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Differences Between Non-M and M3 Suspension

157K views 100 replies 42 participants last post by  A930rocket 
#1 · (Edited)
Here is some info and pictures about both setups.


Struts, front: Interchangeable only with appropriate strut bearing assembly, bump stops(if used), and dust boots(if used).
Strut mounts, front: Interchangeable only with appropriate strut and removal of factory alignment pin. NOTE: Changes alignment range.
Shock and mount, rear: Interchangeable
Springs, front: Interchangeable only with appropriate strut mount assembly or modification of spring.
Springs, rear: Interchangeable
Anti-sway bars, front: Interchangeable only with appropriate bushings and brackets
Anti-sway bar, rear: Not interchangeable (forum supplied information; reasonable to believe because of dimensionally different rear subframes, differentials, and difference in spare tire well)


Strut assembly pieces in order:

Stock Non-M:


Stock M3:





The M3 strut bearings are mirrored left to right and have an offset strut attachment hole that changes alignment between the M3 and non-M. The non-M strut bearings have a concentric attachment hole and are identical left and right. The M3 strut bearings can be clocked or swapped left to right to change the alignment range; the factory alignment pin must be unscrewed to do so. I am not sure of any long term integrity or accelerated wear problems caused by this, but I have observed no ill effects on two non-Ms with modified position M3 strut bearings.

Original M3 position strut bearing orientation on left strut; reducing camber and increasing caster compared to non-M:


M3 strut bearing rotated 120 degrees clockwise from original position; decreases camber and decreases caster compared to non-M, increases camber and decreases caster compared to original:


M3 strut bearing rotated 240 degrease clockwise from original postion; increases camber and increases caster compared to non-M, increases camber and decreases caster compared to original:



Underside of M3 strut bearings showing they have substantially more material, are designed for much greater rigidity, and a larger, stronger, sealed bearing is used, greatly increasing service life and reducing chances of strut tower mushrooming with the downside being roughly $90 more expensive per strut bearing:




Non-M struts are partially compressed at rest position, fluid can be heard if shaken, and easier to compress. M3 struts are fully extended at rest, no fluid can be heard if shaken, and are harder to compress.

Non-M left, M3 right


The threaded shaft length above the taper is why non-M(left) and M3(right) struts must be used with the appropriate strut bearings and vice versa:



Appearance, ride, and handling of M3 suspension on a non-M: M3 suspension on a non-M looks similar to non-M sport suspension in terms of ride height, but spring rates are considerably higher and damping is much greater as well. There is no noticeable lift in the front relative to the rear as rumored by some people. The ride feels very similar to an M3 meaning much more road feedback and the car follows the road more sharply. I haven't driven any of these cars hard enough to comment on at-the-limit handling.


*Everything here is through actual experience from working on and driving multiple E46 unless stated. This only info only applies to US market M3 and rear wheel drive non-M.
 
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#50 ·
The M3 suspension have benefits if you want a sportier ride and more aggressive alignment compared to non-M suspension, and the design of the strut mounts is stronger and longer lasting.

If you don't want to make your car sportier and deal with a rougher ride and altered alignment settings, then no, there aren't any benefits. Functionally, everything is very similar, that's why they can be swapped.
 
#54 ·
Yes, the rear setup is a direct fit.
M3 strut mounts don't fit properly on non-M dampers. The fronts will fit with non-M strut mounts, but keep in mind that the camber and caster will change relative to the original M3 suspension. Camber plates would be a good addition.
 
#61 ·
Just for arguments' sake, and for temporary transportation only I have one more brain teaser:

- Would the front struts off a 325i (non-sport suspension) fit an M3?
- I realize the alignment pin on one strut mount will need to be shaved off.
- The M3 front coil looks more compact.

I am worried about clearance issues between the wheel and front struts.


Just to clarify: 325i suspension --> to M3
 
#62 ·
You could use the whole 325i strut, spring, and hat assembly on the M3. I'm not sure about change in clearance to the wheel, but with stock wheels, it probably would not be a concern.
 
#63 · (Edited)
To update my question above, YES - a non-sport 325i suspension will fit on the M3. This was for temporary transportation ONLY.

BUT, both rubber bushings ended up popping out of the RSMs, and I essentially completed the last 20mi of my trip home on only springs in the rear.

My obvious assumption would be that the non-sport rear springs were a bit too tall for the RSMs to handle.
That, or the 14 year old components just couldn't take it anymore. Once the first RSM popped, the 2nd was due within minutes.
 
