Wikipedia says that an anti-roll bar is a device that balances the weight of car between the wheels, preventing it from rolling. I want to simulate this in a game, but I don't know the equations behind it. I need to know how much weight the anti-roll bar transfers to each wheel. That means that I need to obtain a value that I can add to the load of wheel to manage it.

$W_{load} = W_{static} + W_{transfer} + W_{anti-roll}$

The static load is dependant on weight distribution. I do it like so:

$W_{static} = L_{0} / L * m * g / 2$

Where $L_0$ is the longitudinal distance from the opposite (e.g., if checking the rear wheel, than this is the front wheel's distance) wheel joint axle to the centre of gravity, $L$ is wheelbase and $m$ is mass of the car.

The $W_{transfer}$ is acceleration-dependent.

How can I obtain the $W_{anti-roll}$ value?

  • $\begingroup$ It might be a good idea for you to ask a question about how best to go about simulating the dynamics and handling of a car in general. I can sort of see where you are going with the questions you are asking but they do seem a bit disjointed and it might help you to get an overall understanding of the problem as whole if you can describe your objectives, resources and limitations. $\endgroup$ Mar 7, 2016 at 21:35
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    $\begingroup$ If I asked all at once, it resulted in requests of tons of equations and so would be 'too broad'. Imagine that you had to answer at once: -How to make down-force in game -How to make anti-roll bar system in game -How to make correct forwards traction force -How to do ___ $\endgroup$ Mar 8, 2016 at 5:51
  • $\begingroup$ I think that you need to find an unified approach to the sorts of approximations and overall approach to modeling that will give you the right balance of realism and manageability. For example a good question might be 'What are the key parameters for modelling the performance and handling of a racing car in a computer game?' and go on to describe the level of detail that you want and the sort of level of complexity that you are prepared to deal with. A more holistic approach might get you a reasonable dynamic model that you can tweak with coefficients. $\endgroup$ Mar 8, 2016 at 21:00
  • $\begingroup$ Yeah, but I want it to also feel real by player. I mean when adjusting values and tuning car the player must feel it being real, see some realistic values and behaviors. $\endgroup$ Mar 8, 2016 at 21:01
  • $\begingroup$ At the moment it seems like you are trying to work backwards from separate real world subsystems as a design team would build them but greatly simplified, but if you start from the perspective of what a driver would experience in terms of net performance you might arrive at a model which is more useful to you. $\endgroup$ Mar 8, 2016 at 21:04

2 Answers 2


The anti-roll bar partially constrains the two wheels of a given axle to move up and down together.

"Partially" is emphasized, because the coupling is deliberately less than 100% — the bar is allowed to twist to some degree, acting as a torsion spring, in order to still allow the wheels to cope individually with bumps, etc.

As you make the antiroll bar stiffer, you'll get less rolling in turns, but the overall ride will feel "harsh" on bumpy surfaces. It will be very stiff in a race car on a track, and much less stiff in the family sedan.

And BTW, the distance between axles has no relevance to how the antiroll bar works.

  • $\begingroup$ The 'BTW' - I know. The 'As you...' - I know. However, I need to know How to calculate changes in forces or wheel wieghts or anything else due to this. $\endgroup$ Mar 8, 2016 at 18:45

I found my answer here. So I basically need to get the difference between compression in the two opposite wheels and multiply this difference by the bar's stiffness to calculate changes of suspension force on each side. Pretty simple. It is even simpler to do in my setup than what's described in the link, since I actually add this value to the suspension force.


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