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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Sway and roll bars and braces - how should I tighten up my suspension?



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      10-31-2018, 03:09 PM   #1
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Sway and roll bars and braces - how should I tighten up my suspension?

I'm looking to tighten up my suspension, specifically body roll and rear step-out. Step up and make a suggestion!

Here's what I'm running right now on a 2009 335i with Sport package:

ST V1 coilovers
BC Forged 18x10 and 18x11 wheels with Pilot Super Sports (biggest I could fit)
M3 suspension: 11pc FCP Euro upgrade kit

I don't want the car to be any more harsh, I'm looking to reduce roll and provide a nice, predictable step-out characteristic in the rear. And yes, an LSD is on the list soon enough.

How should I change my anti-sway and anti-roll bars? Should I upgrade the strut tower brace in front? Rear (if there even is one stock)?
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      10-31-2018, 03:57 PM   #2
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M3 or firmer rear subframe bushings, Megan racing rear toe arms, firmer differential bushings will tighten up the rear end.
For body roll you can lower your car, get a quality coilover suspension or larger sway bars, M3 or Dinan.
Strut tower brace is useless unless it's a track car.
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      10-31-2018, 04:07 PM   #3
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Quote:
Originally Posted by cvc 22349a View Post
M3 or firmer rear subframe bushings, Megan racing rear toe arms, firmer differential bushings will tighten up the rear end.
For body roll you can lower your car, get a quality coilover suspension or larger sway bars, M3 or Dinan.
Strut tower brace is useless unless it's a track car.
As you'll note, I already have quality coilovers. ST V1s are the same as the KW V1s, just galvanized steel instead of stainless, and it's already lowered.

I'm not interested in a harsher suspension, so I'm trying to avoid the subframe bushings. Forgive my ignorance, but what do rear toe control arms do for me?

For sways, what do you think about the H&R kits (27mm front 20mm rear (Search "Sku # : HR_Swaybars_E90_PR" since I'm pretty sure I can't link to m o d b a r g a i n s)) vs the Hotchkiss (https://www.turnermotorsport.com/p-5...way-bar-kit/)?
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      10-31-2018, 04:48 PM   #4
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You mentioned rear step out. If you want to reduce rear end side to side slop the rear subframe bushings are the primary culprit along with the toe arms.
I don't have experience with those sway bars and think they're too stiff.
Yes I saw you have V1's I had KW's once too.
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      10-31-2018, 04:54 PM   #5
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Quote:
Originally Posted by cvc 22349a View Post
You mentioned rear step out. If you want to reduce rear end side to side slop the rear subframe bushings are the primary culprit along with the toe arms.
I don't have experience with those sway bars and think they're too stiff.
Yes I saw you have V1's I had KW's once too.
Yeah, they're not Tein Electronically Controlled, but the work well enough.

And ah, thank you. My understanding of suspension is fairly basic, and I'm trying to learn more.

I did some reading and found that the Eibach set is more street oriented (Part number 2085.320). What do you think?
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      10-31-2018, 05:43 PM   #6
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The Eibach kit looks better kind of like Dinan. I have a BMW PS front sway bar and 14mm rear sway bar. Sway bars are the last thing you should address but make sense since you have a lot of tire.

If you want an understanding of our suspensions go back to 2007, 2008 and check out rear subframe and control arms by 'Orb' and HP Autosport. M3 rear subframe bushings or inserts won't hurt your ride quality, they will improve it along with reducing rear end slop. It is the best modification for these cars that aren't running runflat tires. If you replace the bushings with harder rubber, poly or solid mounts that's the time to replace the rear sway bar.
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      11-01-2018, 10:50 AM   #7
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I found a set of Eibachs new-in-box that I'm buying, but it'll be a while before I install them due to needing to drop the rear subframe. I'll probably wait until I pick up an LSD (April-ish) and do it then.

I'll look into the bushings. Thanks a bunch for your help (and enjoy some fresh Blue Bottle for me, I love the Bay)!
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      11-05-2018, 06:50 PM   #8
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Sorry to hijack/deviate, could you post a picture of your vehicle with the BCForged's and post your specs? Highly interested in getting a set myself.

