F30POST
F30POST
2012-2015 BMW 3-Series and 4-Series Forum
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > Suspension | Chassis | Brakes > Anti-roll (Sway) Bars Options study
Extreme Powerhouse
Post Reply
 
Thread Tools Search this Thread
      09-01-2017, 03:43 AM   #1
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Anti-roll (Sway) Bars Options study

I've put together a table of the available ARBs for our platform, BMW has quite a lot of options depending on engine, suspension, M Sport, M Adaptive or standard.

In a nutshell:
- 6 cyl get weaker front bars than 4 cyl engines
- M Sport has slightly stronger bars front and rear
- 440i LCI have stronger bars (same as M235i) than non-LCI 435i
- Xdrive have weaker front bars but same rear bars.

Aftermarket:
I've tried the H&R but they're too stiff on the rear.
I've now put on the M235i bars now and they're too weak on the front.
The sweet spot is probably the KW or Eibach, which I might try next.
(I always put bars in pairs because they're designed as pairs)

Some vendors (Hotchkis, Dinan) have hollow bars so you can't directly compare diameters with plain, non-hollow bars, hollow bar will be weaker than plain for same outer diameter.

Hope this helps...
Attached Images
 
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 4
      09-01-2017, 11:33 AM   #2
JamesNoBrakes
Lieutenant Colonel
815
Rep
1,706
Posts

Drives: 428i xdrive GC
Join Date: May 2015
Location: Alaska

iTrader: (0)

Quote:
Originally Posted by Lancelot View Post
I've put together a table of the available ARBs for our platform, BMW has quite a lot of options depending on engine, suspension, M Sport, M Adaptive or standard.

In a nutshell:
- 6 cyl get weaker front bars than 4 cyl engines
- M Sport has slightly stronger bars front and rear
- 440i LCI have stronger bars (same as M235i) than non-LCI 435i
- Xdrive have weaker front bars but same rear bars.

Aftermarket:
I've tried the H&R but they're too stiff on the rear.
I've now put on the M235i bars now and they're too weak on the front.
The sweet spot is probably the KW or Eibach, which I might try next.
(I always put bars in pairs because they're designed as pairs)

Some vendors (Hotchkis, Dinan) have hollow bars so you can't directly compare diameters with plain, non-hollow bars, hollow bar will be weaker than plain for same outer diameter.

Hope this helps...
While that is true, a slight increase in the size of a hollow cylinder results in a much stronger structure than the solid. 1" vs 1.125 hollow, the hollow was something like 128% stronger at 70% of the weight. Also, with the way circles work, a few more mm in diameter with a hollow structure may not be as light as you are thinking. There's a dramatic increase in circumference.
Appreciate 0
      09-01-2017, 12:21 PM   #3
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Indeed, for those who are more math inclined the stiffness is calculated as a proportional to (D^4 - d^4) where D = outer diameter and d = inner diameter (and d = 0 if the bar is plain), while the weight is proportional to (D^2 - d^2).
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 0
      09-05-2017, 03:16 PM   #4
DSH7
Private First Class
17
Rep
124
Posts

Drives: F30 328i
Join Date: Aug 2016
Location: Pacific Northwest

iTrader: (0)

Interesting thread. So any idea which is stiffest? I would assume it's between H&R (28,20mm solid) versus AFE (32,29mm hollow).
Appreciate 0
      09-06-2017, 02:41 AM   #5
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Quote:
Originally Posted by DSH7 View Post
Interesting thread. So any idea which is stiffest? I would assume it's between H&R (28,20mm solid) versus AFE (32,29mm hollow).
To be able to answer the question there is one last parameter: the lever arm length. Basically if the arm is shorter the bar is made stiffer.

And to make it a little more complex, most aftermarket parts are adjustable at the front, sometimes at the back like Dinan.

I'll try to update this table with the info I can find on this to try to paint the full picture.

