135i - Front M3 swaybar upgrade = TWO UNEXPECTED BENEFITS!

[Kgolf31]

Typically, a sway bar is the last modification that should be done to suspension to fine tune. You can add a bar though on stock suspension fine. I had a 30mm solid bar on my Z4M with stock springs and dampers

However, the statement that will only cause more understeer isn't the case. A front bar helps weight transfer to the rear wheel, thus only increasing rear traction...Camber up front will eliminate the negative effect of understeer

[1Pirate]

Originally Posted by dcaron9999

Thanks for this feedback! Been thinking about sequence of optimal suspension tweaks for a while. Ive done M3 Front control arms, Ground Control Camber plates, and M3 rear subframe bushings so far.

The E92 or E93 FSB has been on my short term list, along with rear upper control arms.

I have read a couple of threads where members claimed that the E92 or E93 Front Sway bar should not be done until dampers and/or springs have been upgraded (slightly firmer). The reason being is that the cumulation of stiffer springs and stiffer bar might be too much, and create a negative effect (ie: increased understeer).

I notice you have done all of these piece meal.

What year is your 1 series (2011+ MY came with the linear springs) 2009
Did you keep the stock M sport springs when you installed your Koni's? No, I replaced them with 2011 MY M Sport springs.
Did you get the FSB before or after the Koni dampers? Yes
Do you use your car on the track? No. I have another car that I autocross/track
Any signs of understeer? No.

My car is a 2009 MY. When I installed the Koni's I also changed my springs to 2011 MY springs (linear vs. progressive) I picked them up from a forum member who had changed to a coilover set up. The 2011+ MY springs make a huge difference in the rear of the car for those of us who had the progressive springs originally. The 2011+ springs literally take away the bounce in the rear.

My first suspension mod was the M3 E93 sway bar. I did the FSB right after I switched to aftermarket wheels and non run flat tires. I had no issues with increased understeer, only less body roll after installing the M3 E93 FSB. Next I added the M3 control arms and tension rods which help tighten up the front suspension and improves the steering feel. Then I changed the springs and dampers to the Koni Yellows. After that I added the M3 rear guide rods. Lastly I added the M3 sub frame bushings and upper links. My personal opinion is that the dampers are the worst part of the stock suspension. Overall I love my set up and my car rides just as good now as it did stock, but with a lot more control and feel.

[dcaron9999]

Originally Posted by 128Convertibleguy

Are they experienced in doing using that particular combination, or just theorizing? My take is that you'd have to go pretty far on a 1 series before increased front roll stiffness is not a good thing. The increase in front grip due to more favorable camber should outweigh the decrease in front grip due to increased weight transfer. So, no increased understeer. This isn't a race car with good camber compensation at the front.

But, I'm just theorizing too. So don't trust me, either. Trust the guys who have been there and done that.

Didn't mean to question you integrity, so sorry.

Just wanted some feedback on your sequence of events, and if you find the car just right after all this. I have 135i M-pack coupe, so chassis may react slightly differently than a convertible.

Im considering the E92 or E93 M3 FSB, and the M3 rear upper control arms very soon. Dampers and springs will have to wait for another year due to budget. I was undecided on which of these two mods to do first.

A Quaife LSD is also in the works shortly for a little more control on the track.

[yllwwgn]

Originally Posted by dcaron9999

Didn't mean to question you integrity, so sorry.

Just wanted some feedback on your sequence of events, and if you find the car just right after all this. I have 135i M-pack coupe, so chassis may react slightly differently than a convertible.

Im considering the E92 or E93 M3 FSB, and the M3 rear upper control arms very soon. Dampers and springs will have to wait for another year due to budget. I was undecided on which of these two mods to do first.

A Quaife LSD is also in the works shortly for a little more control on the track.

dcaron9999, I can tell you that having gone through different suspension setups/upgrades on prior cars (fwd, rwd, and awd) all cars react slightly differently to the "order" in which suspension changes are applied. With that said, there are TONS of members on here who have applied significant changes and shared their feedback (SB's, M3 arms, subframe bushings, coilovers, LSD's, etc etc. Hence why I use the button so much myself too .

My own opinion though, having just scraped the tip of the modding iceberg if you will, is that in adding the E93 SB 1st my "gains" far outweigh whatever the possible "tradeoffs" may be. Increased steering feel, quicker response, and a more "solid" daily driving feel. Could doing ONLY this mod possibly induce more steady-state understeer on a track environment? Basic suspension tech says yes, however that's for you to decide if you want to gear more for a street/track setup. For me personally the larger FSB is a win-win for me.

BTW, mine is a 2011 135i with the linear springs, so stock suspension other than the FSB, and I ditched the RFT's a while back. If/when I tackle the next part of the suspension, it will be the dampers and springs... in that order actually. And as I don't need the complexity of a coilover setup, brobably Bilsteins paired with BMWP, Cobb, or Swift springs.

[128Convertibleguy]

Originally Posted by yllwwgn

Could doing ONLY this mod possibly induce more steady-state understeer on a track environment? Basic suspension tech says yes

"Basic suspension tech" considers weight transfer only, and not roll induced camber change. On a racecar with a suspension designed with good camber compensation that works fine. I don't believe it works for most MacPherson strut cars, including ours.

[Simmons-Racing]

Why don't people go with a adjustable fsb?


Simmons

[gap]

Read through this before getting my M3 front sway bar. Had all 3 so thought a picture would be helpful. All 3 taper slightly in the middle and just before the 90 degree downturn. The M3 bar is the E93 31352283965 28mm bar.
Top: M3 bar 8 pounds
Middle: Performance bar 7.4 pounds
Bottom: stock bar 7.2 pounds

The M3 smaller, stiffer bushing are in the middle of the photo and the performance larger, softer bushings are off to the left.

Driving improvements are just as Yllwwgn stated in the first post.

[yllwwgn]

Gap, thanks for the 3 bar comparison, and pics are always welcome so thanks for those

[Gangplank]

This thread should be a sticky. I read through an ocean of front sway bar theorizing and "you'll shoot your eye out" type threads before I got to the real world experience offered here.

[all4bspinnin]

Awesome to hear you cured a rattle!! Its like solving a murder mystery case that's been open for 15 years lol.

Did you use your stock 1 series end links or E93 endlinks?