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      06-14-2017, 03:35 AM   #1
Dmitry83
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N20 Anti roll bars upgrade

Hi, All,


At first my F30 had a standard suspension, which was upgraded to M-Technik springs and corresponding Koni Sport shocks.
Now only the anti roll bars left untouched- those are 24mm front and 12mm rear.

So I'm looking in four options:

1) Simple M-Technik ARB upgrade- 24,2mm and 13mm
2) Front M-Technik 25,2/22,2mm M135i (could be progressive?), rear M135i 15mm
3) Only M135i rear 15mm (is there any difference in bushings stiffnes of base 24mm and M-Technik 24,2mm front to mess with 0,2mm?)
4) Only M-Technik rear 13mm- no mess with front one replacement, closest to the factory M-Technik suspension setup.

Tire setup is 225/255 staggered on 400M wheels and the steering is neutral, which I would like to warm up a bit with no harsh ride, so H&R are not what I should look to.

Interesting is that F32 420i has 13mm rear in base, 14mm in M-Technik (front is tge same 24mm and 24,2mm correspondingly). Whereas in F32LCI they went to 25mm front and 15mm only.

What you think would be the most sufficient?
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Last edited by Dmitry83; 06-14-2017 at 06:56 AM..
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      06-14-2017, 10:25 AM   #2
Lancelot
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Hi, i think it's difficult to answer without knowing what you want to change with the car behaviour, to which extent.

FWIW i'm reverting from H&R to F32 LCI ARBs, having learned my lesson the hard way, I'll be able to report my impressions in a couple of weeks when the new setup is on.
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      06-14-2017, 11:56 AM   #3
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Quote:
Originally Posted by Lancelot View Post
Hi, i think it's difficult to answer without knowing what you want to change with the car behaviour, to which extent.

FWIW i'm reverting from H&R to F32 LCI ARBs, having learned my lesson the hard way, I'll be able to report my impressions in a couple of weeks when the new setup is on.
Hi, Man,

At the moment I have the totally neutral steering and a little roll. Would like to add some oversteering plus flattering ovarally a bit.
The reason why I'm still looking to increasing the front one (not only rear)- this should improve the initial steering response and eliminate body roll. With no harsh ride for sure- so no H&R or Eibach kits are considered.
Also I have good experience with E93 M3 28mm front ARB instead of 26,5mm on my former E81 120i- it surprisingly eliminated(!) understeering, steering response became razor-sharp. Rear ARB was unchanged 12mm then.

The difficulty of decision is I don't have the experience of full M-Technic suspension with 24,2mm front & 13mm rear ARBs. Maybe it is completely perfect with no effect on ride quality. And I have an offer for the rear used one for $70 only.

However the F32 LCI you mentioned has 25mm front and 15mm rear in M-Technik (S704A) package. Do you mean this combo?
Remembering the 4-er is more appreciated in the reviews for steering character, I would go for the same or for complete M135i set of ARBs with 25,2/22,2mm front and 15mm rear.
Just don't know how does this variable thickness work- some kind of progressiveness maybe?
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'13 F30 320i (328i ECU) RWD M-Sport
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F80 bottom reinforcement plate
Koni Sport, M-Performance springs, M135i Anti-roll bars

Last edited by Dmitry83; 06-14-2017 at 12:23 PM..
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      06-14-2017, 12:36 PM   #4
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F32 LCI and M135i/M235i are the same parts, 25,2/22,2 front & 15mm rear.
Not sure if it's variable thickness or what, original parts were 25/21,2 and didn't look progressive, perhaps it's the center vs. side thickness.

Anyhow, all I can say is I loved my F20 M135i when I had one, so I expect the same bars will probably give a good balance, being thicker than stock but not as stiff as H&R at the back (what a pain! what were they thinking!)
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      06-14-2017, 12:56 PM   #5
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Quote:
Originally Posted by Lancelot View Post
F32 LCI and M135i/M235i are the same parts, 25,2/22,2 front & 15mm rear.
Not sure if it's variable thickness or what, original parts were 25/21,2 and didn't look progressive, perhaps it's the center vs. side thickness.

Anyhow, all I can say is I loved my F20 M135i when I had one, so I expect the same bars will probably give a good balance, being thicker than stock but not as stiff as H&R at the back (what a pain! what were they thinking!)
That's what is exactly what I'm looking for.
And yes- the center segment should be 22,2mm and the sides are 25,2mm.