Data I have for the 6 cylinders:
- KW and Eibach have front lever arm lengths 250 and 270mm (two way adjustable each side = 3 possible settings - Short/Short, Short/Long, Long/Long)
- H&R have lever arm lengths 250 and 265mm for the 6 cylinder version

All 3 are 150mm at the back.
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 0
      09-06-2017, 06:54 PM   #6
Maxwagen
Private
10
Rep
97
Posts

Drives: 2017 330i Wagon
Join Date: Jul 2017
Location: Trumbull, CT

iTrader: (0)

Is it difficult to put a front bar on these cars? (Xdrive). I know in my Mini Cooper, it would involve dropping entire front subframe.
__________________
2017 330i Wagon | Glacier Silver/Black/Anthracite, M-sport, Nav, Tech, Premium, DA, DA+, Cold, LED's, Carplay
Appreciate 0
      09-07-2017, 08:13 AM   #7
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Yes BMW has adopted the same architecture on the F2x/F3x subframes, so quite a pain indeed, although my shop has done that quicker last time, altogether I was there for 5 hours for 2 anti-roll bars, rear subframe bushings, intercooler and downpipe.
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 0
      09-07-2017, 09:20 PM   #8
Maxwagen
Private
10
Rep
97
Posts

Drives: 2017 330i Wagon
Join Date: Jul 2017
Location: Trumbull, CT

iTrader: (0)

I just got my car on Tuesday (2017 f31) and am on the lookout for whatever the consensus is on a good anti roll bar setup to tame the xdrive body roll. Coming from a Mini and then a Focus ST, it was actually kind of alarming..
__________________
2017 330i Wagon | Glacier Silver/Black/Anthracite, M-sport, Nav, Tech, Premium, DA, DA+, Cold, LED's, Carplay
Appreciate 0
      09-08-2017, 03:23 AM   #9
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

The difficulty with bars is finding the right balance between taming roll and keeping suspension independence: with bars that are too stiff, potholes and similar bumps will upset the entire car balance, instead of leaving the single wheel / damper absorb the shock, it will be transmitted to the entire body.

Springs and coilovers do not have the same inconvenience so it's a better place to start in my opinion, and if not enough then use bars as a stage 2.
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 1
Polo088161092.50

      09-08-2017, 08:25 AM   #10
Insane435
Captain
Insane435's Avatar
United_States
203
Rep
835
Posts

Drives: 435ix M Sport EWG
Join Date: Jul 2016
Location: Michigan

iTrader: (1)

do you have to drop the exhaust to install front an rear ARBs on an xdrive? (435)
__________________
2014 EBII 435ix - Armytrix Catback, Evolution Racewerks Downpipe - Chargepipe - Intercooler, Bootmod3, NGK 97506's, AFE Dry Filter, KW V1, Forgestar F14 19s, Potenza S-04's, M Performance Brakes, M Power Pads
2011 BSM 328ix
IG: @f32_rmacher
Appreciate 0
      09-08-2017, 08:45 AM   #11
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Quote:
Originally Posted by Insane435 View Post
do you have to drop the exhaust to install front an rear ARBs on an xdrive? (435)
Yes for the rear but that takes literally 5 minutes.
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 0
      09-08-2017, 09:37 AM   #12
Insane435
Captain
Insane435's Avatar
United_States
203
Rep
835
Posts

Drives: 435ix M Sport EWG
Join Date: Jul 2016
Location: Michigan

iTrader: (1)

Quote:
Originally Posted by Lancelot View Post
Yes for the rear but that takes literally 5 minutes.
5 mins for normal people, my exhaust barely fits (xdrive problems) I cant imagine how much work i would be adding to realign the whole damn thing.
__________________
2014 EBII 435ix - Armytrix Catback, Evolution Racewerks Downpipe - Chargepipe - Intercooler, Bootmod3, NGK 97506's, AFE Dry Filter, KW V1, Forgestar F14 19s, Potenza S-04's, M Performance Brakes, M Power Pads
2011 BSM 328ix
IG: @f32_rmacher
Appreciate 0
      09-08-2017, 10:04 AM   #13
Polo08816
Brigadier General
1093
Rep
3,099
Posts

Drives: 2014 335i M Sport
Join Date: Sep 2010
Location: MD

iTrader: (0)

Quote:
Originally Posted by Insane435 View Post
do you have to drop the exhaust to install front an rear ARBs on an xdrive? (435)
Quote:
Originally Posted by Lancelot View Post
Yes for the rear but that takes literally 5 minutes.
Dropping the subframe is the most challenging part. That takes a bit of time.
Appreciate 0
      09-19-2017, 09:18 AM   #14
AshlandTE87
Private
16
Rep
95
Posts

