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Discussion Starter #1
Hi all,

Yes, I know some cars are better balanced than others. Some cars are designed to handle turns with almost little to no understeer. However, isn't understeer just a matter of hitting the corner just at (or under) the car's handling limitations?

I really don't want to jump down the rabbit hole, but, if a certain car is designed and set up to take a corner at a maximum of (say) 50 mph, wouldn't it start to push if the car entered the corner faster than 50? In the reverse, if a car plows into a corner while going 50 mph, wouldn't it get more neutral slowing down under 50 before you get there?

I mean every car has a limit. Go faster than the car can handle and the car will understeer? Right?

Using 50 mph as a hypothetical base line, anything that can handle that corner well would be average. Any car that can't might be considered a car that understeers? Any car that can exceed the 50 without pushing would be better balanced?

I know I over-simplified, but it seems like an explanation.

I'm certain a similar discussion can be had with oversteer, but being loose is a more complex subject.

Any comments?

Thanks
 

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Yes any car can understeer under the right circumstances. Understeer occurs when the front tires do not have enough grip and the front end "pushes" in the opposite direction that the wheels are turned. Vehicle speed is one factor, as you mentioned, but there are many other factors like road surface conditions, tire type/size/tread depth, weight transfer, engine placement, etc.
 

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Understeer is designed into virtually all cars upon factory set up. The idea is there to keep an average driver from uncontrollable oversteer. Experienced track drivers prefer a neutral balance as to modulate control at the point of breaking loose. If 2 ident cars are set up the same , the one with more grip will corner faster. Tires play the biggest part along with negative camber to keep the tire from rolling over and maintaining the largest possible contact patch.
 

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Poor braking technique is also a factor that can induce understeer particularly in light front end cars like Porsches.

If you brake too late and turn into the corner whilst still braking the front can lose grip and under-steer off the track or onto the other side of the road. I think maybe front engined cars with more weight over the front tires can get away with this a little bit with braking more possible during turn in.

With mid or rear engine cars it is more critical to get all the braking finished before turn in, particularly if you are carrying a lot of speed into a sharp corner and going down hill.
 

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2019 718 Cayman - Manual, PTV, PASM, Sport Chrono
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Yes. Any car can and will understeer. The question of balance, (and therefore handling) isn't just about what a car does when you ask more from your tires than they can deliver.

Balance is about how the car reacts to given driver inputs, and IMO particularly how a car responds to brake and throttle input at various points in a corner. A nicely balanced car will transition from understeer to mild understeer in a steady-state corner without any change to the steering wheel angle - simply by applying more (understeer) or less (oversteer) throttle.

Similarly, any rear wheel drive car with power will also transition to gross oversteer with too much throttle mid corner as well, if you ask for too much from the rear tires (lateral grip plus acceleration grip over what's available).

Handling is about the ability to use the throttle to adjust your line when entering, maintaining, and exiting a turn. Very good handling cars are often a challenge to drive well, because they respond so well to driver input that precise adjustment is required to maintain grip throughout a corner.

Many folks think "good handling" means "high lateral grip" which is wholly unrelated. A good handling car with only .5g of grip can be transitioned from understeer to oversteer or kept at the limit of traction all by the driver's control, the same way a good handling car with 1.2g of grip can. The limit is just different, and so too are the speeds at which that limit is reached.

< Insert discussion of Lotus Super 7 and Mazda Miata and BMW E30 and Honda s2000 and BRZ twins here... :) >
 

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2019 718 Cayman - Manual, PTV, PASM, Sport Chrono
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Poor braking technique is also a factor that can induce understeer particularly in light front end cars like Porsches.

If you brake too late and turn into the corner whilst still braking the front can lose grip and under-steer off the track or onto the other side of the road. I think maybe front engined cars with more weight over the front tires can get away with this a little bit with braking more possible during turn in.

With mid or rear engine cars it is more critical to get all the braking finished before turn in, particularly if you are carrying a lot of speed into a sharp corner and going down hill.
In my experience, turning and braking will result in understeer far more in a front engined car.

The dynamic is how much weight is transferred to the front tires. A given tire only has so much grip, based on contact patch, but that contact patch can only get so big. With lots of weight in the front, a FE car under heavy braking can be asking the front tires to slow well over half the weight of the car. If you then ask those tires to also turn that car, it's very easy to end up exceeding the grip they can deliver, and pushing off into the weeds.

A ME or RE car can (with appropriate springs and damping) instead transition less weight to the front tires at a similar g force, leaving more grip for turning/lateral control.

However, that also means more weight remains to be slowed by the rear tires, which therefore have less available grip for lateral control, and thus can break loose. The front has grip to spare, the rear has no grip to spare, and you spin backwards into those same weeds.

In practice, it's not so black and white, but the advantage of mid engine is that the tires share the load more evenly in more situations than either front or rear engine cars.
 

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I can agree with some comments but I respectfully must offer more perspectives. The best drivers are those who manage weight transfer in the corners, otherwise known as threshold braking. Adding weight to the front tires while turning will increase grip. Picture an F1 car that looses a front wing. Without the down force it creates the car will push . If the rear wing is incorrect, oversteer.

Threshold braking simulates the same affect by loading weight to the front tires for grip management. It’s the finesse of the brake pedal that pro drivers have mastered. The key here is all about modulation of brake force through the corner just before apex. To my point , this is what advance drivers are looking for when choosing a race pad. Race pad specs detail the grip at temperature and talk about ease of modulation based on vehicle weight

All of us on this forum who track our cars love our mid engine platform for what it offers in way of balance . To drive these cars at the limit is rewarding in a way few can appreciate. When you learn to master the the brakes, you will become part of the few. When my students become advanced drivers , I’ll ask them what they are working on in their session. The fast ones with real talent all say ‘’ BRAKES ’’
 

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2019 718 Cayman - Manual, PTV, PASM, Sport Chrono
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Adding weight to the front tires while turning will increase grip.
...until the available grip of the front tires is exceeded. :)
 

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Discussion Starter #10
Using a Cayman S as an example, the car should enter the corner and get to the apex fairly neutral up to the limit? Provided the car is set up properly. Of course.

