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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Non-M and M front tension arm (not bush) difference (if any)?



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      06-10-2014, 05:17 AM   #1
bradsm87
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Non-M and M front tension arm (not bush) difference (if any)?

Hi,

I've seen various comparison pics of E8x/E9x M vs non-M front tension arms (aka upper control arms) and can't see any difference other than the bushes. Turner Motorsports's site says that the M3 bushes alone are an upgrade for non-M cars, meaning that they can be fitted to the non-M arms. Also the same BMW Motorsport bush lists compatability for both M and non-M models, further confirming the cross-compatibility of the bushes. I understand that the part numbers for the arms are different but is it only because they are only available to buy with bushes fitted and obviously the bushes are different?

I can't seem to see a difference in length on comparison pics but IF the non-M arms are a touch shorter but can take the M bushes, then I see that as THE best option as it'll increase caster when used with M lower control arms.

TRW M3 tension arm bushes are $20.30 each at ecstuning. That along with a decent shipping saving to AUS for me looks like the way to go!

Who has seen both items together and can confirm any differences?

Cheers,

Brad

Last edited by bradsm87; 06-10-2014 at 05:23 AM.
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      06-11-2014, 05:55 PM   #2
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Surely someone has upgraded to M3 arms and done a good visual comparison between the two?
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      06-11-2014, 07:44 PM   #3
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I did the mod two months ago and upon visual inspection, the M tension arms are in fact shorter in length by maybe an inch than the stock tension arms. There also seems to be some difference in the clearance angle near the center of the arm. I have photos if you really really need them.
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      06-11-2014, 07:59 PM   #4
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Photos would be great as all photos I've found on the net show the length to be extremely similar and any perceived difference in length in the pics looked to be because of the angle that the photo is taken from, the angle of the ball joint or the arms not being lined up together properly.

Also can anyone confirm by measuring that the outer shells on the bushes are the exact same outer diameter (or the inner diameter of the alloy bore)?
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      06-12-2014, 04:44 PM   #5
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I don't think only the bushing creates a better steering response in which the stock control arms are made of sheet metal thus a greater chance of flexing. While the m3 arms are made of one piece aluminum.
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      06-12-2014, 05:23 PM   #6
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Quote:
Originally Posted by mikex25 View Post
I don't think only the bushing creates a better steering response in which the stock control arms are made of sheet metal thus a greater chance of flexing. While the m3 arms are made of one piece aluminum.
That's the case for the rears but not the fronts.

These are the arms in question (courtesy of robc1976 on BB forum)

[IMG]http://www.german**********/images/imported/2013/02/step12m-1.jpg[/IMG]

Edit: e90post have obviously listed g e r m a n b o o s t as a 'sware word' and will not display the pic. Just replace the stars with '**********'.
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      06-13-2014, 11:55 AM   #7
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I have two photos of the arms lined up for difference. I will post them when I can. When you have one M arm on and a stock arm on the other you will see a noticeable difference in toe.
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      06-21-2014, 04:34 AM   #8
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Still very interested to see some hard evidence on this one. Preferably measurements or at least a photo of both arms with the photo taken nice and square indicating the difference.
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      06-21-2014, 07:10 PM   #9
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Scroll through the pics. The difference is fairly obvious between the two. http://www.e90post.com/forums/showth...3+control+arms
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      06-21-2014, 10:33 PM   #10
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The comparison photo there doesn't have them lined up properly so it's impossible to judge.
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      06-21-2014, 11:19 PM   #11
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Dude, I'm telling you there's a difference. I have both in my garage. I don't have the time or the inclination to make a photo essay to illustrate the difference but the OEM and M3 parts aren't even close to the same even with the naked eye.
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      06-22-2014, 12:29 AM   #12
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Quote:
Originally Posted by LMB335IS View Post
Dude, I'm telling you there's a difference. I have both in my garage. I don't have the time or the inclination to make a photo essay to illustrate the difference but the OEM and M3 parts aren't even close to the same even with the naked eye.
You're talking about the Tension arms and not the lower control arms yeah?

Bushes aside, what is the difference between the arms? M3 ones shorter?
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      06-22-2014, 12:34 AM   #13
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Also is the outer diameter of the bush shells exactly the same?
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      06-22-2014, 01:51 AM   #14
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Just to be crystal clear, I'm wanting to know if there is a difference between these two arms other than the bushes. I want to press M3 bushes into my arms because there does not appear to be any difference at all between the arms themselves. There isn't even an M badge on the OEM M3 tension arms. The logo that TRW grind off is a BMW logo, not an M logo. I believe they're the exact same forging but haven't had both in my hands to be 100% sure.

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      06-23-2014, 05:06 PM   #15
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I just did a lot of suspension work this past weekend, including M3 arms, and I can confirm the tension struts are exactly the same, except for bushings

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      06-23-2014, 07:11 PM   #16
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Excellent. Thanks Simon. Very handy to know.

Since mine has fairly low mileage and the ball joints are still all good, I'll just get a pair of bushes.
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      06-23-2014, 07:27 PM   #17
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Quote:
Originally Posted by simon View Post
I just did a lot of suspension work this past weekend, including M3 arms, and I can confirm the tension struts are exactly the same, except for bushings

I am interested in the same question. What year did those come off of, maybe that year used different arms? I have a 2006 330i sport and also want to do this same M3 arms/bushings upgrade soon. If my arms are the same and only the bushings are different then maybe I would get some Rogue Engineering bushings and have them pressed in.
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      06-23-2014, 08:27 PM   #18
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Came off an '07 E92 328 with sports package. I searched the part number for the right tension strut on realoem.com and sure enough the E90 330i does come up. I'd verify with the last 7 of your VIN on there if you're curious, though. Looks like the tension strut on my car (with hydraulic bushing) is the same for 328, 330, 335, 335is per realoem.

http://www.realoem.com/bmw/partxref....r=&series=E90N

edit: for whatever it's worth, the ball joint at the end was extremely loose compared to new arm. It didn't necessarily have any detectable play, but the difference between the two was shocking. The original arms had 102k miles on them
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      06-24-2014, 08:13 PM   #19
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Quote:
Originally Posted by simon View Post
Came off an '07 E92 328 with sports package. I searched the part number for the right tension strut on realoem.com and sure enough the E90 330i does come up. I'd verify with the last 7 of your VIN on there if you're curious, though. Looks like the tension strut on my car (with hydraulic bushing) is the same for 328, 330, 335, 335is per realoem.

http://www.realoem.com/bmw/partxref....r=&series=E90N

edit: for whatever it's worth, the ball joint at the end was extremely loose compared to new arm. It didn't necessarily have any detectable play, but the difference between the two was shocking. The original arms had 102k miles on them
Thanks, will be looking into this very soon.
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      06-30-2014, 10:44 PM   #20
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Quote:
Originally Posted by bradsm87 View Post
Excellent. Thanks Simon. Very handy to know.

Since mine has fairly low mileage and the ball joints are still all good, I'll just get a pair of bushes.
FYI Turner lists the large bushing as an Upgrade, even over the MyeleHD version.

Fortunately Lemforder and TRW sell the bushing separately for very cheap - see ECS tunning for an e9x M3.

Keep in mind these bushings need a pro to change and I've seen one instance here where the bushing hole was deformed.

Quote:
Originally Posted by banshee28 View Post
... I would get some Rogue Engineering bushings and have them pressed in.
The motivation to do the whole arm is that the small ball joint also wears out
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