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      01-15-2015, 07:20 PM   #1
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F8x M3/M4 Front Lower Control Arm Upgrade for 2-Series

Update:
Because of all the uncertainties and concern surrounding the effect on the steering by just using the lower control arms, we are going to order up a full set of F8x front suspension arms for our 228i to figure out what specifically is needed to run the tension struts as well. Hopefully we will just be looking at some spacers for the front bushings. That way, the steering geometry will be as designed and everybody can upgrade with confidence. I'll let you guys know as soon as they come in and I'll document the findings.




As anyone who is interested in improving the handling of their vehicle has no doubt discovered, BMW’s new F generation of cars, which includes the new F22 2-Series and the F30 3-Series, do not have adjustable front camber. Unlike previous generations, the design of the tophat does not allow for easy adjustment and the lower arm is fixed, without utilizing an alignment bolt. Unfortunately, this puts the stock, factory camber at about 0.4-0.5 degrees. This is less than ideal for spirited street driving and severely compromised for any type of track activities.

As some members here on the forum had hypothesized, just like in previous generations, the M car suspension pieces are similar in design and fitment to the standard cars but longer to extend the track width of the vehicle.

Here is the camber measurement with the stock 228i front lower control arm with a reading of 3.2 degrees. Ignore the high number as we have KW motorsport coilovers fitted on the car with adjustable top hats and an aggressive camber setting for track use. We will be looking at the difference in camber when we switch to the F8x FLCA.





Here is the stock 228i front suspension compared to that of the M4. The design and layout is very similar but the M4 links are longer to increase the track width and the components are generally beefed up to hold up to the abuse that an M car is destined to see.






Here are the links out of the cars. You can see the design is very similar, but the F8x part is reinforced and uses a spherical bearing inboard to improve the steering responsiveness. The M4 arm is slightly longer, approximately 10mm, which is what we are looking for to increase the front camber.



Important Note: In the comparison you can [SIZE="2"]also see the stock 228i arm is shaped for increased inner wheel clearance under full compression for smaller diameter, high offset wheels. Unfortunately we did not have the stock 17” wheels handy to test for interference. While it seems like should be enough clearance for the 17” wheels we would strongly recommend running larger 18” diameter wheels that the M3/M4 are designed for if switching to these control arms. Failure to do so could result in contact between the inner barrel and lower control arm which could cause front suspension and or wheel failure. GSR Autosport is not responsible for any issues or damage caused by this modification and it is your responsibility to check for interference issues.

One observation, the kingpin from the outer balljoint on the 228i is slightly longer by about 2mm but swapping to the M4 arm with the slightly shorter kingpin does not create any fit issues.



Here is the M4 arm installed on the 228i. As you can see, it is basically a straight swap. Everything fits just like the stock piece and it goes together the same way as it came apart.





Here is the shot of the new camber measurement with the M4 FLCAs installed. That is 4.5 degrees, a 1.3 degree increase from stock.





On a stock car this should put front camber at about 1.6-1.8 degrees which is perfect for a performance street car alignment or a multi-purpose car that sees occasional track use.

While all these measurements were taken from an F22 2-Series, it should provide a similar improvement in front camber on F30 3-Series cars as well.

The M3/M4 Front Lower control arms retail for $184.71 each from the dealer, with the following part numbers:
Left: 31-12-2-284-529
Right: 31-12-2-284-530

To make the upgrade as painless as possible, we have the arms available as a kit on our webstore, available here

Last edited by GSR Technik; 01-23-2015 at 07:37 PM..
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      01-16-2015, 03:57 AM   #2
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Great stuff.

How do the stock xenon headlights regulator rods connect to the m3/4 LCA ?

Are the F8x tension struts not necessary ?

Do LCA's mean changing regulator rod for xenon headlight levelling ?

What alignment specs in terms to toe-in etc did you change before/after install of LCA's ?

Thanks,

BP
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Last edited by Bee Pee; 01-16-2015 at 02:59 PM..
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      01-16-2015, 03:06 PM   #3
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The Thrust arms do not appear to be a straight swap. From my rough measurements, the front bushing is a fair bit wider on the 228i and appears to be a slightly different diameter, so you can’t just press the 228i bushings in the F8x thrust arms. This could probably be solved with some spacers on each side of the bushing. This is something we may look into further in the future.