Another example, even a front wheel drive Honda Civic won't push through a sweeper if driven well below it's limit. One might even feel it start to plow as it approaches its limit of adhesion? But it won't always exhibit be tight through a corner.

****, even a Suburban can ease through a wide corner at something like 10 mph.

All else being equal, there's a point where even a Cayman will understeer. How many cars (non race cars) made today are totally neutral up to its very limit before it snap oversteers? Unless I'm totally wrong, the vast majority of cars built today will start to push before it loses adhesion.

Again, if a Cayman can take a corner 20 mph (hypothetically) faster than said Honda, that doesn't mean it won't eventually understeer.

How off base am I?
 

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Any car will understeer. Take any vehicle and drive it onto an ice rink at high speed and turn the steering wheel. The instant the car turns less than the steering wheel is commanding you are understeering.
 

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Not sure what you're trying to get at here, @Baka1969 - but I enjoy the topic nonetheless.

My Cayman understeers literally every time I drive it, as I choose to use the throttle to push the front tires either to correct for too much steering lock at turn-in, or as I accelerate from apex to corner exit while slowly unwinding the wheel.

It's one of my favorite things about driving - using the throttle to place the car. I do it in my Cayman as often as I do it in my Pickup truck.
 

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I haven't seen this mentioned, but the old Barber School book "Going Faster" points out that if you apex too early at max speed for the corner, you are going off the track and turning the wheels more only results in understeer before you leave the track. Apexed correctly, it says, a neutral balanced car may feel like it is oversteering at the apex, when it isn't because its rear wheels are further out than the fronts. To @EuroKip's point about braking, there is always the famous Mario Andretti quote, "It is amazing how many drivers, even at the Formula One level, think that brakes are for slowing the car down."
 

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"Can any car understeer?" he asks. My first car, half a centur ago, was a BMW 700, a small 2-cylinder, rear-engine sedan. It oversteered heavily, dangerously, took some experience to corner smoothly. Making it understeer would have taken some serious intent. I'm not sure it was possible in any normal road condiitons.
 

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I can agree with some comments but I respectfully must offer more perspectives. The best drivers are those who manage weight transfer in the corners, otherwise known as threshold braking. Adding weight to the front tires while turning will increase grip. Picture an F1 car that looses a front wing. Without the down force it creates the car will push . If the rear wing is incorrect, oversteer.

Threshold braking simulates the same affect by loading weight to the front tires for grip management. It’s the finesse of the brake pedal that pro drivers have mastered. The key here is all about modulation of brake force through the corner just before apex. To my point , this is what advance drivers are looking for when choosing a race pad. Race pad specs detail the grip at temperature and talk about ease of modulation based on vehicle weight

All of us on this forum who track our cars love our mid engine platform for what it offers in way of balance . To drive these cars at the limit is rewarding in a way few can appreciate. When you learn to master the the brakes, you will become part of the few. When my students become advanced drivers , I’ll ask them what they are working on in their session. The fast ones with real talent all say ‘’ BRAKES ’’
I agree, braking is one of my main problems on the track. My terminal velocity is not too bad but then I find myself usually braking too long and not hard enough or at the wrong time. Are you able to describe what we should be aiming for the most optimal braking?
 

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Any car can understeer, and part of it can be attributed to driving style, but more than that, its how the car is setup with regards to suspension geometry such as center of gravity, weight distribution, ride height both front and rear, role centers, roll axis inclination, steering axis inclination, and adjustments like caster, camber, toe, sway bar setup, shocks, tires etc

A person who is experienced with chassis setup can make virtually any car handle excellent and tune it either understeer or oversteer at corner entry, mid corner or exit... Bars, shocks, springs, tires, wheels, all have an impact in different ways.

Keep in mind that car layout such as FWD, RWD, AWD, front engine, mid engine, rear engine etc... will all have tendencies to different handling dynamics and some are better than others.

There is a reason that the Cayman handles so well... Its a combination of the mid engine layout the design of the suspension and everything else.

I can tell you that with my new Ohlin shocks on the Cayman S, I can make the car, understeer, oversteer, or nearly dead neutral just with a few adjustments of the shocks, and that is a pretty simple shock adjustment... it gets way more complex with double triple and higher shocks which allow you to tune high speed, slow speed, digressive, linear shocks speeds and curves.

Many manufactures tune cars to understeer for liability reasons. Just changing a swaybar on one end only can make a huge difference... bigger isnt always better with this stuff as well.
 

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Set up is certainly key, and the Cayman is so well balanced partly due to the mid engine. I used to race an 80s Omni, which normally has massive understeer being FWD, front-engine with a factory weight bias of about 60/40. Through a combination of shocks, springs, sway bars, and tire pressures, I managed to get it pretty neutrally balanced (and dropped 2 secs a lap).

As for getting anything to understeer, as others have said, a big part is what you do going into the corner and what you do while IN the corner. At PECLA I was in a 911s. The instructor was talking about how the 911 is know to oversteer because of the rear mounted engine. If you enter a corner and are on the throttle then lift mid-corner -- oversteer galore. However, he had me brake as normal, turn in to a 90 degree right, then floor it mid-corner. He assured me we'd be fine....

The thing understeered like a dump truck.

The sudden weight shift to the rear, combined with the chassis dynamics (engine behind the rear axle), it essentially lifts the front wheels enough to make them useless. Very interesting lesson in car dynamics.
 
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