antiroll bars & bushes

General General Lotus Talk
1

i’m not 100% happy with the way my exige turns in, it seems push the front, was looking at the aftermarket antiroll bars and bushes on exliseparts, anyone tried one? i’m no expert but i think this would improve things a bit would’nt it.

2

do not forget that more is the front antirollbar the more your car will understeer…Nicolas

3

Have you tried playing with the existing front roll bar settings (apparently quite easy)?You could play a little with tire pressures for a cheap basic slightly alteration.People in the past have commented that understeer occurs in the Exige if you don’t go in quick enough (disclaimer - I am not responsible for any damaged caused using this method).Ian [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]

4

I am not totally 100% familar with the Exige yet, still only had mine for a few months now, but…wouldn’t adjusting the camber of the wheels also help reduce understeer? i.e. adding 1/2 deg. of negative?I seem to remember Trevor doing this on his Exige,and when I test drove his, understeer was pretty much non existent.-Gman

5

I think most Exiges in std trim are fairly neutral Mine came from new with a very neutral feal but I prefer a little overstear so I dropped the roll bar back one notch(softened) contrary to all the rules and now find it is just perfect for me It only takes 10 mins to change give it a try before you spend any money [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]JohnCPersonally I like the go faster theory[This message has been edited by JohnC (edited 27 March 2003).]

6

what u did is not contrary to all the rules,it works like this!Nicolas

7

That’s what I thought too Nicolas, but I wasn’t going to argue ! haha

8

Don’t try to use conventional wisdom about ARB’s on the Elise, it does not work!The stiffer the front ARB, the less understeer you get, there is a long and boring reason for this, I will not go into here, but suffice to say that stiffening the ARB works.Other thing is that to get rid of the initial turn in understeer, just set the front toe to ~0�15" toe OUT total.Simon (S)

9

I have my Elise set up as Simon suggests. Stiff ARB and ~0�15" toe out at the front. Front end turn in is astonishing. Now…if I could only sort out the bumpsteer :wink: Bri

10

I’m thinking of fitting a stiffer and adjustable antiroll bar.

Don’t try to use conventional wisdom about ARB’s on the Elise, it does not work!The stiffer the front ARB, the less understeer you get, there is a long and boring reason for this, I will not go into here, but suffice to say that stiffening the ARB works.Other thing is that to get rid of the initial turn in understeer, just set the front toe to ~0�15" toe OUT total.Simon (S)

Is this true, and if so, can anyone provide the ‘long and boring’ explanation?

11

Anyone???

12

The old wisdom of stiffening an anti-roll bar, decreasing grip is generally true, but it’s only when looked at from the perspective of that particular end of any car being perfectly neutral to start with.

Elises and Exiges out of the box are a little softer in roll stiffness at the front than this ‘perfectly neutral point’ and probably as equally importantly it’s softer than the rear and so the front tyres aren’t worked as hard as the rears are.Increasing the front ARB effort gives it this extra roll stiffness and works the tyres harder giving more front end grip.

hth

13

The stiffer bar promotes an increased level of response so on initial turn in it will feel grippier, however on a longer high speed bend it will start to understeer slightly more.

Interestingly I recently drove an Elise r with the front bar disconnected. Overall front grip wasn’t affected much but turn in response was worse as was roll angle. Steering feel and initial precision was worse.

14

By stiffening an antiroll bar, you are reducing the amount the vehicle rolls (obviously!) and this contributes to the amount of weight transfer you get.

In a nutshell, the amount of grip a tyre produces is, amongst other things, proportional to the mass acting on it. However, it is not directly proportional. For example, doubling the mass does not double the amount of friction available, (it would be less than double). You are therefore losing a reaction force on the inside tyres, which is not quite made up for by the reaction force gained on the outside tyres, therefore, less overall grip.

The portion of weight transfer attributed to body roll would reduce with a stiffer anti roll bar, therefore minimising the loss of grip.

However, it is also worth considering that bodyroll promotes more suspension movement (obviously), and the suspension geometry frequently promotes more negative camber on bump, giving more cornering force.

All very complicated!! Its a trade off, and varies from vehicle to vehicle.

This explains tyre mechanics a bit more in depth. Enjoy!

http://www.macgracing.co.uk/trackdays_setup1.html

Jonny

15

Is it an S2 ? Also, are we talking about road or track driving here ?

I have an Elise S2 and its awful on the road for understeer but it completly dissapears on the track when the tyre temps go up. It still doesnt turn in as well as a caterham for example but I can live with that (for now).

16

S2 MY05, mainly road with the odd trackday. Just thinking out loud really.

The pictures from a Donington trackday showed significant roll with two up, and much more would probably have made contact with the bump stops, at the front anyway.

Understeer was, as you say, not a problem once the tyres were hot and Craner was flat once I’d plucked up enough courage.

Thanks to all for your responses.