Eibach Sway Bar Settings

MaysEffect

You are right to think that, essentially the open variable is tire grip, if you don't have tires that have enough grip, having a large front ASB will overload the outside tires and cause the car to start to slide....overheat..slide some more. Additionally, having rear tires that simply have MORE grip than the front will also lead to a similar problem. With a oem type staggered setup, the care tends to naturally want to understeer a bit more for the later reason, thus some people choosing a larger rear bar.

Spring rates is often the contributing factor, as you can overcome similar issues of roll/dive/squat by using stiffer rates rather than using a swaybar, but this does not give you the added benefit of cross weighting. It's all a balancing act between these factors. Tires being a major proponent in choosing the correct balance.

Making the front stiffer is to do the exact opposite to the problem above. If a car naturally oversteers, it's most likely because the front tires have more grip than the rear (or the rear not having enough). This can happen by running a squared setup, a mixed tire setup (softer tires on the front) or a weight balancing problem...A very distant but equally important problem would be tire pressure and heat issues. Because our cars are weight biased slightly to the front, the rear will tend to slide out early in the turn causing a quick sensation of oversteer. Adding a larger front bar can balance this out for several reasons, ultimately it's done by increasing understeer slightly and cross weighting which allows the rear to sit (squat) into the corner. This is what Gomer described. IF the car still tends to understeer too much, then you probably do not have enough front grip or the spring rate is not optimized for the sway bars & corner loads.

This is a question of tires and alignment. IF you already have these parts installed and you are not getting what you want out of them, you may want to look into alignment settings and getting better tires if you don't already have something good.

Are you having a problem with turning accuracy? Mid corner grip?, bump stability?

A larger/stiffer front bar should help tame steering speed and thus oversteer moments. Conversely a larger rear bar can help turn in speed and agility all things being equal. You can tune your alignment and tire setup to make either work. Overall a larger/stiffer rear bar is less stable, certainly without significantly higher levels of downforce and tire grip.