anti roll bars doubt

[roadracing101]

I was just going through my basics. My doubt is if we
increase the roll stiffness then the body roll should decreae and hence lateral load transfer should decrease
If lateral load transfer decreases then when applied to the front axle the understeer capabilities should decrease as the load is it has enough lateral force to do the corner without an increase in slip(load sensitivity of tyres)

[wil oberlies]

Holy run-on sentence.
Lateral load transfer occurs without roll angle; it's a function of a vehicle having a CG location above ground level and a finite track width. I think what you're suggesting is that by reducing the roll angle, you'll have some (significant) reduction in lateral load transfer. This implies the CG is moving quite a bit....
Increasing front roll stiffness could decrease understeer by reducing the amount of camber change, keeping the wheel normal to the road surface.

[Will M]

Indeed, I’m not sure exactly what he is asking.
Roadracing101, could you rephrase your post as a question?
Also, check your inbox.

-William

[roadracing101]

Sir I read that lateral load transfer occurs due to two mechanisms-
1)Because of cornering forces(instantaneous)
2)Lateral load transfer due to vehicle roll
Now if vehicle roll is reduced by anti roll bars,
Then lateral load tansfer should be reduced by the same.
So if we install an anti roll bar on the front axle, Then it should reduce the understeer.
But the opposite happens that is understeer increases if an anti roll bar is installed on the front axle

[Max Trenkle]

I think he's under the impression that if you 'eliminate' roll, then you 'eliminate' load transfer.

Go-karts don't have any suspension (the frame does twist a bit, but pretend it doesn't). Do you think the load on the tires stays the same in a corner?

Another good example: when you are driving and you turn a corner, you usually clench a butt cheek to keep your body straight up and down. You clench because the forces demand it. So your body is still straight up and down in a corner, yet there is more force on one cheek than the other. :P

[Will M]

Roadracing101,

I think you have your cause and effect reversed.
Check your free-body-diagram.

-William

[roadracing101]

In my free-body diagram, I wrote the moment equation at roll center for the unsprung mass.

The weight difference on the two tyres was a sum of two terms-
term 1) 2*fy*hr/t
fy-lateral forces;hr-roll center height;t distance between tyres
term 2) 2k*(roll angle)/t k is roll stiffness

I know lateral load transfer on tyres because of cornering forces is instantaneous and will occur even if their is no chassis roll.
However if we increase the roll stiffness then wont the load transfer due to chassis roll decrease?

[acedeuce802]

Originally posted by roadracing101:
However if we increase the roll stiffness then wont the load transfer due to chassis roll decrease?
No. Load transfer is not based off of chassis roll. Like other said, that would only be true if the CG moved drastically under roll.

[Owen Thomas]

I am not certain if you are phrasing it correctly, but the answer to your last question is "yes", as I understand it. To get a better understanding you should read up on the difference between Geometric and Elastic weight transfer - this confuses a lot of people.

When the body rolls your CG location changes, which in turn changes(increases) your weight transfer. So, like you said, the instantaneous lateral load transfer stays the same, but with less body roll you will have less "extra" load transfer. For all intensive purposes, I believe this is mostly negligible though.

[Dettle]

Well I think you just need to go on reading and try to understand the basics. The weight transfer is only dependant on the ratio of Center of Gravity (CG) height to track width, the vehicle mass and of course, the amount of lateral acceleration! The effect of CG position is very small and is not what you're adressing in your question.

Some hints:
-Lateral acceleration acting on the suspended vehicle body can and very often will cause a body roll moment
-body roll moment is dependant on vehicle body weight and the moment arm (distance CG to the body roll axis)
-in steady state (lat. acceleration is constant) this roll moment is reacted by the suspension springs and the Anti-Roll-Bars
-increasing a spring stiffness will decrease the spring deflection for a given Force --> here you have the roll moment given --> hence increasing your roll stiffness will reduce your roll angle.. and nothing more!
- But: you can influence the distribution of your weight transfer by changing the distribution of your front to rear roll stiffness! Make your front end the harder spring in roll (e.g. by increasing ARB stiffness) and it will transfer more load on that axle while the rear will transfer less load (the sum stays the same!!)

Again, keep on reading and try to understand the basics. Or try it yourself with simple drawings and imagination.

Regards

[roadracing101]

Thank you everyone. That did clear some of my confusion.