What's the point of staggered wheels?

[Norm Peterson]

I keep hearing this over and over again. And I'm sure all manufacturers believe it.

But why on Earth should understeer be any safer?

Because while you have direct control over the direction that the front wheels are pointed in, you do not have that "luxury" where the rear wheels are concerned.

Understeer is inherently self-limiting, where oversteer is self-energizing at least to some degree. I'm not talking about oversteer caused by a too-anxious throttle foot here, because a car in that scenario could well be inherently understeerish (heavily so, even) and you blew through rear tire grip via the vector sum of lateral plus longitudinal grip requirements.

I hate understeer. There's nothing worse than plowing straight on with the front wheels completely out of control.

Understeer by reason of over-driving. Driver error.

Recovering from oversteer is easy-peasy, just dial back the gas a little and turn the steering wheel towards where you want to go

I have my doubts that your car's understeer budget math would call that situation 'oversteer'. Closer to neutral steer, maybe.

If it was true oversteer that was threatening to get out of hand, you wouldn't dare to even breathe off the throttle, as even a little forward load transfer would plant the front tires even harder relative to the rear tires (which would be losing vertical tire load at the same time). Chances are you wouldn't dare to add throttle either (that pesky vector sum thing). If you've never been there, its neutral throttle/maintenance throttle + prayer time.


Norm

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[Norm Peterson]

I agree. But exactly the same will happen if you don't catch an understeer. The only difference is which way you'll be facing while going over the cliff. Understeer will allow you to see it coming.
And understeer is harder to catch.
Oversteer requires fast (but natural) reflexes.
Understeer requires fast and unnatural reflexes, plus a lot of space that you normally don't have.

So, to sum up:
- with oversteer you stand a fairly good chance of recovery
- with understeer the chances of recovery vary from slim to nil
- if you don't recover from either of them, you will go into oncoming traffic or over a cliff

See above post.

To me it still looks like oversteer is the lesser of two evils.

If it looks like that it's because understeer has been given an unrealistically bad image.

The truth is, this whole topic isn't some binary all-the-way-off/all-the-way-on, max-understeer/max-oversteer thing with nothing in between.

You need to think of this as a complete spectrum, where your car operates at various points along it. This where "understeer budget" enters the picture, and this is something that can be mathematically assessed.

There's too much detail involved to go into what parameters go into cornering compliances, but I think a decent 'Cliff's Notes' version reads something like this . . . in terms of understeer budget as degrees/g total front cornering compliance relative to total rear cornering compliance.

Neutral steer = 0°/g
Understeer = any positive value of °/g
Oversteer = any negative value of °/g . . . think "negative understeer" here

Obviously a car whose US budget is 10°/g would be horribly understeerish and totally frustrating to drive. And a car with an US budget of -8°/g (think 8°/g OS) would probably have you changing your shorts every time you took it much past 0.4 or 0.5 lat-g.

Light US is really your best friend under nearly all driving conditions. Maybe not for autocrossing a FWD car, but that's kind of outside the scope of US budget discussions for a Mustang. You don't have to take my word for this; Randy Pobst has written at least one whole column with the same point of view.


Norm

 

[Vlad Soare]

Understeer by reason of over-driving. Driver error.

Yes. That's the idea.
I'm not talking about how the car behaves when driven at the limit on a race track.
I'm talking about what happens if an average driver, on a public road, enters a corner a bit too fast for the available grip. A common mistake that a lot of people make.
If the car plows straight on no matter what you do, that's really bad.
If the front grips but the rear goes out of line, that's still bad, but to a lesser degree.
And yet manufacturers have gotten into their heads that the first situation is preferable. Beats me why. I'd take the second anytime if given a choice.

 

[Norm Peterson]

Yes. That's the idea.
I'm not talking about how the car behaves when driven at the limit on a race track.
I'm talking about what happens if an average driver, on a public road, enters a corner a bit too fast for the available grip.

Seems obvious that you've never entered a corner a bit too hot in a car that truly was oversteerish. As in oversteerish on lift throttle or braking and oversteerish under leading throttle. Nowhere to go with the pedals that wasn't going to get the tail loose.

I have, and it was on the street (Interstate exit ramps, actually), and no it wasn't fun AT ALL. Let's just say a particular combination of tuning efforts completely hosed the balance of front vs rear tire stiffnesses and leave it at that.


Norm

 

[Shadow277]

I keep hearing this over and over again. And I'm sure all manufacturers believe it.

But why on Earth should understeer be any safer? I hate understeer. There's nothing worse than plowing straight on with the front wheels completely out of control. Recovering from oversteer is easy-peasy, just dial back the gas a little and turn the steering wheel towards where you want to go, whereas recovering from understeer requires not only a maneuver that is completely against all of your instincts, but also a lot of space - more than the width of a lane. Most, if not all, of the untrained drivers, when faced with understeer, will turn the steering wheel even harder while stomping hard on the brakes. Perfect recipe for falling off the road in a left-hander, or going straight into oncoming traffic in a right-hander. And even if you do know the proper procedure and manage to fight your instincts, you will run out of road before being able to fully recover. One lane isn't wide enough to allow you to unwind the steering little by little until you gain traction, then to make a new attempt at steering round the corner. By the time you do that you're already in the ditch.
Understeer sucks.