However, it seems to be a small enough change in length to just the lower control arm that it shouldn't require the tension struts to be changed. It obviously fits just fine with just the lower control arms installed and the wheel stays located in the middle of the wheelwell. While it theoretically will have a slight effect on caster and upright pivot point, it is such a small amount that it shouldn't have any negative effects. When we put the car on the ground, steering effort and feel was similar to stock but that is hard to judge with the electric steering. We have not had a chance to test these out on the track yet but will do a full report when we do.

Regarding the Headlight leveling sensor, unfortunately our 228i is a base model and does not utilize the headlight leveling sensors. Presumably, it would just require the shorter regulating rod from the M3/M4. You can see the different designs here:
2-Series: http://realoem.com/bmw/showparts.do?...48&hg=31&fg=05
M3/M4:http://realoem.com/bmw/showparts.do?...26&hg=31&fg=05

The part number for the F8x regulating rod is 37-14-2-283-867.

Also, you'll definitely need to correct the toe with an alignment after installing these arms.
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      01-20-2015, 01:05 AM   #4
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Wow, great stuff GSR!
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      01-20-2015, 09:38 AM   #5
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I'll grab it next week who can say no to more negative camber??
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      01-20-2015, 05:29 PM   #6
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M-terkait - does you 335i have xenons ? If so you will need connecting rod for hradlight self levelling feature. Keen to know how you get on. BP
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      01-22-2015, 12:42 AM   #7
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Quote:
Originally Posted by Bee Pee View Post
M-terkait - does you 335i have xenons ? If so you will need connecting rod for hradlight self levelling feature. Keen to know how you get on. BP
yes of course not halogens, okay I'll report when i get the part.
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      01-22-2015, 03:09 AM   #8
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Quote:
Originally Posted by GSR Autosport View Post
The Thrust arms do not appear to be a straight swap. From my rough measurements, the front bushing is a fair bit wider on the 228i and appears to be a slightly different diameter, so you can’t just press the 228i bushings in the F8x thrust arms. This could probably be solved with some spacers on each side of the bushing. This is something we may look into further in the future.

However, it seems to be a small enough change in length to just the lower control arm that it shouldn't require the tension struts to be changed. It obviously fits just fine with just the lower control arms installed and the wheel stays located in the middle of the wheelwell. While it theoretically will have a slight effect on caster and upright pivot point, it is such a small amount that it shouldn't have any negative effects. When we put the car on the ground, steering effort and feel was similar to stock but that is hard to judge with the electric steering. We have not had a chance to test these out on the track yet but will do a full report when we do.

Regarding the Headlight leveling sensor, unfortunately our 228i is a base model and does not utilize the headlight leveling sensors. Presumably, it would just require the shorter regulating rod from the M3/M4. You can see the different designs here:
2-Series: http://realoem.com/bmw/showparts.do?...48&hg=31&fg=05
M3/M4:http://realoem.com/bmw/showparts.do?...26&hg=31&fg=05

The part number for the F8x regulating rod is 37-14-2-283-867.

Also, you'll definitely need to correct the toe with an alignment after installing these arms.
If F8x TS are different, begs the question if E9x M3 LCA and TS fit and would have the desired effect of more -ve camber???? I did this mod on my e91 335i touring, tightened up the front end nicely.

It makes sense to me to upgrade both LCA and TS and I have past positive experience. I'm keen to read outcome of how just F8x LCA upgrade works in practice.
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      01-23-2015, 07:06 AM   #9
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Quote:
Originally Posted by GSR Autosport View Post
The Thrust arms do not appear to be a straight swap. From my rough measurements, the front bushing is a fair bit wider on the 228i and appears to be a slightly different diameter, so you can’t just press the 228i bushings in the F8x thrust arms. This could probably be solved with some spacers on each side of the bushing. This is something we may look into further in the future.

However, it seems to be a small enough change in length to just the lower control arm that it shouldn't require the tension struts to be changed. It obviously fits just fine with just the lower control arms installed and the wheel stays located in the middle of the wheelwell. While it theoretically will have a slight effect on caster and upright pivot point, it is such a small amount that it shouldn't have any negative effects. When we put the car on the ground, steering effort and feel was similar to stock but that is hard to judge with the electric steering. We have not had a chance to test these out on the track yet but will do a full report when we do.

