Motorsport Wheel Alignment: Understanding What the Car Is Doing
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Understanding What the Car Is Doing
03.56
| 00:00 | - Before we can make any informed adjustments to our alignment, we need to know what problems the car is exhibiting so that we can formulate a plan to help improve it. |
| 00:09 | This of course can be tricky for novice drivers as a lot of this will revolve around feeling what the car is doing, so that we know where to focus our attention. |
| 00:17 | Let's start by defining the terms we need to use when talking about the handling of the car. |
| 00:23 | These terms include understeer which is where the car tends to want to continue in a straight line and we need to use more steering lock in order to get the car around the corner. |
| 00:32 | This is probably the most common handling trait you'll find in production cars, particularly front wheel drive cars since it's deemed to be relatively safe and correcting an understeering car is a natural reaction for most drivers. |
| 00:46 | Next we have oversteer which is where the rear of the car becomes loose and the car turns further into into the corner than our steering input asked for. |
| 00:54 | Oversteer is a little more complex to deal with because unlike understeer, correcting oversteer requires some proactive driver input in terms of applying opposite lock to prevent a spin. |
| 01:06 | In general, when we're trying to analyse the handling balance of the car, it's easiest to break it down into four separate areas so that we can analyse them one at a time. |
| 01:16 | Broadly we're going to consider the braking stability, the turn in, the mid corner and finally the corner exit. |
| 01:24 | So let's deal with each of these in turn. |
| 01:27 | Starting with braking stability, what we're looking for is a car that will pull up nice and straight when we're braking hard. |
| 01:34 | We want to be sensitive to the car wanting to dart from side to side or to potentially swap ends while we're braking hard, as these issues could indicate that we've got problems with toe or excessive deflection of one of the bushings. |
| 01:47 | We do need to keep in mind however that if we're braking hard, while we're trying to turn, this can easily result in the rear of the car wanting to slide into oversteer due to some of the weight transfer present, so some perceived issues here can actually be diver influenced. |
| 02:04 | We will deal with driver influenced handling issues in the next module though. |
| 02:08 | Next, we'll deal with corner entry or turn in which is the period where we're releasing the brake pedal and beginning to turn the wheel into the corner. |
| 02:17 | What we want here is for the car to track our steering input sharply and consistently without understeer or oversteer, making it easy for us to accurately reach the apex of the corner. |
| 02:29 | The mid corner portion is usually quite easy to confirm the car balance in, particularly through a long corner, since we'll have plenty of time to adjust the car speed and find the limit of adhesion. |
| 02:40 | Again, we're trying to feel if the car tends to oversteer, understeer or be relatively neutral here. |
| 02:47 | It's important to make smooth adjustments to the throttle input here, as large changes can easily upset the balance of the car, invoking understeer or oversteer. |
| 02:57 | Lastly, we need to consider corner exit, which is the portion where we're beginning to apply power as we wind off the steering lock. |
| 03:05 | What we're trying to notice here is how easily the car can accept throttle, or to put it another way, how quickly we can get back to full throttle. |
| 03:14 | When we're considering the handling balance of our car, we do need to be a little realistic as to what we can expect to achieve. |
| 03:20 | For example, if we have a powerful rear wheel drive car, then hoping to get to full throttle out of a slow speed hairpin, is going to be pretty futile. |
| 03:29 | We also need to understand that the handling balance of the car may be different in low speed corners compared to high speed corners so some level of compromise is always essential. |
| 03:40 | Developing the suspension and alignment is also an iterative process. |
| 03:43 | In between driver feel, the stopwatch and datalogging if we've got access to it, we can start to see if our changes are moving in the right direction. |
