'longitudinal' sway bar?

[artcat]

I was wondering if a 'sway bar' conected front to rear on one side would give an advantage on circle tracks where you are braking and turning. The idea would be to transfer weight to the inside for braking when the nose dives , and maybe it would help with powering out also.

Screwy idea? Illegal?

 

[MikeHalloran]

I think the '54 Packard had something like that.



Mike Halloran
Pembroke Pines, FL, USA

 

[BillyShope]

Keep in mind that the lateral "weight transfer" is a function of only the total weight, lateral acceleration, and CG location. This is determined by a free body diagram of the whole car. There's nothing that can be done "internally" to change this. (Perhaps that's not what you were getting at, but that's the idea I got from "transfer weight to the inside.")

 

[BillyShope]

Okay, I see where it could be used to change the cross during braking. Can't see any advantage over the more common method (different LF and RF spring rates).

 

[GregLocock]

I can see that it might be worth it when accelerating out of a turn, but on the way in:

brake
load on front tires increases
antipitch bar (which will work just like antidive, but slower) starts to take effect
load on front tire increases, braking increases (good)
driver feathers off brake as he feeds in steering wheel
weight on front wheel reduces
car doesn't turn

Oh dear.

On average, around a circuit, ignoring aero, the vertical load on each wheel is unchanged by any internal reconfiguration that does not move the CG or change the weight, wheelbase, or track. So you can generate short term changes in the load on an individual wheel, by any number of methods, but at some point you'll have to pay it back.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Yawing]

Yes this is true, the bigger the oval, the less benifit is has, as the longer time you need to laterally accelerate the car without the longitudinal acceleration. Meaning a longer time when this device will do nothing at all.

If it was a very short sharp corner, where you are almost still braking right into the apex, then going straight to power (it would have to be more like a hairpin) this could be of benefit, as you would gain on front grip into, and rear grip out of the corner.