Understeer vs oversteer

[Marst]

Dear Alls,
Please advise me, from technical point of view, which one is more dangerous, understeer or oversteer?

[sharkie17]

oversteer.

Most ALL car manufacturers dial in toward understeer. (Manufacturers seems to think that oversteer harder to handle for a Joe Driver)

[Alic01]

I saw a good post on here with regard to this subject but i cant find it. The basis of the post was this:

With understeer you dont turn leave the road and hit a tree.

With oversteer you spin round 180 and leave the road and hit a tree.

But... with oversteer you dont see the tree that kills you.

I think sharkie is right, almost all road cars are set up with understeer. It is generally only supercars and overpowered / unbalanced cars which encounter oversteer. I know the 3.5 litre 250HP Alfa 147 is almost undrivable due to power oversteer even in 1st gear, that can make turning out of your road an ordeal!

[tempest]

Er... wouldnt that be power understeer? Given that it is front drive, putting the foot down in 1st gear causes understeer, oversteer occurs in a front drive car when you go into a corner to fast and lift off. Power oversteer occurs in rwd, but in most cars you still need to be going fast enough to get it unsettled. (Have done this many times)

To answer the original post, understeer is far easier to predict and correct for Joe Driver, most people (or at least the crap drivers in aus) tend to over-correct when they get into an oversteer situation which just makes things a whole lot worse.

[Alic01]

Tempest, you may well be right, all i know is that i didnt buy one because the back end is twitchy as hell!!

As for oversteer and understeer in an F1 car, a Michelin engineer said on Sunday that at Hockenheim they design the tyres to provide a little bit of understeer on the qualifying lap because the track is 'rear limited'.

If the car was biased towards oversteer the degredation of the rear tyres would be increased even further resulting in useless rear tyres and fine front tyres.

In a race situation understeer generally damages your lap time due to missing of apex's and you could lose the confidence to overtake or maintain your position. Where as it is possible for oversteer to result in a spin which is ultimately more costly and could even end the race.

The worst scenario is what Martin Brundle says Minardi suffer from which is understeer on the way into a corner and then oversteer as they put the power down to exit the corner.

I think the real answer is that it is entirely driver prefference, some drivers like a car that oversteers and then they control the rate of oversteer, others like a little understeer.

[Steven]

hmm, don't really think there is a big safety difference though, both just need a different type of correcting. I think correcting understeer when you go into a really fast corner is simpler, yet you can't do that much yourself compared to oversteer.
When you go out understeering, just brake and hope you get grips again on the front wheels.
In case of oversteer, brake some and steer back, you may not get the corner very fast, but the chance you stay on or close to the track is quite big.

This actually remembers me of Alonso in France, that guy had really lots of understeer, I remember in that last 90° corner he just turned the steering wheel all to the right, and the car then slowly turned it hehe

[Guest]

oversteer and understeer is far too simple a word for what is going on.
Having a rear wheel propeled vehiclewith 900 horses on demand and 600something kilos to propel theres always more power than traction available,so powerdown oversteering is a fact of life especially at low speeds.But traction control helps a lot there and so you can bet todays cars in F1 feature a fair bit power oversteery setup and let the traction control care for the slip angles.
As you approach a corner ther´s necessaryly a tad of understeer in the car until the apex is reached,because if not you could not get into the gas early(the oversteering car is beyond its optimum slipangle at the rear first any power application result in more slip angle,no tyre is left for acceleration)
But true,it is also driver preference:You could throw the car into the corner open the exit with the oversteery car straighten it at the apex and accelerate straight out of the corner,very often a very quick way around a circuit (In that case you have to work very much with the car manipulate it constantly,whereas the understeerng car approaches it´s limits predictable and only slowing down recovers grip.the understeery dog is what Minardi has.The minardi boys hustle the car into the corner overdriving it wich leads to a snap oversteer ..that is purely driver induced.they just don´t have the bfrontend grip,they´d need,or cannot make the tyres survive if they setup the car correctly for the practise.

[Guest]

Well, before going too far. It is important to make borderline to our topics here. What I'll talk here is INDIVIDUALLY loosing front-grip or rear grip. Loosing front-gtrip means loosing control & loosing rear grip means unstable. Of course loosing control is more trouble than just unstable.