Drives: 2015 335i M-Sport 6sp
Join Date: Nov 2015
Location: Your mom's house

iTrader: (0)

Is there a good DIY out there for dropping the rear subframe?
Appreciate 0
      09-19-2017, 09:44 AM   #15
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Quote:
Originally Posted by AshlandTE87 View Post
Is there a good DIY out there for dropping the rear subframe?
I found the Dinan install guide for their anti roll bars to be good
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 1
      09-29-2017, 02:37 PM   #16
Niart906
Second Lieutenant
131
Rep
253
Posts

Drives: 2013 335i M-Sport 6spd
Join Date: Feb 2015
Location: Scranton, PA

iTrader: (0)

Quote:
Originally Posted by Lancelot View Post
I found the Dinan install guide for their anti roll bars to be good
I'll second this, just installed a set of Megan Racing sway bars on my 335. The Dinan instructions are excellent, but make no mistake the install is a huge pain in the ass. The rear is relatively easy, but maneuvering the front bar into place took some time.
__________________

2013 335i Estoril Blau II/Black
6spd | M-Sport | JB4+BEF | BMS Intake | ER D-P | VRSF Chargepipe | Phoenix FMIC | Megan Racing Sway Bars | H&R Sport Springs
Appreciate 0
      09-30-2017, 08:45 AM   #17
Polo08816
Brigadier General
1093
Rep
3,099
Posts

Drives: 2014 335i M Sport
Join Date: Sep 2010
Location: MD

iTrader: (0)

Quote:
Originally Posted by Niart906 View Post
I'll second this, just installed a set of Megan Racing sway bars on my 335. The Dinan instructions are excellent, but make no mistake the install is a huge pain in the ass. The rear is relatively easy, but maneuvering the front bar into place took some time.
You had access to a lift and transmission/diff jack right?
Appreciate 0
      09-30-2017, 09:47 AM   #18
Orion4
Major
United_States
244
Rep
1,102
Posts

Drives: 2013 335i Sport Line Sedan
Join Date: Aug 2009
Location: Melbourne, FL

iTrader: (0)

Doesn't the type and condition of the swaybar bushings have some degree of impact on the bar performance (i.e. Rubber vs polyurethane, etc)?
Appreciate 0
      10-02-2017, 11:46 AM   #19
AshlandTE87
Private
16
Rep
95
Posts

Drives: 2015 335i M-Sport 6sp
Join Date: Nov 2015
Location: Your mom's house

iTrader: (0)

Quote:
Originally Posted by Lancelot View Post
I found the Dinan install guide for their anti roll bars to be good
Thanks! Yeah, it does look pretty comprehensive upon review.
Appreciate 0
      10-12-2017, 02:41 PM   #20
dotjonnL
Private First Class
Canada
16
Rep
153
Posts

Drives: 335iX M-Performance
Join Date: May 2015
Location: Victoria//Vancouver

iTrader: (0)

Trying to figure out which ARBs to put on my xdrive, you think the 440i LCI bars would work/help with body roll?
Appreciate 0
      10-12-2017, 11:31 PM   #21
Lancelot
Major
France
348
Rep
1,046
Posts

Drives: 2014 M Sport ActiveHybrid3
Join Date: Sep 2012
Location: France

iTrader: (0)

Yes or m135i/m140i ; probably best to start with springs or coilovers.
__________________
2014 M Sport ActiveHybrid 3
M Performance BBK - F80 CFRP struts brace - Quaife LSD - KW DDC coilovers - Akrapovic Exhaust - HJS EU6 downpipe - Wagner Evo2 Comp IC - BMC air filter - Powerflex Black Subframe Bushings - Bimmertech amp with Focal speakers
Appreciate 0
      10-12-2017, 11:57 PM   #22
dotjonnL
Private First Class
Canada
16
Rep
153
Posts

Drives: 335iX M-Performance
Join Date: May 2015
Location: Victoria//Vancouver

iTrader: (0)

Already have Dinan springs and shockware, body roll still there.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 03:24 PM.




f30post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST