How do you solve your car’s handling balance problems when everything you’re trying doesn’t seem to work? Here is a 5 point checklist you can use to structure your approach and start solving your handling balance issues. Tick each one off in order and move to the next…
Why Fast Drivers Care About Handling Balance
As a racer – or track driver – all you want is a fast, well balanced car, with good grip and consistency. But what if your car’s handling is not well balanced, or worse, feels like it is try to kill you!?
You want a car that enables you to extract the most performance with the least mental (and physical!) effort. You don’t want a car that, whilst fast, takes crazy amounts of concentration and energy to drive.
You might be the best driver on the planet, but if the suspension setup is not good, you’ll be at a best working much harder than you need too. At worst you’ll be slow, inconsistent and may even crash… a lot.
Suspension setup is not a new problem. But how do you start to find the best suspension setup for your track or racecar?
“Suspension is simple, isn’t it?”
On the surface a suspension is simple. In a basic racing car all it involves is selecting a set of springs, anti-roll bars and dampers, then pumping up your tyres.
I’ve covered tyres with my track tyre tuning guide… but what about the rest of it?
Well, in true Dunning Kruger style, suspension setup gets complicated… quickly.
This is because different parts of the suspension all contribute to the same handling balance experiences, but in overlapping ways. This impacts how your car is controlled and what you as a driver feel.
To tackle this, lots of very clever people have developed several theoretical concepts and models – with a lot of Maths!!
It is a lot to get your head around that many (many) people prefer to leave well alone.
For example, here is a shot of a spreadsheet I have been using recently to help a race team define their racecars ideal springs and damper curves:
It looks complicated to me and I made it !! … oh and this is the simple version!!
“Just drive it buddy…”
Of course you don’t have to know about or apply any of this suspension maths stuff.
Many racers simply treat their racing car like a black box.
Through experience, paddock wisdom (*cough* copying) and a good deal of trial & error, people do find a suspension setup they can get on with.
But is your suspension setup really the best it could be? And, critically how do you change it – and by how much – should conditions, problems or your driver preferences change?
In my humble opinion, having a better-than-a-guess answer to the questions of “what” and “how much” to change, are the key to success with suspension setup. It is where the “black art” approaches fall short and where most people get confused.
Great suspension setup is the key (clearly) but short of diving into some fairly heavy concepts (a-la that spreadsheet), I thought instead I’d share a kind of mental framework.
What follows is a way to help you logically work through an order of the challenges affecting your car’s handling balance.
Finding Your Suspension Handling Balance with The Ladder of Laptime
The key concept to remember with suspension and handling balance is that nothing acts in isolation. Luckily, whilst different things compete, not everything contributes in the same way or the same amount.
The idea here is if you know the order in which things contribute – more or less – then you know where to focus your efforts before moving on to the next thing.
Think of the following items as building one on top of another. If the previous step is not “right” then focus here before looking at the next step.
You are still going to have to determine what “right” means for you. The aim of this hierarchy is to help you structure the order in which you start looking.
Aerodynamics… Absolutely amazing when they work for you. Total disaster when they don’t (seen these porpoising F1 cars?) If you have aerodynamics on your car then add understanding centre of pressure verses speed as step 1.5 – but I’m kind of assuming you know what you’re doing.
Tyres (or tires!) dominate everything. The good news is that the more you can understand your tyres – did I mention my tyre tuning guide? ? – then the easier will be to get answers to caveat 1. Your tyres dominate everything to do with handling and grip.
The 5 Rungs of Samir’s Ladder of Laptime
There are five primary areas I look at when trying to tune the handling balance of a car. I finding they are best tackled in this order:
1- Mass distribution (and corner weights)
Where the weight is placed in a racing car defines the fundamental handling characteristics of any car. This is often defined for you by your cars design i.e. front engine or rear engine. Where there is flexibility it is best to put the mass low. This limits load transfer and that gives you more grip. You then want look to at your “corner weights.” This is the weight on each wheel.
If you run on tracks with left and right turns you typically want to have even weights left and right. If you have a car that will struggle to be even e.g. because your driver is off to one side, then tune your cross weights. Cross weights is where you add up the diagonal weights and compare them as a ratio. People have different approaches here but, if it helps you, I personally aim for 50% cross weight to start. If you have a car that has different handling left and right, start by checking your cross weights.