So, what am I missing? What's so "safe" about it?

So no oversteer ever for me?

 

[raptor17GT]

i assume Vlad hasn't driven an MR2 turbo on the street either. More bite than an angry bear

 

[Norm Peterson]

So no oversteer ever for me?

In the end, it's going to be your call. But I'd pay attention to RP here . . . especially if anybody else is going to be driving your car. Boldface mine.

• May 31, 2016 at 8:03 PM

This article first appeared in the April, 2016 edition of SportsCar Magazine. SCCA members can read the current and past editions of SportCar digitally here after logging into their account; To become an SCCA member and get SportsCar mailed to your home address monthly in addition to the digital editions, click here.

I hate to bring this up, but think about your last crash. Could you see it? Yes, I’m serious. If you could, you were most likely understeering. When you’re backwards, you don’t get to see the impact. That would be oversteer.

Understeer is your friend, because it’s far easier to control. It’s like Dad – a gentle guiding hand, who won’t spank you unless you really deserve it, and hopefully teach you a lesson. Understeer is when the front tires are sliding more than the rear. Racers often refer to it as a push. Especially down here in the South. Sorry if I’m talking down to you, dear readers, but let’s define for those with Xs on the rear of their racecars (the “Rookie Warning Mark of Danger”).

Historically, manufacturers deliberately tune their cars to understeer. Why? Because it creates stability. Stability saves on legal bills later. George and Martha stay on the road when swerving violently around the errant toddler on his big wheel, since they probably have never driven in Solo, and don’t know how to handle simple offset gates. But, for us in the racing world, what is the benefit of that? After all, we drive flat-out, do we not? Out on the ragged edge.
Confidence, that’s the payoff. It is invaluable to the driver. The outstanding benefit of understeer. Confidence comes from knowing what to expect. From being able to control what’s next. A little understeer keeps the tail in line when going deep, deep, deep into the brake zone to take the lead. A little understeer makes it much easier to keep the car on the absolute limit of traction and fill the friction circle as you blend straight hard braking into 1.5g cornering.
Think about it. Where is the weight when you are braking? All forward. How’s the rear? Light. Very light. Does this sound stable to you? It’s not. If your car is a little tail happy, this will only get worse. A little understeer gives the driver something to lean on – a safe landing zone for the dive bomb.

It’s the middle of the corner where understeer can be a frustration. Understeer demands patience. An impetuous early application of power moves that braking weight back to the rear. The front gets light and loses grip. Part-throttle exaggerates any tendency to understeer. Early throttle is why many amateur track cars I drive end up with too much oversteer. See what I mean here? Regular Joe often finishes braking early, and next, naturally, goes to the power early, taking load off the front early, creating understeer. So, Regular Joe stiffens the rear swaybar to eliminate that mid-corner understeer. If a chassis is set up to be perfectly balanced with early acceleration – a very common mistake – it will likely be too loose everywhere else. I’ll tell you, I’ve rocked several people’s worlds by just stiffening the front swaybar. Always consider: is the handling trait you hate, the car or is it you?
Exiting a turn flat-out, in a rear or good four-wheel drive, should evidence very little understeer. All the power is twisting the back tires, adding slip angle. Driving off a corner in a sweet, small power drift is one of the most rewarding moments in motorsports, made possible by a stable platform with a one to two understeer, on a scale of 10.

So, understeer is a good thing for the vast majority of drivers, on and off track. But some drivers are so good at counter steering that this is not a factor. I blame karting. Karts are fastest driven in a constant state of oversteer. Or just the drifting gene. If you must share a car with one of these aliens, get your skid pad training in first.
An ideal setup will have enough understeer for the confidence-inspiring stability that every driver needs to go really fast. Having a car under you, the Indy racers used to say. Too much understeer will make you feel frustrated. Sense your mood, it tells you how your car is handling. When you find yourself waiting on the front end, waiting for the car to point at the apex, waiting to floor the gas pedal, pushing wide, pushing wide, missing your apex, it’s frustrating.
So, how do you compensate for that push? Pull those levers to adjust your swaybars, stiffer front, softer rear. There have been Porsches I’ve driven where I start full one way – soft front, hard rear – then by the end of the stint, the bars are fully the opposite – hard front, soft rear – as fuel load lightens nose and rear tire wear. That’s life in older 911s.

