Suggestions needed: Spring rates/no swaybars for E30 318is

[Jean]

Start by thinking about how a rear sway bar works. It links the rear wheels with what amounts to an extra spring. So for example, when you hit a bump with the right wheel, the left wheel is pulled upward by the sway bar.

With me?

Now think about what happens when you're cornering and your car rolls to the outside of the corner (centripetal force). The same effect applies... the inside wheel will be... LIFTED. Two tires have the most grip when they share their load evenly... when one is totally unloaded it's not doing its part, and if you have an open diff, that wheel is hanging in the air spinning.

The bottom line is that sway bars are used to tune the balance of a car's suspension (notice that most cars have thick fronts and skinny rears stock... understeer) at the expense of grip. Exchange the swaybars for stiffer springs (which will also reduce roll, but won't effect weight transfer in the same way) and you can pick up grip.

Ever see a VW lift its inside rear tire? Too much rear sway bar to overcompensate for a FWD car's natural tendency to understeer.

Actually most but not all older VW's lift inside rear as the rear end is solid flex beam, even with stock suspension you can easily get it to lift it's rear. (had an 03 gti).

[matt]

Well, either way, if the inside tire is off the ground, they're giving up rear grip in favor of balancing the car away from understeer.

[325is///M-tech]

We had 500lb front and 550 rear but they were 8 years old and worn out so we went with 600 front and 650 rear.

[Jean]

Well, either way, if the inside tire is off the ground, they're giving up rear grip in favor of balancing the car away from understeer.

Now if the front tire is lifted on a rwd car, does that mean it's giving up front grip ?

[Bavarian3]

I think there is a lot of info, good and bad. The one thing that was not talked about was shock settings. We are assuming that 600 spring rates will be perfect with non valved shocks. The setup also depends on how the track is as well. That being said, I am running around 700 lbs front and 1024 lbs rear springs. Stock M3 front bar and no rear bar.

[matt]

Now if the front tire is lifted on a rwd car, does that mean it's giving up front grip ?

Yep.