Both oversteer and understeer can happen as a result of the slip angle difference between the front and rear wheels of a vehicle. If that sounds confusing, read on.

Before we go into the difference between the two, let’s define what slip angle means. Measured while the car is turning, the slip angle is the angle between the direction a vehicle is traveling and the direction that the wheels are pointing. From an engineering perspective, the scientific calculations that determine slip angles are complicated. If you are interested in understanding the mathematical formulas that comprise this measurement, this article from ScienceDirect is highly informative.

The differences between understeer and oversteer are easier to understand by considering each individually. The following commonly asked questions and answers will help with that.

Understeer Q&A

What Does Understeer Mean?

Understeer is a condition where your car turns less sharply when cornering than you (the driver) had intended. In other words, it’s a lack of your car’s front-end responsiveness when cornering.

When understeer happens, the front tires begin to slip first when cornering. Because the rear tires have road surface grip while the front tires have lost grip (slipping), the vehicle will turn less than if all four tires had grip. This physical effect is known as understeering.

Front-wheel drive vehicles tend to be more prone to understeer because the front tires must handle both the lateral cornering force and engine torque. As a result, the front tires approach their traction limit more rapidly.

What Does Understeer Feel Like?

The sensation of understeer is very subtle. You will likely feel a slight steering wheel judder. More importantly, you will visually sense that your car is veering outwards and away from the road-cornering center.

What Causes Understeer?

Turning the steering wheel abruptly, or just too much for the vehicle’s speed versus the available wheel grip, exceeds the front tires’ traction. This forces the front of the vehicle to slide wide across the road surface in an understeer scenario.

While understeer happens as a direct result of driver input, several other factors play a part. Weight distribution and suspension geometry affect measured understeer gradient. Power distribution, brake bias, and front-rear weight transfer also affect which wheels lose traction first in many real-world scenarios. In addition, causes of understeer can include:

• Incorrect or variable tire pressure between the front and back wheels. 
• Worn steering system components.
• Bad wheel alignment, especially if the camber is off.

How Do You Correct Understeer?

In competitive motorsport, racing drivers will often reduce understeer by keeping the brakes applied until the last second when cornering, to place more weight over the front wheels through centrifugal force. 

In general, extreme understeer in most passenger cars can be corrected by mechanical adjustments, such as the following:

• Reducing rear tire pressure.
• Using softer tires at the front of the vehicle.
• Adjusting front-end wheel alignment. 
• Softening the anti-roll bar or front springs.
• Increasing front-end downforce (if the car has aerodynamics fitted).

What Should You Do In An Understeer Situation?

Inexperienced drivers instinctively turn the steering wheel even harder into the corner when their cars are in an understeer situation. As you now know, increasing the steering angle increases the cornering force, causing the front tires to lose traction completely. What you should do in an understeer situation is to ease off the accelerator while gently applying your brakes. By doing so, more weight is transferred to the front tires to increase road surface grip.

Oversteer Q&A

What Does Oversteer Mean?

Oversteer is the tendency of a car’s back-end to slew out (fishtail) when cornering. Rear-wheel-drive cars are more prone to oversteer. The reason is that the back wheels have to handle both the lateral cornering force and engine torque, resulting in the rear tires reaching their traction limit more rapidly. Oversteer can be dangerous as it can lead to the car spinning out of control.

What Causes Oversteer?

The action of oversteer is a common factor in rear-wheel-drive vehicles. It happens when the driver applies more throttle power than the car’s tires can handle when cornering, resulting in tire slip. In other words, the car’s tires push in opposing directions, causing the rear-end of the car to swing outwards.

What Does Oversteer Feel Like?

Oversteer is very noticeable. You will sense the centrifugal force through your body as your car’s rear-end begins to slip outward. In extreme cases, the car will spin out of the driver’s control.

What Should You Do In An Oversteer Situation?

Inexperienced drivers instinctively tend to apply brakes when the car begins to oversteer. However, braking hard while cornering aggravates the situation, causing the rear tires to lose more traction. The correct reaction is to reduce the steering angle gently while easing off the accelerator. 

What Is Snap Oversteer?

Snap oversteer is a term that refers to the action when the driver lifts the car’s throttle midway through a corner, also known as lift-off oversteer. Inexperienced drivers often cause snap oversteer when trying to reduce speed, after braking too little or too late.

Conclusion

If your car tends to understeer and oversteer, the best solution is to consider upgrading to a newer model. Many modern cars come with computerized components that sense understeer and oversteer characteristics. These components automatically compensate by adjusting acceleration, braking, and even shock absorber suspension, to safely counter the effects of understeer and oversteer.

Most used car dealers have a wide range of newer model cars in stock. A prime example in Jersey City is New Jersey State Auto. We offer an expansive and comprehensive selection of used cars to cater to every driver’s budget and needs.

You can also sell your car to New Jersey State Auto, even if you aren’t planning to buy a replacement car. The online car valuation is a nifty tool to get an instant appraisal. If you’re happy with the valuation, all you need to do is bring your vehicle to the dealership in New Jersey, and you’ll get a check on the same day.