[ObsidianX]

I have a stock 2011 335i xDrive. I want to do a few upgrades to improve performance. One of my thoughts is to replace the OE rear sway bar with the 23.6mm width M Sport rear sway bar. This is the kit at ECS Tuning: https://www.ecstuning.com/BMW-E90-33...ade/ES2622885/

Has anyone done this? Is it worth it?

[feuer]

Not needed nor recomended.
Stiffer rear sway bar will result in rear end loss of traction.
Leave rear sway bar alone.
If you want to reduce body roll look into stiffer springs and better dampers.

[ObsidianX]

Thanks for the reply.

[brocklanders]

I just want to throw a different opinion in here. I've had two e90's and an e82, and I have swapped the sways on all of them. I buy and drive these cars because of the way they drive and how that makes me feel not because I'm a professional or amateur driver trying to get my best lap times. As far as I know it is true that a stiffer rear sway bar will decrease grip on your rear tires at or near the limit. Since I mostly drive on the street and never bring my rear tires to their grip limit, I like the feel a stiffer then stock rear sway bar gives me. I did not however go with the M3 sway bars, I used eibach on all of my cars, my theory was they keep the front to back bias very close to stock while being large enough to make a difference. Although I have no experience with AWD I thought it was okay to use stiffer sway bars.

[Tom Droze]

With the expense involved in replacing the rear sway bar, and if you truly want to improve the handling characteristics of your car, I would recommend replacing the run-flat tires with a quality non-run-flat tire like the Michelin PSS. I would also recommend upgrading the shocks and perhaps the springs too.

[brocklanders]

Originally Posted by Tom Droze

With the expense involved in replacing the rear sway bar, and if you truly want to improve the handling characteristics of your car, I would recommend replacing the run-flat tires with a quality non-run-flat tire like the Michelin PSS. I would also recommend upgrading the shocks and perhaps the springs too.

This may be true, I run eibach sways with swift springs, bilsteins, poly subframe bushings and Dunlop zII's. But I installed the parts myself which saved me over $1k. The car feels like a go kart, it may not run as fast around a track as it could but for what I use it for I like it. So much I did it three times, every time I got a new car.

[ObsidianX]

Thanks for the additional thoughts. I plan to drop the run flats and use Michelin PSS for my summer rims and Continental DWS 06 in the winter. I currently have 17" Style 284 and am thinking of picking up a square set of 18" Style 400M rims. OE with 284 are 225/45R17 but I would like to go 235/40R18 on the 400M.

I personally find the ride height fine and don't really want to lower my 335i xDrive. What do you recommend for shock/strut changes? Bilstein B8?

[gtaccord]

Actually I would not recommend the 23.6 mm rear M sway bar (found on the e93 m3) but the 22 mm version (found on the e90/e92) is the more typical upgrade and imo really improves the overall handling characteristics of the car. I would not do this mod without first getting better tires and upgrading the springs and shocks

[tetsuo111]

It's just engineering - suggest considering what it is that you want to accomplish first, so that you can choose a solution that gets you there. What do you want to get from a bigger rear sway bar? Trying new stuff can be fun, but can also be a quick road to disappointment and angst. Ask me how I know (not this hobby, but the same principals apply).

If you don't track your car, then what Feuer and Tom Droze said. ARBs, properly used, are simply a tool for fine tuning the balance. If you want less roll, consider firmer springs first.

On the other hand, if you have the resources and want to try new sways, go for it! It's your ride. But as Tom Droze said, the install is $$$ because the subframe is dropped. Big job, big labor. Remember to schedule an alignment, too. My car had the treatment last summer to install RSBs and Diff bushings. I track my car, and chose not to change the rear sway while it was convenient. No regrets.

IMO though, a bigger rear sway will result in even more push and less traction. But your cornering will be flatter.

[gtaccord]

This is not true on the xdrive cars. A bigger rear bar does not produce more push on an xdrive car.