oversteer / understeer

[Louis B.]

I just made a quick search on this forum but didn't find answers to my interrogations on what might be pretty basic in car racing.

Anyhow, unafraid of making a fool myself (again), here are my questions on the topic:

We often hear drivers complaining about their car oversteering and/or understeering (indeed, JV recently complained that his car was understeering in some turns while oversteering in others). What are in fact the causes of the problem? Is this truly a problem with the car/its set up/braking balance/etc. or mostly an easy excuse for a driving mistake?

Before answering, a few clarifications may be appropriate. My understanding of both phenomena is that a car is oversteering when its rear end is sliding out while it is understeering when the forward end is not responding to a change of course of the front wheels. Am I correct with that? Does this mean that a perfectly balanced car would slide sideways if pushed too hard in a turn (i.e both rear and fore ends would slide sideways altogether at the same time)?

Motor racing experts and quasi-experts of 10/10ths, please enlighten me!

[Peter Mallett]

Your definitions are correct.

As to the dynamics I haven't a clue. In simple tin tops understeer can be caused by too much spring on the front and or too little spring on the rear, whilst oversteer is generally due to the rear end being set up too hard.

Then you get ride height which also needs to be factored in.

Then again either condition can be caused by the driver. F'rinstance if you go too deep into a corner then apply the brakes, you'll induce oversteer because the car is already turning as you hit the brakes. This technique is employed by racers of front drive cars.

OTOH if you fail to slow the car before turning in then you'll get understeer which from experience soon has you heading for the scene of the accident.

Now, you mentioned JV so I suspect its driver induced.

BTW. If you scroll down to related threads you'll find at least one topic discussing this.

[Alan Cherry]

Originally Posted by Louis B.

I just made a quick search on this forum but didn't find answers to my interrogations on what might be pretty basic in car racing.

Anyhow, unafraid of making a fool myself (again), here are my questions on the topic:

We often hear drivers complaining about their car oversteering and/or understeering (indeed, JV recently complained that his car was understeering in some turns while oversteering in others). What are in fact the causes of the problem? Is this truly a problem with the car/its set up/braking balance/etc. or mostly an easy excuse for a driving mistake?

Before answering, a few clarifications may be appropriate. My understanding of both phenomena is that a car is oversteering when its rear end is sliding out while it is understeering when the forward end is not responding to a change of course of the front wheels. Am I correct with that? Does this mean that a perfectly balanced car would slide sideways if pushed too hard in a turn (i.e both rear and fore ends would slide sideways altogether at the same time)?

Motor racing experts and quasi-experts of 10/10ths, please enlighten me!

At the risk of being shot down by every other racer on this forum :-
understeer ( or pushing ) is going through a hedge forwards.
Oversteer ( or loose ) is going through a hedge backwards,
Understeer is when you turn the front wheels,but due to slip angle the car does not turn to the same degree - usually quite safe ( but timewasting) unless terminal, as you think I'm not going to make this bend, and just wind on more lock and scrub even more speed off.
Just driving a saloon there can be so many reasons for understeer/ oversteer - god knows how they cope when they've got adjustable aerodynamics as well !

[Alan Cherry]

OOPs Sorry - slip angle is the difference between what angle the wheels are actually pointing, and the direction in which they are travelling !

[Peter Mallett]

BTW. Martin Brundle used to demo cars before a race. He once described the Jordan as perfectly balanced because the front and the rear slid in unison and indeed this is what you want because then you can throw it into a corner knowing that the suspension is working to its limit and you can control the car either on the throttle or (gently) the brakes.

[Marbot]

JB was a little non-plussed in Spain when he tried to correct understeer (or 'push' if you're across the pond) in qualifying by tuning in more front wing to push the front of the car harder into the track in order to create more front grip.It didn't work.

Many drivers acoss the 'pond' complain vehemently of having a 'loose' (oversteery) back end!

Or understeer is when you can see the accident coming and oversteer is when you can't.

[Knowlesy]

JB actually had to take front wing OUT to reduce the understeer, which is baffling. Something to do with the deep spoon section and the increased corner speeds this year, or somesuch craziness....

[Louis B.]

Thks for your explanations

Originally Posted by Peter Mallett

Then again either condition can be caused by the driver. F'rinstance if you go too deep into a corner then apply the brakes, you'll induce oversteer because the car is already turning as you hit the brakes. This technique is employed by racers of front drive cars.

OTOH if you fail to slow the car before turning in then you'll get understeer which from experience soon has you heading for the scene of the accident.

