Understeer Question...

[sammus]

Bit of a newbie question, I guess but I won't learn if I don't ask

My understanding of understeer is when the rear wheels make a smaller arc than the fronts in a turn... and of course oversteer the opposite, when the rear wheels make a larger arc than the fronts in a turn.

I can't think of a way you would understeer in a, for example, right turn, without oversteering to the left beforehand.

Is the above correct? If not how do you understeer?

Any help would be appreciated...

[Endorean]

Well think of it this way....

You approach a right hand corner at 60Kms', You slow down and start to turn your steering wheel to the right, In a neutral steer situation (no under or over steer), as you turn the steering wheel the car would follow the path of the front wheels and you would go into corner and exit normally.

With understeer, the car doesn't follow the direction of the front tyres and continues to go straight ahead or there might be a delay in turning.

From a driver's point of view, you would turn the wheel and it feels like nothing is happening because the car is still going straigh ahead.

Hope that helps, I may have just confused you more =)

[redline2003]

the car trying to go straight ahead when u turn the steering wheel to corner, usually when entry speeds exceed the limits of tyre adhersion. mostly happens in fwd/4wd, it can b pretty scary but only happens when u r giving it to it ie dropping clutch at 5000rpm before corner in 2nd gear, in the wet it can b pretty dangerous

[franks]

i'll explain it even easier....

* understeer sux, oversteer rules!

* understeer puts a frown on your face, oversteer puts a smile on your dial (and

maybe some poo in your pants)

to graphically demonstrate...

this is understeer, steering wheel at full lock, car nose pointing in direction of travel before turning steering wheel:

this is oversteer:

...and from the reverse angle:

[sammus]

Ah gotcha. So high entry speed is what does it...

Those are awesome shots... demonstrate it well. I like the skirts on that r34.

Thanks guys.

[rb26dett]

there are other factors which will induce understeering...like backing off the accelerator n braking during cornering

[Steve]

Hmm, I have found that braking too hard into a corner - or rather too late, will increase the likely hood of oversteer. Just like if you back off too quickly during oversteer. Too much weight transfer to the front wheels, or just enough if you are into that sort of thing:D

[Mick Trainer]

I think the photos demonstrate it very well but from some of the comments greater explanation is needed.

Understeer is as the title suggests when the car does not turn enough thus "understeering". The front wheels have lost traction and thus the front of the car pushes through the corner and the car does not turn in. It is caused generally by too higher speed on turn in or by to much power being placed to the front wheels in a FWD or 4WD car and thus once again pushing the car through the corner. The photo of the 33 clearly shows that the front wheels are turned in hard but the car is pushing forward and not turning at the same rate as the wheels. Look at the car's track/road position. It is right out on the outside of the corner no where near correct turn in point as it has pushed through the corner as it has not turned enough. Once understeer has commenced backing off the throttle to reduce speed is the best avenue to counter this problem (taking some lock off and gentle braking can also be an option depending on the levels of understeer and the corner etc).

Oversteer as the name suggests is where the car turns to much, bringing the rear of the car to a slide turning the car on a greater angel to that which is required for the corner. As seen in the photos of the 34 the cars rear is turned pushing to the outside of the corner as the car is turning too strongly. This time it is the rear that has lost traction. Oversteer is caused by too much acceleration when exiting a corner. Backing off the throttle and applying counter steering (turning into the slide) is the best way to counter this condition.

Now if you do not understand nor feel comfortable playing around with these two areas and you drive performance cars such as the skylines I think that an advanced driving course is very much a necessity for you. Understadning and feeling comfortable when these things occur is a much for any performance car driver.

Mick.

[Mighty Highlights]

Of course too much power on the exit of a corner will only oversteer a rwd car. If you have a fwd too much power will cause the front tyres to exceed their levels of grip. There is not enough grip in the tyres to turn the car, as you are using up some of the grip to accelerate. Something has to give - either wheel spin, or the car understeers.

That wasn't very clear. !

Basically, if you run out of grip on the steering wheels - then you cant steer anymore so the car moves in the direction of the momentum i.e. straight.

-- If you regain grip on the front wheels - back off the power/ slow down then the front end will start turning you again, then the rear may run out of grip - causing an oversteering situation.

If you run out of grip on the rear tyres the car moves with the momentum again - if you are going around a right hand corner then the rear will swing around in a clockwise direction.

-- If you regain grip on the reer wheels - back off the power then the rear end will start pushing the car foward (as they only go straight - ignoring 4ws) , then the front may run out of grip - causing an understeering situation.

To run out of grip all you need is too much power or to much speed.

More confusing? well bad luck, that the best I could do Go to a track day.

[Warpspeed]

Haha. There is an old saying.............

Understeer is when the driver wets his (her) pants.

Oversteer is when the passenger wets their pants.

[Amaru]

I dont believe backing straight off in an oversteer situation is good. If you just jump off the throttle it will cause the weight of the car to transfer to the opposite side (what you feel when the car "snaps back"), and more often than not in a RWD car with some balls will cause the car to spin. Better option is to slowly move off the throttle but always keep the car accelerating/powered and control it with the steering wheel to pull it back in line.

But thats just my opinion

[franks]

Haha. There is an old saying.............

Understeer is when the driver wets his (her) pants.

Oversteer is when the passenger wets their pants.

hehehe, i like this saying

[Mick Trainer]

I dont believe backing straight off in an oversteer situation is good. If you just jump off the throttle it will cause the weight of the car to transfer to the opposite side (what you feel when the car "snaps back"), and more often than not in a RWD car with some balls will cause the car to spin. Better option is to slowly move off the throttle but always keep the car accelerating/powered and control it with the steering wheel to pull it back in line.

This is very true. I should have explained this part as well.

Mick.

[Duncan]

Or anther way to explain.

Understeer is when you see what you are about to hit

I think you need to be careful recommending that you don't back off when you get unexpected oversteer. While this is correct in the most technical sense, if you didn't see the oversteer coming you probably don't have the experience to catch the tail when it swings back again.

When you head out to a race track, check out the skidmarks on the exit of the corner....they are always heading back to the inside of the track....a car was oversteering, the driver kept the boot right in...and the tyres regained traction and shot them into a wall.

Probably the safest idea is Mick's original suggestion, steer into the slide and back off slowly.

[Warpspeed]

I believe a lot also depends on the circumstances and how fast you are going.

If its at low speed in the wet, and you suddenly hit an oil patch or something turning at an intersection, or going around a traffic island, I would think backing off pretty smartly might be best, especially if you have an LSD and both rear wheels suddenly break traction.

On a fast sweeper in the dry at high speed, if you feel the rear starting to go a bit wide, I think you might be a bit more cautious, and just slowly ease off.

Both are an oversteer condition, but the situations are totally different.

[Mick Trainer]

No question that the circumstance in which the O/S comes will alter the best avenue of defence and thus action to be taken. This is why a driver must be famialiar with them to the point where he/she is comfortable to drive a car through such conditions without panicing.

Mick.