However the front F20 M135i and F32 440i partnumber is 31 35 6 792 120 and 25,2/22,2, whereas the F32 420i is 31 35 6 792 113 and 25mm. Strange.
So maybe for lighter engine- stiffer front as the springs/dampers are softer?

Very interested in your experience!
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'13 F30 320i (328i ECU) RWD M-Sport
Michelin PSS, M-Sport brakes, 320i LCI muffler
F32 bottom V-bar
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      06-14-2017, 05:34 PM   #6
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Quote:
Originally Posted by Lancelot View Post
Hi, i think it's difficult to answer without knowing what you want to change with the car behaviour, to which extent.

FWIW i'm reverting from H&R to F32 LCI ARBs, having learned my lesson the hard way, I'll be able to report my impressions in a couple of weeks when the new setup is on.
I'm waiting for your impressions before I pull the trigger on the LCI ARBs as my xdrive feels sloppy even with Dinan springs and shockware.
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      06-15-2017, 06:02 AM   #7
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Quote:
Originally Posted by Lancelot View Post
F32 LCI and M135i/M235i are the same parts, 25,2/22,2 front & 15mm rear.
Not sure if it's variable thickness or what, original parts were 25/21,2 and didn't look progressive, perhaps it's the center vs. side thickness.

Anyhow, all I can say is I loved my F20 M135i when I had one, so I expect the same bars will probably give a good balance, being thicker than stock but not as stiff as H&R at the back (what a pain! what were they thinking!)
Had just ordered the M135i set:
31 35 6 792 120 (25.2/22.2mm front ARB)
33 55 6 853 476 (15mm rear ARB)
33 50 6 792 199 (rear ARB bushings, 2pcs)
The brackets and the ARB struts are equal so do not need replacement.
Alltogether- around EUR 315.

The installation together with alignment will cost me just EUR 80, so not that expensive EUR 400 mod, that should bring the good grip and steering response improvement.

So thank you for your recommendations- hope this set will work well with the M-Technik springs and Koni Sport shocks I have!
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Koni Sport, M-Performance springs, M135i Anti-roll bars

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      06-16-2017, 01:33 PM   #8
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Any reason why you went with the 440I Front 25mm vs the 420I front 25mm bar?

Also from doing AutoX with different cars I noticed that a lot of cars actually get a sharper turn in rate with the front bar upgrade only. But report back and possible do a DIY as I am gathering info for this upgrade myself. THinking of going with a 28mm front bar and the 15mm rear if I don't already have it in my Sport equipped package.

Last edited by D041987; 06-19-2017 at 01:38 PM..
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      06-19-2017, 06:40 AM   #9
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Quote:
Originally Posted by D041987 View Post
Any reason why you went with the 440I Front 25mm vs the 420I front 25mm bar?

Also from doing AutoX with different cars I noticed that a lot of cars actually get a sharper turn in rate with the rear bar upgrade only. the 1mm difference from stock might not make as a drastic difference as the rear upgrade will. But report back and possible do a DIY as I am gathering info for this upgrade myself.
Actually I've chosen front+rear M135i complete set, which is equal to 440i at the front only by the measurements, but the partnumbers are different (21 35 6 792 120 for M135i and 31 35 6 792 119 for 440i), so I suppose the length of 22,2mm segment is less for M135i.

And the rear M135i partnumber 33 55 6 853 476 is equal to 420i at the rear (M-Technik) and is 15mm which is not offered to 440i at all (13mm for 440i M-Technik).

So all in all I expect to get a good balance with a pronounced oversteering under acceleration, but not dangerous or ruining the handling and overall grip.
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Michelin PSS, M-Sport brakes, 320i LCI muffler
F32 bottom V-bar
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Koni Sport, M-Performance springs, M135i Anti-roll bars

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      06-19-2017, 01:32 PM   #10
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Nice, I got confused at the two numbers 25.2 and 22.2. But makes sense now since the 4 series is wider. I have the sport suspension already but need to measure the bars as I think I am already at a 25mm bar in front and 14 in the rear on the 328i according to some other sources that I have looked at but if not I might look into upgrading the front bar only and seeing how it acts before I tackle the rear bar as you have to drop the subframe ;-(
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      06-19-2017, 01:35 PM   #11
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I don't agree there is a difference btw F2x and F3x series, when you check the parts on realoem.com the same parts apply to 440i LCI and M135i.

