Information About Understeer

Thread Starter #1
Sep 16, 2009
Understeer occurs when traction is lost at the front wheels while cornering, forcing you wide on a bend despite applying the correct steering angle . When viewed by an observer, this action looks as if the driver has applied insufficient steering lock (or under steered). If you're car is understeering, you're scrubbing off speed and missing the optimum line, so it's not a quick way to take a bend!

Picture of Understeer

Understeer happens due to-:
1) Accelerating into a bend
2) Braking into a corner
3) Driving into a corner too fast
4) Low traction conditions on the corner such as ice or oil

Symptoms of understeer-:
Light steering
Drifting towards the outside of a bend
Possible tyre noise from the front wheels

Correcting Understeer-

1. Accelerating into a bend

Picture the scene, you're on a roundabout about to take the third exit but you think it might be a laugh to go round again. You keep accelerating through the bend and find that the car has a tendency to run wide. The available grip at the front wheels is being used in equal amounts to accelerate and to steer. As you accelerate more, you have less grip to steer – simple. So, reducing either of these inputs will correct the understeer.

This is the easiest form of understeer to correct, and a slight, smooth reduction in power will free up more grip (with the added benefit of a forward weight transfer), and a small corrective input to the steering will get you back on line.

Note: If you're driving a rear wheel drive car and you accelerate aggressively mid corner you're more likely to cause oversteer.

2. Braking into a corner

When you apply the brakes, most of the braking effort is exerted on the front wheels. So if you're braking into the corner you're using most of your available grip trying to scrub off speed. If you then exert some steering lock, the addition of these lateral forces on the tyre can cause the limits of grip to be exceeded. So, correcting understeer seems simple - stop trying to turn the corner (a better plan might be to get your braking out of the way while you're in a straight line). However, if you happen to be in the middle of a bend as your car starts to understeer, continuing straight on might not seem like the best plan. An alternative strategy could be to reduce your braking effort, freeing up more grip for steering and hopefully allowing you to take the bend successfully.

3. Driving into a corner too fast

If you have attempted to take a corner too fast, have turned the steering wheel, and find yourself running wide, you my friend are in a spot of bother. But before you close your eyes and hope for the best, all may not be lost. You've exceeded all of the available grip, yes, but it may be possible to actually increase the level of grip by the slightest, smoothest dab on the brakes. "The brakes?!", I hear you shout, "but surely that is adding to the demands of the tyres, not reducing them?". This is very true, but if you're not totally out of control by pressing the brakes you're causing the weight to transfer to the front, and thus artificially increasing the levels of adhesion at the wheels. This may, however, not work. The moral is to enter the corner at a slower speed, then get on the power early on the way out.

4. Low traction conditions

If you've entered a corner at speed and notice a sudden reduction in traction due to oil, black ice or a banana skin, the best course of action (in the immortal words of Douglas Adams) is to consider how lucky you are that life has been kind to you so far.

If life hasn't been kind to you, consider how lucky you are that it won't be bothering you much longer.

Alternatively, be careful, think about the conditions and adjust your entry speed accordingly.

How to Avid Understeer

  1. Be smooth
  2. Don't enter the corner too fast
  3. Don't brake (hard) into the corner unless you are using trail braking.

Simple modifications to make a car less prone to understeer

1)Reducing the front tyre pressure
2)Softening front springs or anti-roll bar
3)Use softer front tyres
4)Increase front down force (if aerodynamics fitted)


Sep 18, 2009
This is great info kartik.
In India, most of the cars have light steering, and strangly most of the people like that.
Good cars (or say more stable cars) does have not so soft steer, and this is great to have for enthuziasts.
Aug 22, 2009
Reducing the tyre pressure might bring some other tyre and mileage related problems.

Turning with a lower gear will give you more traction.
Oct 15, 2009
Actually how to feel this understeer??? i hav gone into curves at 100kmph but my car was stable enough.
Its not a stability problem. To feel understeer, find a deserted corner, and set a line which u intend ur car to follow thru out the corner. Enter the corner on this line, atry to keep ur car on the line, u'll find thet your car will go wider than the line u intended. This is known as understeer.

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