Thanks!
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      11-06-2018, 07:12 AM   #9
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Until you get the rear bar/LSD installed, put the front one on...it only takes like ~30 minutes from start to finish and makes a big enough difference on it's own to make it worth while.

What tire sizes are you running? To get the car more neutral go with a squared wheel/tire setup next time instead of staggered.
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      11-12-2018, 09:36 AM   #10
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Quote:
Originally Posted by joeybutts View Post
Sorry to hijack/deviate, could you post a picture of your vehicle with the BCForged's and post your specs? Highly interested in getting a set myself.

Thanks!
Forgive the height; the wheels are wide enough that I need to roll the rear fenders and cut the fronts before I can drop it back down. These are Matte Bronze RZ05s.



Matte Bronze RZ05 wrapped in Pilot Super Sports
18x9et30 front 245/40/18 with a touch of camber
18x10et35 rear 275/35/18 no camber with fender roll

I was very, very specific that I did not want to run stretched tires at all.
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      11-12-2018, 09:36 AM   #11
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Quote:
Originally Posted by FCobra94 View Post
Until you get the rear bar/LSD installed, put the front one on...it only takes like ~30 minutes from start to finish and makes a big enough difference on it's own to make it worth while.

What tire sizes are you running? To get the car more neutral go with a squared wheel/tire setup next time instead of staggered.
Given the cost of the wheels ($2800 a set), that's not very likely at this point. Tire sizes in post above.
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      11-12-2018, 11:49 PM   #12
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I have solid aluminum rear subframe bushings, 11 piece m3 front and rear arms, manzo toe links and eibach front and rear sway bars going in this week. Will post results once I get the car back and aligned
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      11-13-2018, 01:21 PM   #13
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Beautiful and thanks for sharing!
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      11-13-2018, 04:12 PM   #14
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Quote:
Originally Posted by hellokitty View Post
I have solid aluminum rear subframe bushings, 11 piece m3 front and rear arms, manzo toe links and eibach front and rear sway bars going in this week. Will post results once I get the car back and aligned
Looking forward to it! That's the same setup I have except the bushings and toe links.
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      11-13-2018, 04:13 PM   #15
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Quote:
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Beautiful and thanks for sharing!
Thanks man, I appreciate it!
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      11-14-2018, 09:45 AM   #16
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Quote:
Originally Posted by FCobra94 View Post
Until you get the rear bar/LSD installed, put the front one on...it only takes like ~30 minutes from start to finish and makes a big enough difference on it's own to make it worth while.

What tire sizes are you running? To get the car more neutral go with a squared wheel/tire setup next time instead of staggered.
I thought installing one without the other upset the balance of the car, exaggerating the rear sloppiness?
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      11-14-2018, 09:50 AM   #17
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      11-14-2018, 11:05 AM   #18
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Quote:
Originally Posted by cvc 22349a View Post
M3 or firmer rear subframe bushings, Megan racing rear toe arms, firmer differential bushings will tighten up the rear end.
For body roll you can lower your car, get a quality coilover suspension or larger sway bars, M3 or Dinan.
Strut tower brace is useless unless it's a track car.
Pretty much this. I would also suggest shock mounts if your shocks use oe style rubber.

I found a front strut bar incrementally useful, although I HPDE and track my car 5-6 times a year.

The stock SF bushings are literally crap. M3 bushings will make no perceivable difference in NVH.
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      11-14-2018, 09:50 PM   #19
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Quote:
Originally Posted by hellokitty View Post
I have solid aluminum rear subframe bushings, 11 piece m3 front and rear arms, manzo toe links and eibach front and rear sway bars going in this week. Will post results once I get the car back and aligned
Please share some feedback on those solid rear bushings!
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      11-15-2018, 09:37 AM   #20
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This is what I just installed. M3 subframe bushings, trw 11 piece m3 arms, Megan racing toe arms. M3 diff bushings and some st xta coil overs. Talk about a big improvement. When I launch now the car goes straight. The ride is getting better everyday. Will do a full review after a month. I want the car to settle 1st. It took me 2 days to install everything. $3k in parts. But I'm truly happy.
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