Regarding the Headlight leveling sensor, unfortunately our 228i is a base model and does not utilize the headlight leveling sensors. Presumably, it would just require the shorter regulating rod from the M3/M4. You can see the different designs here:
2-Series: http://realoem.com/bmw/showparts.do?...48&hg=31&fg=05
M3/M4:http://realoem.com/bmw/showparts.do?...26&hg=31&fg=05

The part number for the F8x regulating rod is 37-14-2-283-867.

Also, you'll definitely need to correct the toe with an alignment after installing these arms.
I'm interested but keener on changing out both LCA and TS as opposed to just LCA so, apart from more camber, the axle/steering geometry remains as-is. LCA's only with stock TS will effect castor angle.

It would be interesting [and cheaper in terms of parts cost] to know if e9x M3 LCA and TS would work on Fxx series cars.....
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      01-23-2015, 07:36 PM   #10
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Because of all the uncertainties and concern surrounding the effect on the steering by just using the lower control arms, we are going to order up a full set of F8x front suspension arms for our 228i to figure out what specifically is needed to run the tension struts as well. Hopefully we will just be looking at some spacers for the front bushings. That way, the steering geometry will be as designed and everybody can upgrade with confidence. I'll let you guys know as soon as they come in and I'll document the findings.
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      01-24-2015, 02:00 AM   #11
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Great. Thanks, subscribed !
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      01-28-2015, 09:14 AM   #12
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will it fits a 335 xdrive?
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      02-04-2015, 07:57 PM   #13
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Just a quick update. We are waiting on the Tension Struts which are out of stock in the US and are coming from Germany. I'll post up when they come in and we can get them on the car.

Yuqi-
I do not know. Unfortunately we don't have an xdrive car here or know of one locally to test them on.
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      02-05-2015, 03:10 PM   #14
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Looking forward to more updates. Great work!!!
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      02-05-2015, 09:51 PM   #15
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Installed the F8x LCA's on my 228i tonight. Holy toe in after install! Also installed 12.5mm spacers up front and 15mm in the rear. So far, so good. Interested to learn more on the tension struts as well.
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      02-06-2015, 01:16 AM   #16
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You need an alignment, ASAP. Not safe to drive around like that
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      02-06-2015, 02:19 AM   #17
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Quote:
Originally Posted by i8ur911 View Post
Installed the F8x LCA's on my 228i tonight. Holy toe in after install! Also installed 12.5mm spacers up front and 15mm in the rear. So far, so good. Interested to learn more on the tension struts as well.
Does your 228i have xenons and if so what's the part number of the regulator rod [connects to LCA] did you use ?

Once you get the alignment tweaked, be interested in getting your feedback on how it drives + photos of the front camber post install.

Enjoy !
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      02-06-2015, 09:36 PM   #18
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My car doesn't have xenons. I ordered the car with one thing in mind....the track (track pkg and MSport).

Alignment is good. The car gains 1* of camber with the F8x arms.

Initial review is, the car feels great. The F2x chassis desperately needs negative camber.

I'll be adding H&R springs next. 12.5mm and 15mm spacers are pretty much the max on the stock wheels (the plastic "dust cap" needs to be removed for spacers to sit flush against rotor).
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      02-08-2015, 10:08 PM   #19
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any updates?
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      02-09-2015, 03:01 AM   #20
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Quote:
Originally Posted by i8ur911 View Post
My car doesn't have xenons. I ordered the car with one thing in mind....the track (track pkg and MSport).

Alignment is good. The car gains 1* of camber with the F8x arms.

Initial review is, the car feels great. The F2x chassis desperately needs negative camber.

I'll be adding H&R springs next. 12.5mm and 15mm spacers are pretty much the max on the stock wheels (the plastic "dust cap" needs to be removed for spacers to sit flush against rotor).
Thanks for the feedback. It would be great to see some photos of your 228i post install.
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      02-16-2015, 02:12 AM   #21
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Subscribed.

Any updates Guys?
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      02-17-2015, 03:32 AM   #22
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I would have one remark: 228i and M235i don't have the same FLCAs!

M135i and M235i have different BMW FLCAs references from other F2x and F3x:

- M135i/M235i:
L: 31 10 6 857 329
R: 31 10 6 857 330


- 228i and other F2x and F3x:
L: 31 12 6 852 991
R: 31 12 6 852 992


So did you cross check also on a M235i to be sure that all is OK and what is the difference between M235i FLCAs and 228i ones?
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