#64 · (Edited)
M3 swapped top hat pss9 not rotated in non m zhp question

First off thank you for the detailed info. I have searched and found swapping but not rotating m3 top hats in an m3 yields 2.5 to 3 degrees negative camber, does anybody know what the resulting camber would be on a non m using m3 top hats swapped left to right but not rotated and struts or pss9 from m3 assuming stock or only slightly lowered ? I'm assuming it's not -2.5 to -3 since our stock non m hats are centered therefore not exactly apples to apples. Thanks in advance. I have free access to hunter alignment rack and I'm happy to update with my results , just trying to do as much homework as possible. This is for a 2003 zhp it has z4 m offset front bushings but still in zhp spec caster on hunter alignment machine. I looking to see if I can make a streetable alignment with all parts I have in stock ... M3 strut brace m3 top hats m3 pss9s I would like camber between -1.2 to -2.5 w stock ride quality top hats if possible. Not looking to spend 400$ on adjustable hats at the moment, but I will wait to do it that way if needed.
 
#65 ·
Big up-- to all the gurus and experts, I need your help and advice. I recently installed the Koni FSD and Eibach sport kit from ECS. Now the car looks good and drive good but it is a bit too low for NY streets about 1/2". Now for some details.All 4 Wheels rubs occasionally on dips and hard cornering with me and a passenger. Checked the front suspension and noticed that with the car jacked up the springs can be turned by hand. And the car has to be jacked way up before the wheels leave the ground There is almost no tension on them (spring). It seems like the struts shaft is too long. I was looking at the pictures of the struts in your posts and there seems to be a significant difference in none M and the M struts shafts length. I know and understand that the neck that goes into the struts mounts are different but my concern is the shaft travel. Now to eliminate the rubbing do I need taller spring or springs with higher spring rate or what? ???. BTW my wheels are 225 40 18 in front and 255/35 /18 in rear. I will post pictures of how low the car is tomorrow. I'm thinking that about 1/2" gain in height would eliminate most of if not all of the rubbing. Any and all advice and recommendations are appreciated.
 
#66 ·
pic's of lowered suspension

Before you could see the struts over the tires and now my fingers can't pass between tires and fenders, but it drives great not bouncy not hard and cornering with little to no body roll except for the occasional rubbing. I am almost positive that a 1/2" gain would cure the rubbing.
 

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#68 · (Edited)


Can anyone tell me can this Control arm bushing be used on a non M model?

Im fairly sure i have it from my old E46 M3 and I'm now needing to change the bushing on my current 325ci. Can this be used even tho the whshbone is different? I can pick up a regular Control arm bushing next week but i wanted to get this job done over the weekend if this part i have will fit.
 
#72 · (Edited)
Hey Mkodoma, thanks for the write up. I actually wanted to try this since I had a spare set of M struts laying around. Did the install however, I swapped the bearings from left to write and vv. I wanted to get max amount of Castor out of this setup, instead of looking for camber. That being said, by pushing the tops all the way toward the engine in the slots, I believe I am now running about 1.5 -1.8 camber, which is more than what I had before.

Here is what I found though: My car came with factory sport suspension and, unfortunately the M3 struts are taller and raised my car about 0.75 to 1".
Not worried about it since, this was just a 'test' to see how the non-coilover setup would play out. So, with this test, I am now ready to spend money on new stuff and will be purchasing H&R springs for the M3 (0.75 -1" lowering) that should return my Sport suspension ride height.
Will also buy new Bilsteins and will throw in a set of Z4M lower eccentric control bushings (in search of more caster).

Otherwise, the handling after the swap, even though the M3 shocks are blown, are freaking unbelievable. Having extra caster gives me more dynamic camber at 20 percent lock and, all the previous understeer under "street conditions" are gone.
The only thing is, since the front end has been raised, the roll center has also changed that could also contribute to better handling and less roll.

Otherwise, valving between the Non-M and M dampers: Seat of the pants dyno is telling me that, Bound valving is about the same between the two however, the rebound is definitely stiffer on the M. In addition, I believe the M springs are about 50lbs heavier up front.
Anyhow, I figured I'd provide you with some feedback as well as a photo.