Am I correct though that, if it is induced by the driver, then we should be talking of a driver mistake, style or technic rather than oversteering / understeering of the car? I did not notice that this year but I used to note that MS was apparently enjoying "oversteering" his car (sometimes using the kerbs to stop the slide of the back end).

Originally Posted by Peter Mallett

Now, you mentioned JV so I suspect its driver induced.

Nope. It's the chasssis' fault, unable to get heat evenly to the tyres.

[Knowlesy]

Originally Posted by Louis B.

Am I correct though that, if it is induced by the driver, then we should be talking of a driver mistake, style or technic rather than oversteering / understeering of the car? I did not notice that this year but I used to note that MS was apparently enjoying "oversteering" his car (sometimes using the kerbs to stop the slide of the back end).

It can be all three. A mistake perhaps.

Oversteer is sometimes induced to negate the effect of understeer and vice-versa.

Others just have it as a style....Kimi for example likes an understeery car, whereas JPM likes an oversteery car.

[Louis B.]

Originally Posted by martyn bott

Or understeer is when you can see the accident coming and oversteer is when you can't.

... unless, obviously, you are looking at your rear view miror at that very moment.

[Louis B.]

Originally Posted by knowlesy

whereas JPM likes an oversteery car.

especially during the warm up lap... Sorry, I could not resist.

[Knowlesy]

*yawn*

[elspethhardie]

Thank you Louis B I've been wanting to ask this for ages but keep forgetting to do it!

[Louis B.]

Originally Posted by shiny side up!

Another common phenomenon is this: The car is understeering, but the driver reports oversteer.

I know, seems crazy... but it happens all the time ( although one would think not such a problem with F1 caliber drivers... ).

This is caused by the driver overcompensating for one or the other...

Thks. This may explain the apparent contradictions between what we see and what we sometimes hear on TV from the drivers or TV commentators.

[Peter Mallett]

In an effort to keep this on Formula 1 I've moved the off topic posts to this thread. http://tentenths.com/forum/showthread.php?t=83774

[Peter Mallett]

Originally Posted by Louis B.

especially during the warm up lap... Sorry, I could not resist.

Yep. Alain Prost was still kicking himself for that Imola incident when he retired at the end of '93.

[Kirk]

In reference to Monaco. Mainly due to the one-tyre rule in 2005, there were several cars with badly worn rear tyres. The most obvious being Fisi and FA, causing them to slow significantly later in the race. I would assume that the rear tyres wearing faster than the fronts would cause loosen the car or cause oversteer, which to most F1 drivers is not that bad to some degree. But the Renaults pace suffered last year, Fisi faded fast and FA just barely hung on. This may not be such a factor this year but if there ever was a track where you can get away with a less than balanced car it is at Monte Carlo. Of course, assuming you keep it on the track.

[Louis B.]

I also note that, so far, no one other than me (I was only guessing), mentionned braking balance as a possible cause. Is it because one should not use the term oversteering/understeering in such a situation or is this just an oversight (or undersight ) from the pundits of this forum?

[Kirk]

Originally Posted by Louis B.

I also note that, so far, no one other than me (I was only guessing), mentionned braking balance as a possible cause. Is it because one should not use the term oversteering/understeering in such a situation or is this just an oversight (or undersight ) from the pundits of this forum?

Two different animals as far as I'm concerned. Though too much brake, on either side of the equation will cause instability in corners.

[hgmonaro]

Oversteering cars are generally good to watch/drive but usually slow, loosing grip and drive just when you want to be charging towards the next corner. Understeering cars are boring to watch and cause anxiety due to the 'am I going to make it around this corner' factor. A truely neutral car is probably very rare due to the different corners on a track and the desire to have a car one can trust. A little bit of understeer is probably more consistant. Witness the way FA applies full lock as he enters some corners, he just cranks the wheel over and assumes (which it seems to do) that the car will get around. 110% commitment. The different manner in approaching a corner, whether during brakeing or under power (say a bend after a slower corner) can make a huge difference to what happens due to the weight transfer.

Guess if it was easy to balance all the factors... they'd all go like Renaults!

[Snrub]

F1 cars are rearward weight biased, but some will have more weight in the rear vs. the front. Eg. A few years ago the Sauber was considered to be the best balanced car on the grid, but that didn't mean that it was the fastest chasis. Typically a car with more rear weight than average will have more oversteer and conversely one that has more front weight than average will have more understeer. There are so many factors with an F1 car that everthing is a compromise.

Usually under/oversteer is down to setup. Sometimes the basic suspension/aero design make a car more prone to under/oversteer with a fast setup. Sometimes teams dial out some of those tendancies with the setup. The car might be easier for a driver to drive, but it may produce lower lap times. Race setups must have a certain compromise in raw speed for drivability.