Just been having a look a front roll centre adjusters.

Cheapest I have seen them is

 

Agree, can't see any issues with that method.

 

Is that a ring.................... NO it fecking ain't.

Stop all buying until ring is secured (End of Jan)

Kiwi

 

Just so I understand, and sorry for jumping on the thread, what is a roll centre, and why would you want to adjust it?

 

In principle I'd agree
Not that I'd have the confidence to rely on "a longer bolt and spacers" though
Have a chat with Chris @ CG he is probably knowledgeable enough to confirm or deny your idea!

 

The theory is that when you lower a car with coilovers or springs, it rolls more (assuming the spring rates aren't increased, which in practice is not usually the case) because the roll centre is moved due to the resulting modified suspension geometry. The roll centre adjusters correct the geometry and move the roll centre back towards the original position.

Ron's pictures show front RCAs, the rears are slightly different.

Chris.

 

Lowering this car puts the roll centre LOWER not higher.
Think of it as a pendulum effect, with a big weight hanging beneith the car.
Lowering this car lengthens the pundulum, so it has more 'virtual twist' effect on the cars roll.

So, you think lowering a car makes it roll less? Wrong.
Lowering a car drops the centre of gravity a little so you get less roll.
But, lowering a car with double wishbones a lot (S2000) also drops the roll centre a lot more than the C of G, causing more pendulum effect.
The pedulum effect far outweighs the gains in lowering the C of G so the car rolls even more than stock.

Lowering springs are normally stronger so they sort of cancel out this effect a bit. The end result can be a car with massive strong springs that rides as hard as hell yet still rolls like stock!
Its a function of the angles of the wishbones in the suspension and the lean angle of the car.

There are gains to be had in lowering up to a point.
Beyond that when the roll centre (imaginary point) falls below the road level then roll is increasingly worse.

The roll centre adjusters Ron aludes to alter the angle of the lower wishbones - making them angle downwards more at the outer ends.
This is done by making the balljoint further away from the wishbone, just like the bumpsteer kits do with the rear toe arm balljoints. (see Rons pics above).

Ron - those balljoints (J's racing?) are also available with a lateral offset holes to give more camber.

 

That is exactly how Chris @ CG explained it to me.
However here is a pic of mine 35mm lower on decent coilvers cornering hard @ Anglesey, no roll there!

 

Wow, how planted does that look

The limit is now definately the tyres

 

Again, I was thinking about this roll centre mismatch the other night.

Like Steve said, it is the distance differential between the Roll centre and the CoG that is producing the torque force to lean the car.

However...

If the CoG is lower than the Centre of Roll the the effect sould be opposite, no?

Think about it - simple levers and all that.

Try it. Grab a pen/pencil and hold it in the middle. The place you hold it becomes the Centre of Roll.

Now, use your other hand to push the pen at the top (CoG above CoR) and the bottom (CoG below CoR).

The rotation is different.

I know I have immensely simplified automotive dynamics here, but if someone is willing to add the additional factors, i'd be welcome