The taller strut is the M on the left.

http://s577.photobucket.com/user/bayern_munchen/media/M3 struts vs_zpspr62nmlv.jpg.html

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#73 ·
Otherwise, the handling after the swap, even though the M3 shocks are blown, are freaking unbelievable. Having extra caster gives me more dynamic camber at 20 percent lock and, all the previous understeer under "street conditions" are gone.
The only thing is, since the front end has been raised, the roll center has also changed that could also contribute to better handling and less roll.

Otherwise, valving between the Non-M and M dampers: Seat of the pants dyno is telling me that, Bound valving is about the same between the two however, the rebound is definitely stiffer on the M. In addition, I believe the M springs are about 50lbs heavier up front.
Anyhow, I figured I'd provide you with some feedback as well as a photo.

I noticed a pretty big handling difference between the m3 struts/shocks/springs compared to my previous two setups. Which were shitty raceland coilovers (car came with them) and factory sport suspension.

The front did sit higher compared to the sport suspension, but the rear was exactly the same. To eliminate this I simply put thicker spring pads in the rear (top and bottom).

It's a cheap upgrade IF you can find all I the parts together and IF they have low milage. And you get better handling than sport suspension.
 
#74 ·
Hi,
I ahve one specific question and I am not sure whther someone already tried this or not.

As far as I can find, I have an issue to change the rear shocks on sport suspension coupe. I have factory shocks, which are really on the end of their lifetime and I want to change them for aftermarket, as OEM are quite pricey.

Unfortunately Sachs stopped producing the rear shocks for sport suspension and they sell only standard ones, Bilstein are well known for early failures last few years, Konis are rusting as hell, KW are pricey and I do not believe in quality of the rest.

However rear schocks from M3 are direct fit, my coupe is sitting on Eibach Pro Kit springs, and Sachs still sells aftermarket shock on BMW E46 M3.

My question is, whether is it good idea to have combo of Sachs Sport Front (non-M3) and Sachs M3 rear (all on non-M Pro Kit Eibach). The car is 320ci M52, rear axle is mounted on powerflex black bushings and quaife torsen differential.

Thank you for your input.
 
#75 ·
You are mixing non OEM spring rates with OEM but not model specific valving...I don't know man, I am sure it will work - to get you from point A-B but, will the car be balanced? Probably not.
I swapped the M3 struts/springs/plates and rear springs only, onto my 325ci. While the front end is pretty much hooked up (due to raised ride height, corrected roll center and added +castor), the rear end does this funny swing on bound.. Obviously, the OEM non-M dampers are under-valves for the M3 rear springs... That, or my rear dampers are just that* worn. Either way, I wouldn't mix (again) front to back if it was me.
 
#76 ·
If I understand coreectly, you do not recommend the m3 shock with non-m3 spring, as the shock could have different working position?
Because regarding the spring, i understand Ou need to have the coreect one build on the weight level od the vehi***263;le (which I have as the spring is suited to my car). However the shock should not be dependant on weight of the car, they can be however dependnt on height of the spring....
I have to think about it. My concwrny were however regarding the fornt/rear balance as I can inagine that rear shocks from m3 will be much stifer.
I came ober this idea as Bilstein recommends to use b6 bmw m3 e36 shocks instead od their b6 e46 for x-drive models.
 
#81 ·
I will agree that I would not use a stock OE type Non-M rear damper to try to control a E46 M3 rear spring. A damper like that will have "poor" control over the higher spring rate M3 rear spring, a bouncing issue will most likely happen.

On the flip side, using some sort of stock OE type M3 rear damper with a Non-M rear spring works just fine.



Rob43
 
#82 ·
Anyone know the difference between the Rear Trailing Arms from an M3 Part Number (33322229685 left and 86 right) and the one on a 330i Part Number (33326774779 left and 80 right). They look the same in Real OEM but wondered what the difference is and if it would be an upgrade as I am at a point of replacing the bushings.
 
#84 ·
Hello from Australia

I have a non M coupe and it has done 170,000km. The suspension needs overhauling as it is squishy and sagging. The shocks and springs need replacing.
I was quoted roughly $1000 to get a full set of Koni STR-T (orange) struts and shocks, including mounts and bump stops. This still didn't address the problems I was having with my springs.
I saw someone on eBay was selling a set of OEM struts, shocks and springs from an M3 with only 70,000km for $100. They didn't have the top strut mounts, bolts, plates or bearings though.

I jumped on them and purchased them.

I now need to purchase the top mounts and other bits. The cheapest I can see is from ECS tuning, which will cost me $450 US +$130 shipping.

If I buy the M3 mounts and all the bits, will they just fit on?

