These have always puzzled me!

I understand what they do and how they do it, but could body roll not be controlled by just using stiffer springs on the dampers???

Can someone in the 'know' explain in numpty-terms why they are used in conjunction with a set of coil-over dampers?

You don't in theory need them for a track car as you can control body roll just with springs

However they make adjusting the load transfer front to rear a lot easier and cheaper than changing springs. i.e dialing understeer/oversteer in and out

For road cars they were a simple way of allowing softer springs for ride comfort and not letting the car roll too much.

What an engineer would really like is to completely decouple roll bounce and pitch and control them all seperately.

Unforunately an antiroll bar doesn't just work in roll it, so if you put a fat one on ride comfort will be really bad when the wheel are going in different directions

[Edited on 29/5/12 by mikeb]

Cheers Mike... that's pretty much the conclusion I'd drawn up in my head.

But I still see plenty of pics of very focused looking single-seater race cars with ARB set-ups.

Stiffer springs would do a similar job, but stiffer suspension would have other reprecusions, so bhy using anti roll bars it gives the flexiblity to have a softer set up yet still control body roll. There is also a compromise with grip levels as its common for an anti roll bar to lift the inside wheel causing less traction! Ive always felt they are better on track than on road, as it tends to be roads that have more uneven surfaces leading to more likely loss of traction than on a nice smooth level track surface.

You could also look at mono-shock setups... No ARB at all..

i.e. http://www.scarbsf1.com/Monoshock.html

You would only need 2 shocks on you trike.. With control of roll. No idea if it would work well on the road (probably not!)..

[Edited on 29/5/12 by Bluemoon]

One of the main reason why RWD cars nearly always have front anti-roll bars is that it allows the car ride bumps with less pitching ie the bucking bronco effect.
If a front anti-roll bar is used then the front spring frequency can be reduced (by making the front springs softer) this means the front and rear of the car will level out and land at the same time as it passes over a bump. The relationship between the front and rear suspension frequencies is worked out by a formula based on the design speed of the car and the wheel base.

On fwd cars you will often find a rear anti-roll bar because they car so high a % of the mass at the front that getting the car handling balanced without one would require making the rear springs so hard the ride would be foobared.

[Edited on 29/5/12 by britishtrident]

quote:

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Originally posted by Bluemoon
You could also look at mono-shock setups... No ARB at all..

i.e. http://www.scarbsf1.com/Monoshock.html

You would only need 2 shocks on you trike.. With control of roll. No idea if it would work well on the road (probably not!)..

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I just can't get my head around why you would want to have an independent suspension... but then directly link the two opposing wheels with an ARB.

Independent suspension really isn't that important a de Dion axle is every bit as good as a fully independent rear end but de Dion is very awkward to fit in..

I'm only really thinking about the front-end BT.

An ARB is twice as stiff in roll as it is in single wheel bump.

No suspension is independent in reality. There's a great big torsion bar, usually called a chassis, connecting all the wheels together.

Here's a good comprehensive article on the subject:

http://iracing.wikidot.com/components:anti-roll-bar-sway-bar

My simplistic explanation would be to say that and ARB allows control and adjustment of body roll without requiring excessive stiffness in the springs. You want the springs and dampers to be set up to handle bumps as best they can, taking account of unsprung mass and tyre characteristics. The ARB is a separate mechanism which can be used to control body roll which is important to ensure the tyre contact patch is consistent without having massive amounts of negative camber. Negative camber can counteract some body roll but it should be borne in mind that lots of negative camber will compromise traction and braking when in a straight line and can overheat the inside shoulder of the tyre.