Adjustable anti roll bars

[DaveK]

Peter

 

If you made a front anti roll bar with a blade at each end would this effectively give you double the adjustment of the bar.

 

Would the blades have to be adjusted equally or could you have different angles each side.

 

The roll bar stiffness could then be rated by the dia/wall thickness of the centre portion of bar connecting the two blades.

 

Thanks

 

Dave

 

[Alex Wong1697456877]

Dave,

 

From what Peter's saying, I think you're right in that you would have twice the adjustment but the maximum stiffness of the bar might be more or less than one with a single adjustable blade. You'd gain alot of softer settings though so when combined with a thicker ARB, it might ba a good solution, although a confusing one as it's difficult to know which combinations are stiffer and which are softer. Is 2-2 or 3-1 softer etc...

 

Alex

 

(feeling very inadequate after Peter's contributions!)

 

Edited by - Alex Wong on 13 Dec 2001 00:41:27

[wag]

Has anyone driven a car with the ARB on different settings each side? To quote Kilroy, "How does it feel?"

[Peter Carmichael]

Well now I feel tempted to throw the cat back in amongst the pigeons.

 

The jacking effect I mentioned occurs on the centreline of the car. If the centre of gravity is on the centreline, then the cornering manouevre that causes the car to jack up will be resisted more than the cornering manouvre that causes the car to jack down. Asymmetric roll behaviour because you are raising and lowering a weight.

 

However, the centre of gravity need not be on the centreline of the car. In my example the asymmetry resulted in 3.4mm of movement at the RHS and 10.6mm of movement at the LHS, with the suspension pickups separated by 800mm. This means that the roll axis is in line with a point 205mm to the RHS of the centreline - if this were to coincide with the location of the centre of gravity then you would get symmetric roll behaviour despite the asymmetric loadings.

 

Obviously it is not as simple as that. The front axle has a roll centre on the centreline. The roll axis will be inclined away from the centreline of the car.

 

So all of you who spend a lot of time in the car on your own should consider trying going one or two settings stiffer on the RHS of your rear ARBs. If you can tell the difference I will be amazed.

 

Edited by - Peter Carmichael on 14 Dec 2001 13:12:00

[dogvet]

I assumed that the springs required were dependent on the rate required for the weight of that corner of the car, and related to the angle of the shock from chassis to the wishbone. The ARB then contolled roll as it extremely potent in leverage terms, and the damping is the most important to keep the wheel from "bouncing" and in contact with the tarmac.

Arb adjustment and not increase in spring rate per se is a better way of controlling roll. after dive under braking accounted for.