“Will stiffer springs and shocks improve my car handling? It seems to me that if my car doesn’t lean as much in corners then I should be able to go around corners faster. Am I right?”
I hate being a professional suspension engineer, sometimes! The answer to both these questions is maybe – and that is really no help to you or this reader!
Someone recently asked me this same question and, well, it took me down a very deep rabbit hole – one that I’m not quite sure I found the bottom of yet.
What I can help you with is thinking through the puzzle. This will help you understand what is going on, decide what good looks like and give you a clear direction.
This short article is the perspective I gave when ask by SSW. Your feedback is welcome!
Addressing Car Handling Folklore
There is certainly some intuitive sense to the idea of stiffening up the car so it doesn’t lean as much in corners.
What you want is great car handling that just grips, turns and goes, right?
Well I can’t tell you if stiffer springs and shocks (or dampers) will achieve that in this specific case.
It might. It might not.
In fairness it is not clear from where this reader is starting from. The assumption is that this is a stock street car they want to improve the handling for on the track.
What should help you is to think through the question like this…
Describe Your Current Car Handling Characteristics
Start by defining “better car handling.”
Don’t over complicate this.
Ask yourself, are you currently fighting the car to get it to do what you want? Or, is it following your every command almost through telepathy?
If you are fighting your car ask yourself is it slow and lazy when you turn? Or when you turn the steering wheel does it cause a reaction so scary fast you’d feel safer prodding an alligator?
If it is slow and lazy, then yes, increasing spring stiffness might help you.
However…
Cornering Faster Is About Grip
Grip is all about your tyres (tires!) – as these are the only things that touch the road. Learn more about tyres here.
Yes, up to a point, the harder you press your tyres into the ground the more grip you get.
Your springs and dampers also influence the load each tyre sees, so this reader is looking at the right things. But is the assumption right?
During a corner, your spring stiffnesses influence how hard the outside tyre is pressed into the ground.
This certainly adds grip to that outside tyre.
Unfortunately, these springs also influence how much load comes off the inside tyre….
Ask What Is Happening To The INSIDE Tyre…?
Load coming off the inside tyre means less grip for the inside tyre.
It’s a pain that this happens because, as you corner faster, the inside tyre loses more grip than the outside tyre gains grip.
When you are looking at performance tuning of your suspension for limit handling, this becomes significant.
So when you’re thinking through suspension stiffness changes, don’t only think of the outside tyre gaining grip, think of the inside tyre losing grip too.
Softer springs will reduce the amount of load that comes off the inside tyre in a corner. This gives you potentially more grip overall for that axle.
That is why you might hear people say they want softer springs for more grip…
Sorry if these things seem to contradict each other!
How To Balance Your Car Handling Compromises
Suspension setup is all about compromises. It makes it fun (or frustrating!)
One tip you might find useful is to consider things at their extremes.
This can simplify lots of complexity. Take a listen to this podcast show for more detail on applying this idea.
In this car handling example imagine what would happen with incredibly stiff springs.
Then imagine what would happen with incredibly soft springs.
Sometimes when you do this thought experiment it gives you clear direction – like “Is centre of mass best high or low?” (Low.)
Other times, like in this case, neither extreme is what you want.
Find Other Metrics To Guide Your Decision
To help you decide how stiff your springs need to be you need another metric(s).
This makes you car handling question a multi-dimensional puzzle – like most things on a race car sadly. haha!
Driver happiness is actually one of those extra metrics you can use. In engineering terms you can characterise that as response and understeer balance.
Other metrics are tyre grip (ie peak vehicle accelerations) and body control (ie deg roll per g and aero contributions to grip.)
With those extra dimensions you can start to get a pretty solid answer to “how stiff should my springs be for better car handling?”
Finally The Driver Coaching Perspective For Better Car Handling
One driver coaching thing I might come back to you with before you seek to change the car.
Ask yourself are you, in fact, getting everything out of your current car setup?
The honest answer to this is always no. The data will tell you even if you don’t believe it yourself.
Consider this.
What would your favourite driver do in your car with that car handling balance?
Perhaps adapting to a different driving style would be faster? Or make the car feel like it had better handling.
What can you do in your driving to work more with what you have?
Maybe nothing can be done but if there is an opportunity in your driving then it could save you the hassle, and money of investing in, new suspension and shocks?
Take a moment to think that through.
We can be guilty sometimes of looking at changing the car and sometimes forget about developing ourselves as driver – I’m as guilty as anyone on this btw!
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