Also you'll need to drop front subframe too, not just rear, unlike E9x chassis.
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      06-19-2017, 02:38 PM   #12
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Quote:
Originally Posted by D041987 View Post
Nice, I got confused at the two numbers 25.2 and 22.2. But makes sense now since the 4 series is wider. I have the sport suspension already but need to measure the bars as I think I am already at a 25mm bar in front and 14 in the rear on the 328i according to some other sources that I have looked at but if not I might look into upgrading the front bar only and seeing how it acts before I tackle the rear bar as you have to drop the subframe ;-(
Those two numbers could mean the front bar is 25.2mm at the ends and 22.2mm segment in the middle. This narrow segment looks around 30cm long.

328i has sll the same as 320i does:
Front- 24mm standard, 24,2mm M-Technik
Rear- 12mm standard, 13mm M-Technik

To replace the front bar on F30 you wil have to drop the front subframe, as the ARB is mounted on top of it- same as the rear one. On E90 it was mounted under the subframe.
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      06-20-2017, 03:05 PM   #13
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Quote:
Originally Posted by Lancelot View Post
F32 LCI and M135i/M235i are the same parts, 25,2/22,2 front & 15mm rear.
Not sure if it's variable thickness or what, original parts were 25/21,2 and didn't look progressive, perhaps it's the center vs. side thickness.

Anyhow, all I can say is I loved my F20 M135i when I had one, so I expect the same bars will probably give a good balance, being thicker than stock but not as stiff as H&R at the back (what a pain! what were they thinking!)
But what I did not think well before- is the shape of M135i bar is different to 320i as the 6-cylinder engine has another power-steering motor placement and the engine itself.

Probably it would be better to change the order for 24,2mm M-Technik (31 35 6 792 125) front one for pre-LCI 320i with N20 engine.
But referring to Dinan DNN018 front+rear kit, which is applicable to all models from 320i to 335i, the M135i kit should fit F30 320i, as the suframes are the same on M135i and 320i.

So seems I'll be the first to try installing M135i bars on F30 with N20 engine.)
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      06-21-2017, 07:34 AM   #14
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Quote:
Originally Posted by Dmitry83 View Post
Actually I've chosen front+rear M135i complete set, which is equal to 440i at the front only by the measurements, but the partnumbers are different (21 35 6 792 120 for M135i and 31 35 6 792 119 for 440i), so I suppose the length of 22,2mm segment is less for M135i.

And the rear M135i partnumber 33 55 6 853 476 is equal to 420i at the rear (M-Technik) and is 15mm which is not offered to 440i at all (13mm for 440i M-Technik).

So all in all I expect to get a good balance with a pronounced oversteering under acceleration, but not dangerous or ruining the handling and overall grip.
Where do you see these differing part numbers? looking them up on realoem.com I see the same part numbers for both.
Considering F2x and F3x have identical subframes (at least as far as I know) that would make sense to have identical ARBs.
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      06-21-2017, 08:04 AM   #15
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Quote:
Originally Posted by Lancelot View Post
Where do you see these differing part numbers? looking them up on realoem.com I see the same part numbers for both.
Considering F2x and F3x have identical subframes (at least as far as I know) that would make sense to have identical ARBs.
I use the elcats.ru/bmw, as it is on Russian and is available for regular users.
There I can see all versions of parts applicable for example to standard, M-Technik and M-Adaptive in one table simultaneously.
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      08-21-2017, 05:03 AM   #16
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So yesterday the 25,2/22,2mm front & 15mm rear M135i/M235i anti-roll bars had been successfully installed- seems first in the World experience on N20.

Difference in the shape turned out to be for the coolant tubes clearance only. The N55 front ARB simply needs more space for the peripherial engine parts.

By now I need some 200-300km highway load to make the springs return to their nominal compression after the car was hanging overnight. But anyway, the change in roll control is really dramatical.
Overall mechanical grip is increased.
Also the rear suspension starts to work much faster after the steering inputs.

Overall turning balance seems unchanged even with no additional rebound adjustments to the Koni Sports (being set on 200 degrees front & 180 degrees rear with stock ARBs). Will wait for the springs to settle back completely and wach how it all will behave.

Will try to get out of the city tonight to have some highway run for some detailed update.
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