Hi everyone !

I don't know if its me or the game, but I noticed a weird thing when tuning the antiroll bars value.
Indeed, antiroll or sway bars are meant to reduce the body roll, and this has several effects.

For instance, a hard sway bar in the front means less lateral mass transfer in the front, so it reduces understeering, and even sometimes create oversteering.
For the rear, it's the opposite, hard sway bar means less oversteering, and sometimes understeering.

Now when looking at LFS, it seems that this theory is inversed (with all cars). For example, take the XRG, and put the sway bars value to 90 in front and 40 in rear. Usually, it would make the car oversteer bad. But in LFS, the car almost goes straight on... And the same "inversed" effect applies when rear is more than front (oversteer).

So I wanted to know if there was really a problem, or if it's just a misinterpretation from me?

Thanks a lot

A stiffer front bar, increase roll resistance, which INCREASES load transfer and causes UNDERSTEER due to tyre load sensitivity. A softer front bar decreases roll resistance and causes OVERSTEER (or at least tends towards that).

This is why you want to run the softest bars you can get away with within constraints of camber control, response, roll angle (which isn't important if you have good camber control) and balance

LFS is spot on here (it's really basic stuff so it'd be rubbish not to), and it is you that is wrong.

Sorry.

Edit: Why the french don't make sports cars?

Quote from evilgenius :

Thanks for the contribution!

Quote from Zen321 :

So I wanted to know if there was really a problem, or if it's just a misinterpretation from me?

I guess what you're getting at is that less roll means the CoG stays more in the centre, giving you better grip due to the load sensitivity of the tyres (load more evenly distributed between left and right side).

However, what you have to keep in mind is the ratio between front and rear antiroll. If you have a stiff front and a soft rear, the rear will lean in more while the front can't, causing the front outer wheel to be loaded more and the inner wheel less (less grip overall), up to the point where the inner wheel might lift off from the ground completely.

Okay I see now

I thought it was the mass transfer and not the load on the suspension that made understeering or oversteering under roll

Thanks for having made it clearer.

Edit : And btw, we made sportscar (Alpine, R5 GT Turbo and Loeb's Citroen for rallyes ), but we don't engineer them anymore (even if the Bugatti Veyron is crafted in France )

Hmm, good explanation

The anti-roll bars have no effect on load (mass) transfer (other than the pretty negligable effect of keeping the CoG height the same.

Load transfer is a product of CoG height, wheelbase or track, and lateral acceleration. Not springs, ARBs, camber, anti-squat or what have you.

But why exactly does a stiff rollbar increase load transfer, meaning more load is transferred from one side to the other?

I know that the load transfer is basically a torque as the car's CoG is above the wheels, meaning the wheels create force in one direction due to the road contact, while the mass of the car wants to continue travelling in a different direction. But what effect do the rollbars have there? All I can imagine is the "arm" created from the road surface up to the CoG being more or less stiff, depending on the ARB, but I don't understand why that affects load transfer.

Sorry, I should say that they have no effect on the TOTAL load transfer, which is only a product of...

ARBs control the proportion of the total lateral load transfer at the front and rear ends. A stiffer front will cause proportionally more to take place at the front, increasing the load difference on the front axle (which reduces grip due to TLS, but could increase grip due to better camber control if the car isn't well designed for performance driving). The rear axle will have less transfer, which will increase grip at that end (depending on camber control), and hence an understeer tendency is the result.

Even though the above general principles about ARB stated by Tristan are correct, we have to mention some inaccuracies that the LFS TLS model introduces, making the ARB bars not to have so accurate effects on FWD cars handling.
If you make a search you will find many refers to that problem.
Here is one of my last explanations to that effect.
http://www.lfsforum.net/showthread.php?p=769616#post769616