Sway Bar Preload

[pastaroni34]

To any of the chassis set up guys who know more about this than I do:

Is sway bar preload actually important? I've seen many products in the marketplace talking about adjustable sway bar links to adjust your sway bar preload. Is the effect really significant? Anyone see a noticeable difference with or without them?

Secondly, I have never seen an OEM concerned about this. Do they always assume a 50/50 weight distribution left/right to ignore preload?

Thanks for your help.

[mtbr]

I generally set the car up for ride heights and corner weights with the anti roll (sway) bars disconnected and then adjust the drop links so that the corner weights are not affected.

i.e. I am adjusting the bars so there is no preload.

[Guy Croft]

You must set up a competition car with the body and suspension and all supporting frames to the unsprung regions (in their entirety) in their free state ie: not do handling adjustments before locking up all the members (incl sway brace). Deflections caused by tightening up the fixings and/or inducing preload (from screwing-out/extending things like sway bars) could - technically - impact unpredictably on the handling. You can induce understeer that way - by stiffening the front end by any means, eg: stiffer dampers, springs, and yes fitting a sway bar. Naturally, a road car is far less sensitive to alterations than a single seater, the latter being super-sensitive - and they need to be as any driver of same will tell you.

What you mustn't do with stiffening/strengthening devices like a sway bar is push the body out of its design shape - and you can do this quite easily, better to have the body jigged and seam welded first to identify its true design shape and then fit the device, measuring with dial gauge to ensure that it doesn't deflect the body in the static state. What you want to assure is that the device restrains the body to its er, 'correct' shape - rather than actually deforming it.

That said, doing what I have described is beyond the means (and need) of most not actually engaged in top-level competition.

GC