is not enough grip available from the front or rear tires to apply longitudinally. Throttle should only be applied as the driver is unwinding the steering wheel. As the steering wheel unwinds, an equal amount of throttle can be added until the steering wheel is fully unwound, and the driver is at full wide-open throttle heading to the next brake zone. Imagine the string from the example before when releasing the brakes. If throttle application causes wheel spin, look to alter your line so you unwind the steering wheel sooner.

To begin to summarize. Moving the steering wheel as little as possible after turn-in will help us find speed. True, we may need some slight corrections, but the perfect corner, and the goal is to not move the steering wheel at all after turn-in until you start to unwind for exit and apply throttle in earnest.

 

Consider turning the steering wheel on entry as a course correction. And fine tuning after turn-in and mid-corner is performed with the throttle. Or maintenance throttle, slight throttle and lift to get the car to travel the arc you’ve chosen.

 

Be smooth with driver inputs. What does this really mean? Minimize abrupt changes with input. Be smooth but deliberate with steering input, firm brake application to build to maximum brake pressure at your chosen brake point, don’t just romp off the brakes but release the brakes smoothly allowing the chassis to absorb the weight transfer.

 

Years ago on ‘Top Gear’ there was an episode where Formula 1 legend Jackie Stewart was brought in to help James May gain several seconds a lap at a track. In this episode Jackie had a great example. If you walk up to someone and punch them on the shoulder, they will fall over. But if you walk up to them and place your hand on their shoulder, then apply pressure, they can anticipate that pressure and lean into your hand press. Link to episode: (jump to 6:40 to see this example) Jackie Stewart helps James May

 

The same is true for your chassis. Help the chassis adjust to your inputs. Finally! The key to speed is finding maximum time on the throttle. This means minimum time on the brakes and moving the steering wheel, both of which … scrub speed.