E82, E90, E92, E93 Front Sway Bar Upgrade Comparisons
BMW made a lot of changes in the front suspension for the E82 1-series and E9X 3-series. One area where they improved on past suspensions is by using hollow sway bars to reduce weight. And to further tune the handling the bar, sizes were varied among each model. We have collected the various stock sizes along with an H&R M3 bar and gave it all to one of our suspension engineers to draw some direct comparisons.
All of the E9X front sway bars are interchangeable so you can pick and choose which bar will work best for your particular application. The E93 M3 cabrio bar is the largest outside diameter - BUT it narrows down to 24mm in the middle and it's hollow. Both will reduce it's effectiveness. You can see that the stock E90/E92 M3 front bar is a straight 26.5mm throughout it's entire length. So the difference between the two is pretty small on paper. Either one would be an upgrade over the stock non-M E9X bar. But if you want the stiffest, the H&R is clearly superior because A) it's a straight 27.0mm diameter across its length, and B) it's a solid bar, not hollow, so it resists twisting a lot more.
Sway bars contribute to the overall spring rate of the suspension. Going with too large/stiff of a bar will impact the handling balance and ride, especially with stock or mild sport springs. So you don't always want to install the biggest and stiffest bar out there. Careful consideration of the rest of your suspension and even your tires is recommended. For a E9X non-M street car, with stock or sport springs, we would probably recommend a stock M3 or the E93 M3 front bar because we know it works well in this application and it's guaranteed to be an improvement with minimal downsides. If you use the H&R M3 bar on the street, you should balance it with the H&R M3 rear bar. And if you're building a track car with stiff springs, or already have an M3, the H&R bar is clearly the best choice.
Here are the specs on the individual bars:
Stock E90 M3
|E9X non-M||31 35 6 796 302||26.5-23.0mm||Hollow||n/a||-6.51%|
|E90/E92 M3||31 35 2 283 515||26.5mm||Hollow||+6.96%||n/a|
|E93 M3||31 35 2 283 965||28.0-24.0mm||Hollow||+13.12%||+5.75%|