But most racers do not have this luxury – it’s even illegal in many series – and it’s pointless pitting to change your bars in an SCCA Club race. So, compensate with your driving. Turn a little earlier. You have to, because you know the car does not turn well, so it takes more time. And trail brake. Understeer equals trail brake. The front tires are begging for more load. Brake very lightly as you turn in, for a long time, until you know you will make the apex. This is a great speed secret.
Further, be patient on the throttle, because what does it do to your weight? Sends it rearward. Wait, wait, wait on power in an understeering car. Turn early, but apex late, so you can straighten the wheel when you finally add power, and take advantage of a benefit of understeer; power down traction. Exit speed is king, not apex speed.
Plan B? Gas it early and drive with the throttle, North Georgia Redneck style (by the way, four-time Pirelli World Challenge GT Champ Johnny O’Connell and I live only a mile apart outside Atlanta). Power oversteer is loads of fun, and I truly wish it was the fastest way. It is the hot tip on dirt: let’s SCCA RallyCross! But it’s really hard on rear tires on pavement. Too bad. A little bit is fine, but a lot will ruin your on-track life.
Understeer. Maybe not the most entertaining, but if you want to win, recognize that a little of it is your friend, and get by with a little help from your friend.

Words by Randy Pobst

Norm

 

[Vlad Soare]

I have, and it was on the street (Interstate exit ramps, actually), and no it wasn't fun AT ALL.

I'm sure it wasn't. But I'd wager that simply plowing straight on without any control whatsoever would have been even less fun.
Very interesting article, but it seems to deal with these things from the perspective of a racing driver, whereas I'm more interested in that of an average Joe. The way he describes the recovery from an understeer (let alone using it to your advantage) is way beyond what an average Sunday driver is capable of.

 

[WD Pro]

Ignoring what drivers want and what may be fast etc, I think the understeer / oversteer thing and how OE's set their cars up from the factory has a lot to do with public perception :

• Understeer / plough straight on off the road. Public perception = you were driving to fast / riving like a dick. Very hard to explain this one away to your mates in the pub.
• Oversteer / exit the road backwards. Public perception = those cars are dangerous / widow makers. Much easier to explain away in the pub and blame the 'dangerous' handling.

In my opinion that's why a 'mainstream' car manufacturer will fall on the side of caution and dial in a bit of understeer, 'in general' it helps to protect the cars reputation and maybe it also helps to keep the general public just a little safer and more confident in their vehicle.

WD

 

[Mazman]

I have on my MX5 with added CUP2s and coilovers(relative stiff springs) induced a bit of unpredictable oversteer on track use.

I will be adding a quite big diameter front sway bar to balance out the oversteer to try to have a more predictable behavior. This will of course require some more experimenting however the unpredictable oversteer is not fun and it has showed it's face on the streets as well

 

[Vlad Soare]

Ignoring what drivers want and what may be fast etc, I think the understeer / oversteer thing and how OE's set their cars up from the factory has a lot to do with public perception :

• Understeer / plough straight on off the road. Public perception = you were driving to fast / riving like a dick. Very hard to explain this one away to your mates in the pub.
• Oversteer / exit the road backwards. Public perception = those cars are dangerous / widow makers. Much easier to explain away in the pub and blame the 'dangerous' handling.

In my opinion that's why a 'mainstream' car manufacturer will fall on the side of caution and dial in a bit of understeer, 'in general' it helps to protect the cars reputation and maybe it also helps to keep the general public just a little safer and more confident in their vehicle.

WD

I think you may be on to something here. This is quite plausible.

 

[Norm Peterson]

I'm sure it wasn't. But I'd wager that simply plowing straight on without any control whatsoever would have been even less fun.

Disagree. True oversteer threatens to be a much more abrupt loss of full control. Understeer gets you there much more progressively.

Very interesting article, but it seems to deal with these things from the perspective of a racing driver, whereas I'm more interested in that of an average Joe. The way he describes the recovery from an understeer (let alone using it to your advantage) is way beyond what an average Sunday driver is capable of.

This re-quoted part is still true even in street driving. Lightly re-stated/re-emphasized . . .

Confidence, that’s the payoff. It is invaluable to the driver. The outstanding benefit of understeer. Confidence comes from knowing what to expect. From being able to control what’s next. A little understeer keeps the tail in line when going deep, deep, deep into the brake zone to take the lead. A little understeer makes it much easier to stay within the limits of what the driver's skill set can realistically cope with.

Norm

 

[Vlad Soare]

Then how about a car that had a tendency to understeer when left to its own devices, but whose understeer could easily be turned into a controlled power oversteer? Would that be the ideal case?
That certainly looks like the best of both worlds to me. And the Mustang, as far as I can tell, does seem to be just like that.

 

[Norm Peterson]

Then how about a car that had a tendency to understeer when left to its own devices, but whose understeer could easily be turned into a controlled power oversteer? Would that be the ideal case?

As long as the driver does his part, anyway. But that's kind of implied by "light understeer", where the car is close enough to 'neutral' that adding some amount of acceleration force to the rear wheels effectively increases their slip angle(s). Keep in mind that this is not a condition that the car would inherently seek without the driver maintaining continuous control to keep it there.


Norm

 

[luc]

Cars are designed to the lowest denominator driver
What is the normal and first reaction of a driver when the car start to understeer/push going through a corner?
Lifting of the gas... what happen then? Weight is transferred to the front, front tires get more traction and car turn... very simple and don’t require any driver training
Oversteer control requires finesse, training and balance..
seriously, which one is safer for the average driver?
Not even close

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