I have read this entire thread and I am confused. Will my camber be effected terribly with the installation of the M3 parts?

Any help is appreciated.

Thanks
 
#85 ·
Check rmeuropean.com, they have the plates for 150 each. Or, look for used ones on eBay.

Installing the M3 struts will raise your front end by about 25mm. If installed the way it was intended(left to left, right to right) your negative camber will be about 0.75, positive camber about + 5
You can swap them L to R to gain additional positive caster which is what I have done.
Hope this helps. Let me know if any additional questions.
 
#88 ·
Sport Wagon

Does anyone have any insight into using M3 springs in a Sport Wagon with Sport suspension?
I installed the H & R Sport springs that are Wagon specific, and they are just too low for a daily driver. I was thinking about the M3 springs, since the higher spring rate, especially for the rear, would be a good choice as an alternative to the OEM Sport springs in a wagon. I have and int to keep my Koni yellows, so I assume I'll have to cut a half coil off of the fronts to keep my stock hats,...
 
#89 ·
I have read through this post and I understand that pretty much springs, dampers and sway bars are interchangeable between the regular e46's and the e46 M3 as long as the bushings and strut bearings are changed as well.
I have 2002 M3 vert which I love driving but being 66 I am starting to find the suspension a bit harsh. Same goes for my wife.It is a DD on nice days and I never track it and honestly don't drive it too hard, but I do like the power delivery when I step on the gas. If I wanted to modify my suspension towards the comfort end of the spectrum would swapping out the springs, dampers and sway bars from say a 300CI ZHP vert move me away from the harshness of the normal M? ride? My wife has 2003 325i sedan and after driving the M3 I do find it a bit bouncy so I do not want to go to that end of spectrum. I have never driven a 330 ZHP so I don't have much to compare to. I am also considering to sell the M3 and buy an E93 335.435i ( or maybe 330CI ZHP). I do have 2006 E91 wagon so I know the feeling somewhat of the suspension of that generation but I really like the communicative nature of the e46 chassis. . You guys are much more well versed in these nuances than I am so please chime in and help me sort this out!
 
#90 ·
I have 2002 M3 vert which I love driving but being 66 I am starting to find the suspension a bit harsh.. If I wanted to modify my suspension towards the comfort end of the spectrum would swapping out the springs, dampers and sway bars from say a 330CI ZHP vert move me away from the harshness of the normal M? ride?
I would probably look into changing out the springs to a softer aftermarket M3 one.
Then buy some less sporty tires next time, as some higher end speed rated tires have overly stiff sidewalls.
Your M3 convertible is heavy, so springs from other cars prob not so good.
ZHP springs btw are same as ZSP (Sport Package).
Convertibles usually take a different spring rate in rear (than coupes) because of their additional weight.
 
#91 ·
From everything I read it seems that ZHP is a more comfortable DD than the M3 although I have never driven one so can’t compare first hand. I also understand that the handling of a ZHP is more sport oriented than a plain Jane e46. So I figured that the stiffness of a ZHP version had to be somewhere between a regular e46 and an M3. The weight of a ZHP vert and my M3 vert must be very close with regards to spring rates so it would not seem that I would need to compensate for any extra weight due to my car being a vert. This makes me think that swapping in a ZHP suspension might be a good solution. I used to have the Michelin A/S3 on the rear and now have the Conti DWS 06 all season and the rear doesn’t seem any more compliant than before. I wonder if anyone who has driven both could comment on the stiffness between the two and also on the compatibility with swapping in the parts and what I would have to look out for.
 
#92 ·
It would be great if someone could comment on this approach or another that will get me to a somewhat softer suspension setup for my M3 vert. I can swap out suspension parts myself but I would like to know before jumping into an exercise like this that it will get me to where I want to be. I don't have the time or resources to be messing around with my suspension until I get it right. It would be great if someone could help me get together a list of parts that will fit and work and soften up my setup.
PS: other solutions I am considering are to sell the M3 and buy 330 vert ZHP or maybe plain Jane 330ci or buy an e93 335i. Thanks for your collective input
 
#93 ·
Hi guys, have a question. I have a e46 323 convertible. Its currently got ac schnitzer springs, correct for the model of the car. However the struts are blown. I have found a set of M3 ac schnitzer struts. I see from this post that the rear struts will fit, which i assumed they would. However, if I use the front M3 strut and top hat, will my current non M3 springs fit? AC schnitzer uses the same mounting designs as factory if that helps.
 
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