Differences Between Non-M and M3 Suspension

Gotcha. Thanks so much for the clarification.

Originally Posted by ZHP6

Is there a way to swap those in as well, or do you need the E46 M3 subframe? I'm trying to figure out if it's possible to get at least 7 degrees of caster with camber plates and a few mods.

I've done exactly that. Front subframe was left stock (it's already the same part number as the M3).
http://forum.e46fanatics.com/showpos...&postcount=487

Originally Posted by cyberkaa

I've done exactly that. Front subframe was left stock (it's already the same part number as the M3).
http://forum.e46fanatics.com/showpos...&postcount=487

not that it matters for the info of swaps. but although the front subframe may be the same mounting points. the M3 uses the stronger front subframe from the convertible and not the coupe/sedan. it's different.

Originally Posted by Alex323Ci

not that it matters for the info of swaps. but although the front subframe may be the same mounting points. the M3 uses the stronger front subframe from the convertible and not the coupe/sedan. it's different.

The x-ref list here shows the same part:
http://realoem.com/bmw/partxref.do?part=31111096902

Do you have a side-by-side comparison?
That was one thing I was unable to verify except by memory since the M3 subframe was off at a different time.

Originally Posted by Alex323Ci

not that it matters for the info of swaps. but although the front subframe may be the same mounting points. the M3 uses the stronger front subframe from the convertible and not the coupe/sedan. it's different.

Are you sure you aren't talking about the underbody reinforcement brace 51717893609? That is a different part, only used on the M3 and the Z4 Ms

Originally Posted by cyberkaa

The x-ref list here shows the same part:
http://realoem.com/bmw/partxref.do?part=31111096902

Do you have a side-by-side comparison?
That was one thing I was unable to verify except by memory since the M3 subframe was off at a different time.

I don't have comparison. This is specifically listed by BMW in the M3 specs pages.
As for the part number, I suspect they just stock the one now for replacement just like the rear subframe panel. The stronger convertible version.

Originally Posted by mkodama

Are you sure you aren't talking about the underbody reinforcement brace 51717893609? That is a different part, only used on the M3 and the Z4 Ms

No I'm not talking about the aluminum plate.

You've got me curious. Do you have a link to the specs pages?

Originally Posted by cyberkaa

You've got me curious. Do you have a link to the specs pages?

i figured you wouldn't believe me.
last line of the E46 M3 FRONT SUSPENSION SPECS

Originally Posted by Alex323Ci

i figured you wouldn't believe me.
last line of the E46 M3 FRONT SUSPENSION SPECS

[IMGhttp://img.photobucket.com/albums/v188/showitsam/IMG_0389_zps12e583be.jpg[/IMG]

Well, don't be so hard on yourself. It's not that I didn't believe you, but I wanted to see the source. There are a lot of details there that we can independently verify.

Specifically, I'm thinking that since I have 2000 323ci, 2003 325i, and a 2002 M3 at my house right now, I can check all of the subframe part numbers if they're still visible and verify that claim.

So all in all, is it possible to swap out springs only from an m3 to a 330i?. By the looks of it, im gonna have to hunt for an m3 being sold for parts ..its time for a little suspension "love" anyway

Originally Posted by Orchazum

So all in all, is it possible to swap out springs only from an m3 to a 330i?. By the looks of it, im gonna have to hunt for an m3 being sold for parts ..its time for a little suspension "love" anyway

The the springs looked interchangeable. Same diameter and ends, etc. They are a good deal higher of a spring rate though, so with used non-M dampers, you're probably going to get a very bouncy ride.

Yaaa im not going for the ***** look hahahahah. Thank you for the input however... Much appreciated

Sent from my SPH-L710 using Bimmer App

I'm doing this swap this week and was wondering what the best position for the three top mounting bolts to be positioned for the closest to factory specs for non-M?

Originally Posted by Cpconst

I'm doing this swap this week and was wondering what the best position for the three top mounting bolts to be positioned for the closest to factory specs for non-M?

Probably the position that moves the strut bearing pivot point forward. Camber adjustment stays pretty much the same as a non-M, but there is a small loss in caster/self centering of the steering.

In that last picture of the strut bearing:
Rotated 240 degrees clockwise from original, it seems to give the highest camber and caster when used on non M.

Has anyone set it like this and performed a wheel alignment ?

What is the measurement for camber and caster ?

Visually I would guess around -3 degrees camber.

Anyone have data or a more educated guess ?

Just to be clear ride height stays about the same in the rear and raises a little in the front? I was just curious what the reason for this was? Thanks guys

Originally Posted by Mccomasg09

Just to be clear ride height stays about the same in the rear and raises a little in the front? I was just curious what the reason for this was? Thanks guys

The ride height looks about the same as non-M sport suspension.

The rumor was that M3 front springs would raise the front of a non-M because they were designed to support the heavier M3 engine, but there was nothing noticeable to me.

Thanks for the reply, and what did you notice were the biggest benefits? And any negatives? I got a good deal on some and I need new struts, I prefer to stay oem everything but if there is no negative I wouldn't mind swapping them out?

Originally Posted by Mccomasg09

Thanks for the reply, and what did you notice were the biggest benefits? And any negatives? I got a good deal on some and I need new struts, I prefer to stay oem everything but if there is no negative I wouldn't mind swapping them out?

The installation wasn't on my car, so I can't give any helpful info there. Try messaging Devious21 or hizhinezz.

Non-M struts are partially compressed at rest position, fluid can be heard if shaken, and easier to compress, strongly suggesting a low-pressure twin-tube design. M3 struts are fully extended at rest, no fluid can be heard if shaken, and are harder to compress, strongly suggesting a high-pressure mono-tube design."

I know for a fact that non-M-shock-absorbers are twin-tube-design. However - the OEM-Sachs-shocks on my 330 (M-package) did fully extend in resting position (even after 5 years / 90.000km). Even the rear ones that were leaking oil did fully extend - indicating that there was still pressure inside.

Same goes for my brand new Bilstein B4 replacement shock absorbers which are listed as twin-tube-design - they fully extend - all by themselves. If your E46 Sachs/Bilstein shocks dont fully extend its likely they are worn out/shot/dead. I know - there are cases were brand new twin-tube-shocks dont fully extend but the twin-tube Sachs/Bilstein E46 shocks do!

Note: twin design shocks break down slowly. They even work (kind of) when they are in the process of failing. This is why a lot of people dont notice that their shocks are gone. It usually happens so slowly that they get used to feel. Mono-tubes usually last longer than twin-tubes but when they fail -> you know immediately

BTW - if you look up the E46 M3 shocks in the Bilstein catalog you will see that the B4 replacement shocks are listed as twin-tube-design as well. That of course does not prove that the OEM M3 shocks (I guess Sachs) are twin-tube-design but its an indication.