Race driving is a confidence game. As you get more experienced in racing, you get to be highly confident in your ability to control the race car, racing consistently up to the capability of you vehicle and your level of skill.
This might easily give you the impression that your racing skill could help you with setup - help you work out what is happening and how you could improve the set-up of your car.
Could not the highly skilled and experienced racing driver say what's needed to make the race car faster?
But our experience with grassroots racing clients is that this is not the case. For example, it is not possible for the driver to say in isolation, just by driving the car, whether the springs should be stiffer or softer. (Spring/Suspension stiffness is perhaps the single biggest contributor to improving the grip and performance of a non-aero race car.)
Racing drivers respond to the race car as they feel it in the moment. How else can we explain the fact that in...
Most racers realize their choice of suspension stiffness, the spring rates they choose ie (say in lbs/in, Kgs/mm, or N/m) are important.
In fact, for low or non-aero race cars, at Racing Car Technology, we have found choice of the suspension stiffness is the most important setting on the car for improving grip at the tyres and optimizing performance.
When buying suspension springs, how do you know what spring rates to order?
Parts suppliers, shock absorber and suspension specialists, and car preparation shops are likely to make a the choice for you, unless you say what you want.
Yet, even with very experienced people making the decision, most racing car spring selection is little more than informed guess work. It doesn't need to be that way.
In racing, it's the stiffness of the spring that counts.
What we’re showing you in the video is a unique way of measuring suspension stiffness. We’ve called this simple test the Racing Car Technology Bounce...
The static weight distribution front vs rear locates the centre of gravity in plan view (as seen from above). The position of the centre of gravity is very important in determining the balance of the car, as we shall see in this article.
For a new race car, an important early decision in the design process is the choice of front to rear weight distribution.
Equally, if we are racing an existing car, it’s important to know what our weight distribution is, so we can make decisions about the suspension set-up of the car.
How do we measure weight distribution?
If we have the corner weights, we can determine the weight at the front and rear axles as a proportion of the total weight. E.g. We may have 53% of the total weight at the front axle, leaving 47% of the total weight at the rear axle.
To get answers to these questions, let’s look at the problem from...
The details of anti-roll bar operation are discussed in our blog article, “Anti-Roll Bars. A Good or a Bad Thing?”
As indicated in that article, there’s much more to anti-roll bars than simply reducing body roll.
In this blog I want to focus on two super important characteristics of anti-roll bars in suspension set-up for racing…Suspension Stiffness in Roll and How You Get More Grip With Stiffer Springs and ARBs.
Suspension Stiffness in Roll
The anti-roll bar adds to suspension stiffness in roll i.e. In cornering, both the spring and the anti-roll bar contribute to the suspension stiffness as seen at the tyre contact patch.
I’m going to quote a vehicle dynamics expert here, so you don’t think I am making this up:
“Typically, a bigger bar on the front improves the perception of nimbleness, (agility), as it makes the outer tire work harder in the first half a second or so (of initial turn-in).” Greg Locock – Engineering...
When you turn the race car into the corner, the forward momentum of the car generates a lateral force at the front tyres, forcing the generation of what we know as "tyre slip angles".
Tyre slip angles are a property of the pneumatic tyre that allows the creation of substantial lateral force at the tyres, and in so doing, allows the car to turn.
If you just presented the steered road wheels to the road road rushing by without slip angles, it's a bit like presenting the wing on an aircraft without an angle of attack. For the aircraft, no lift. For the race car, no lateral grip. (If we had steel treads, for example, there would be no slip angles, and insufficient friction available to create any significant cornering force on an asphalt road surface .)
Why should you, as a racing driver, be interested in tyres slip angle?
It’s no good making random adjustments to your race car set-up at the race track. You'll most likely get lost with the changes you make, and end up not making the car any faster.
Magazine articles, "cheat sheets", and generalized advice you get on set-up from internet web sites, are particularly unhelpful. No wonder the general impression most racers get is that handling, as it applies to set-up, must be very complicated.
Even someone highly experienced both as a driver and a set-up engineer cannot tell what you need straight off. They can't just jump in your race car, do some laps, and then say you need XYZ springs and anti-roll bars.
What you need is a baseline set-up. The set-up we know is close to optimum. Then in testing, you and/or your team, can decide what changes you’ll try.
At Racing Car Technology, the baseline is the set-up we can do in advance in the workshop, then go to the track knowing we are in the set-up...
Here's the full version of TRE's video of this tarmac rally car on their 7 Post shaker rig:
TRE Dynamics are technical partners with Ohlins DTC, Germany.
You can see in the video, the shaker rig forcing vibrations in the suspension. About half way through, they show you a "track replay". The actual suspension movements from the track are reproduced.
Best dynamic grip comes from minimizing the tyre load variation, minimizing disturbance, minimizing vibration at the tyre contact patch. (Note the difference in shaker rig testing for road cars. The required set-up will be a compromise between ride quality - least disturbance for the driver and passengers - and best grip - least disturbance at the tyre contact patch.)
To minimize disturbance at the tyre contact patch, you need the required "natural suspension frequency" or "suspension frequency", as we regularly call it.
The "natural suspension frequency" is the vibration of the suspension...
Weight Transfer Part 3: How Does the Driver Control the Race Car?
This is the final part in our “Weight Transfer” series. See Part 1 and 2 home page /blog
Summarizing what we discussed in Parts 1 & 2:
Nowadays, “weight transfer” thinking is commonly used to describe what the racing driver is doing. The driver is said to manage or control the weight transfer. The “rate of weight transfer” is considered important. And as discussed in Weight Transfer Part 2, the driving coach Rob Wilson talks weight transfer almost exclusively when he describes what he is teaching to drivers.
Talking “weight transfer” with respect to race driving is a fairly recent phenomenon. Most of the authors of books on handling don’t talk about weight transfer in the context of the driver controlling the car.
My major sticking point with weight transfer thinking is that drivers cannot feel...
What do these three F1 racing drivers have in common? Kimi Räikkönen, Valtteri Bottas and a young Nico Rosberg (when he drove for Williams in 2006).
They’ve all been coached by Rob Wilson – “the F1 drivers coach”. He’s also coached many other professional drivers, racing in just about every pro racing series around the world.
Rob knows weight transfer. Most times, when he is talking about driving, he’s talking about weight transfer. He says that “the rate at which you transfer weight”, is just about the most important thing you do in a race car.
For a quick look at what he does, check out this video with Formula E driver, Karen Chandok. It shows Rob's great sense of humor as well:
2017 Belgium - Rob Wilson Driving School
Rob is teaching smooth introduction of the steering brake and throttle so as to maintain maximum grip. From that...
Racing drivers often talk about weight transfer – weight transferring forward under brakes, rearward under acceleration and from inside wheels to outside wheels when cornering.
Weight transfer concepts are hugely important in suspension set-up. Weight transfer across the car in cornering, is the basis of the most important tool we have in suspension set-up – using weight transfer distribution between the front and rear axles to adjust the balance of the car. But the driver is unaware of the weight transfer distribution itself - only the feel of the car resulting from the balance adjustment.
Weight transfer is the result of acceleration, braking or cornering. If you accelerate, brake or corner harder, you transfer more weight.
For weight transfer to be useful to the driver in controlling the car, the driver would need to feel the weight transfer, or something related to it.
Weight transfer in pitch and roll is just weight transfer coming off...