But, if we are talking about loosing both grips, it is important to know which grip to loose first. If front-grip first, you car is like a bowling-ball, just going straight without any control. And when you loose rear grip first, your car will spinn to a vertical axle and going out of the track (without control either).

Which one is more dangerous, well I would say that understeer is easier to control but it is not usefull for anything. And oversteer is more difficult to handle but sometiome driver (especially rally-driver) need it to save time when turning the car. However, both of them are dangerous if too much.

[Alic01]

I think the guest has hit the nail on the head here.

The real answer is that a perfect set up of car would provide the right balance of both under and oversteer. This would give a very predictable car which in turn leads purely to confidence.

I think it is that confidence that then goes on to let the driver make the difference, that is why Michael wins - hes has a fantastic level of confidence in his car and can push it to the limit.

All of the circuits are a juggling act and the teams job is to set up the car to provide the optimum compromise for the entire circuit.

[Guest]

i would never say a oversteering car is more dangerous than a understeering one.
The oversteering car you can steer actually with the Gas,understeer you have to get out of the gas completetly to regain control.As long as your car has no snap oversteer this is a very driveable controllable and very fun to drive setup .But it may compromise the maximum laptime for the conservative driver.
On the other hand with the understeering car you just turn in earlier than you would with a neutral car and work on it until you get the maximum corner radius possible with the max speed.

[tempest]

For Most of us who have a little bit of experience driving at or close to the limit (and who know where that limit is in our own cars) what you guys say is true, but consider my mum who never drives fast or my sister who has had her licence for 2 months and the circumstance is totally different.

Understeer for them is a predicable, normal thing, but when I made them learn how to correct an oversteer situation on a dirt road they scared me a lot!

Since it happens fairly quickly and is a fairly violent movement, most inexperienced or incompetant drivers will panic and overcorrect, which just causes the tail to flick out the other side of the car or jump on the brakes which can cause a 90-180 degree spin.

As for me, I prefer a slight oversteer in low grip situations cause it gives you a better look at the corner and you can balance the car on the throttle. For competent race drivers on a circuit I dont believe that either is safer than the other.

[marcush.]

tempest,you really summed it up perfectly,with the possible exception of the novice driver overcorrecting.
Any violent sideways movement of the rear will bring your heartrate up if you are not aware of what is going to happen.I´d call this snap (oversteer)If the cars setup is balanced towards a slight oversteer as soon as power is fed in there´s no surprise so even a complete novice is confident as the car gives feedback and responds on throttle application.It inspires confidence,as feeding in the throttle opens the corner exit you need less lsteering lock and the car is not hunting you.think about it.
Unfortunatelly most newbies tend to try braking late and try to turn in with the frontwheels on fire ,instead of sacryfying some entry speed for a good apex and exit to begin with. but that´s a completely different story...(But we saw it on TV the other weekend with someOlivier P. and J.P-Montoya if I remember correctly...)

[Silver-Arrowz]

For Joe Average, Oversteer is more dangerous.

When a car understeers, lift off throttle and front wheels gain traction again.

In an oversteer situation, lift off the throttle suddenly and the rear will snap. To gain traction again you have to lift off gradually.

The average driver will most likely lift off suddenly when they lose traction.

[dumrick]

People, allow me to make here an important distinction, in a thread that merges Alfa 147's and F1's, and that can be read by any newbie kid that may have the hurge to try the theory in mama's car:

It depends greatly if you are talking about FWD or RWD cars!!!

I know this forum has people from Australia and USA that can spend their lives without never driving a FWD car, but has a lot of Europeans also that drive daily that kind of vehicle.
And, yeah, I agree that, for the average driver, understeering is more safe, but mainly for the reason that many people's first reaction, when something gets out of the normal, is lifting the throttle or breaking!!!

[Monstrobolaxa]

I know this forum has people from Australia and USA that can spend their lives without never driving a FWD car, but has a lot of Europeans also that drive daily that kind of vehicle.

Humm...I'm in Canada at the moment on holidays/working in a friends shop called BMC Automatic Transmission Centre (in Edmonton) and I also had the impression that most of the cars were RWD but in fact almost all cars post 1990 are FWD (except the pick-up trucks)! Even the 1985 GM car my dad had here in Canada (untill it was sold in 1999) had FWD....

(of topic: take care of the drive shafts in your cars in this GM car my dad had the left drive shaft broke in the middle of the high way....it was quite frightening)