Things to know: Your mass distribution and corner weights.
2- Suspension Geometry (and alignment)
The suspension geometry is to do with how the wheel is aligned to the road. In practise this includes things like static toe, camber, caster and bump steer. It also includes other geometric considerations like roll centre height, camber compensation, caster trail, Ackerman, kingpin inclination and other suspension concepts. See what I mean about an overload of theoretical concepts!
Typically (luckily?!) the second lot you can’t normally do much about so it is just the static geometry that you have to play with.
What makes good geometry gets involved, but I try to remember that:
a) Your tyre will generate more grip when more of it is in contact with the road. This means when the car rolls into the corner, you want the tyre to remain upright. To do this I aim for a slightly titled in (cambered) wheel at the top because many suspension loose camber with roll i.e. MacPherson struts.
b) Your car will be slowed down whenever there is any toe angle. Again personally I tend to aim for parallel or slight toe out to start with. Adjusting toe a small amount will have a big effect on how the driver perceives the balance of the car. Changing toe will make the car feel more or less agile and responsive, especially on turn in. If balance in this phase of the corner is what you’re trying to tackle then I’d look at toe.
Things to know: Your static toe and camber settings
3- Displacement (Springs)
This how the vertical displacement of the wheel, relative to the chassis, is controlled i.e. going over bumps. In a basic racing car, this is controlled by a set of four “ride” springs and possibly one or two anti-roll bars. In more a more complex racing car they might have also have “third springs”, bump stops, second springs or even front to rear interlinked systems. These complexities only aim to overcome the compromises a more classical setup has.
At all times you are looking to control the balance of forces applied to the road as the racing car drives over bumps, brakes or goes round corners.
This is an area I see people often get confused. I can’t give you your ideal spring rates without specific information on your car. Instead I find it useful to consider these two things:
a) That tyres don’t like surprises The last thing you want to do is run out of travel or cause some other shock in the system. Shocking the tyre will only cause it to loose grip – normally when you need it most!
b) When talking handling, I think of the springs and anti roll bars as balancing mid-corner handling. Think what kind of car do you want at the mid corner when, in theory, you are at maximum lock and neither accelerating or decelerating. If you’ve a balance problem at this phase of the corner then I’d be looking at your spring and anti roll bar stiffnesses.
Things to know: Your spring and anti roll bar stiffnesses
4- Velocity (Dampers / shocks)
This is about how the speed of the wheel displacement above is controlled.
If the vertical speed wasn’t controlled then when a racing car went over a bump it would continue to bounce up and down forever.
A shock absorber or damper is used on a racing car to manage this. If you have no adjustability in your dampers that is fine. If you do then again this is an area I see racers struggle.
What I find useful to remember is that the damper is only doing something whilst the suspension is moving. Otherwise, in theory, the damper is not doing anything. The other thing, which took me ages to work out until I worked at a damper company!, is that the aim of a damper is to keep the tyre on the track. Going back to the geometry, the more tyre that is in contact with the tarmac the better. People often mean this when they refer to “minimising the contact patch load variation.”
Things to know: Dampers only contribute when the suspension is moving. Your “force velocity” curve (if you’re keen)
5- Acceleration (Inerters…)
Controlling not only the displacement and velocity, but also the acceleration of the wheel moving relative to the chassis is actually a fairly new idea in suspension systems. It is that new that most racing cars will actually have no way to tune this. I thought it worth mentioning for completeness here because it is interesting and relevant. It might also get you thinking about how you might incorporate something to do that. They have been doing this in sky scrappers for a long time with what is called a tuned-mass-damper. Renault F1 were famously banned from using them but teams developed an alternative known as an inerter (also now banned in F1.) By controlling the acceleration, you can cancel out movements and load variations before they occur.
Things to know: That 99.9% of people don’t need to worry about an inerter.
Tuning Your Handling Balance Is About Getting These Basics Right.
I find it useful to think through each step of this framework in order. If you can satisfy yourself that you understand and are on top of a section then move on to the next one.
In my experience, each stage has diminishing returns in terms of lap time.
Often I see people rushing to adjust damper settings. If you are only looking at damper settings but your geometry or corner weights are off, then you will never solve your handling issues.
When someone suggests getting the basics right, perhaps consider working through my Ladder of Laptime as a starting point.