Z4si and Z4M Aesthetics

[RVExotics]

I'm curious what all is aesthetically different about the si coupe vs. the M coupe. I know the front bumper, hood, and quad exhausts are different, but there's something about the way these cars photograph..sometimes one might look a little stubbier than the other, sometimes they appear to have the same contours. Do the ridges on the hood change the hood's contours on the M, or is it just my imagination? I've never been able to do a good side be side comparo of the two coupes in person.

[Starscream]

Ive had both and the look of the M in photos is night and day,

the non M hood almost makes the Z4 look boat like in the front, The lines in the M bumper change that and look great from the driving perspective too,
The M bumper makes the front end look "chunky" esp how it hangs down with its "fangs"

the back looks great too with the quad tails and the diffuer at the bottom of the bumper, It takes the sweeping look away from the non M bumper,

In all I think the only thing the M is missing stock is the Aero side skirts and I think they should have come stock on the M to complete the body transformation


Non M's still look hot though

[F87LUV]

Originally Posted by Starscream

Ive had both and the look of the M in photos is night and day,

the non M hood almost makes the Z4 look boat like in the front, The lines in the M bumper change that and look great from the driving perspective too,
The M bumper makes the front end look "chunky" esp how it hangs down with its "fangs"

the back looks great too with the quad tails and the diffuer at the bottom of the bumper, It takes the sweeping look away from the non M bumper,

In all I think the only thing the M is missing stock is the Aero side skirts and I think they should have come stock on the M to complete the body transformation


Non M's still look hot though

Nice save.

Isnt the suspension setup differently as well? Making the M look wider?

[MMMazing07]

The Z4M has a wider track for fatter tires and some negative camber

[enfield]

The Z4M seems to photograph really well from (either side - off centre) rear so that you get the curves and lines....

[Incompatible]

There's no mistaking the dual exhaust of the M. Mods will change the look in a subtle way for both the M and non M, but there is nothing subtle about the difference in the exhaust.

[The HACK]

Originally Posted by MMMazing07

The Z4M has a wider track for fatter tires and some negative camber

I'm not entirely sure the M actually has wider overall track. According to BMW specs, both the MZ4 Coupe and Z4 Coupe Si is 70.1" wide overall up front (which isn't surprising because the front offset is the same). According to the owner's manual the rear track width is 75" wide for the M, which is ALSO the same for the Si Coupe. What is different is the track width measured at the CENTER of the tire, the MZ4 Coupe is actually 3/10th" narrower than the Si Coupe.

What is also surprising is the Si Coupe is actually LOWER than the MZ4 Coupe. The overall height of the Si Coupe is 49.9", while the MZ4 Coupe is 50.67" high. Otherwise the wheelbase and overall length is the same.

I'm not even entirely certain the M has more negative camber. Prior to adding camber shims and knocking out the alignment pin up front, the stock front camber was only -1.4 degrees and the rear camber was -1.3 degrees, which is pretty close to the typical BMW negative camber settings.

[mPlasticDesign]

Originally Posted by The HACK

I'm not entirely sure the M actually has wider overall track. .....

The Mcoupe DEFINATELY has a wider track in front.

[MMMazing07]

dont remember where i read the wider track but it would make sense. defiantly from a liable source though. ill search around for it. about camber the rear camber for Z4M is between -1.6 to -2.1. the fronts im not too sure.


if they do have the same track then it would be possible to make the Z4 as stiff as the Z4M by just adding wider tires and new suspension. something doesnt sound right. im going to askl palatirion to come and chime in.

[F87LUV]

Originally Posted by MMMazing07

dont remember where i read the wider track but it would make sense. defiantly from a liable source though. ill search around for it. about camber the rear camber for Z4M is between -1.6 to -2.1. the fronts im not too sure.


if they do have the same track then it would be possible to make the Z4 as stiff as the Z4M by just adding wider tires and new suspension. something doesnt sound right. im going to askl palatirion to come and chime in.

Id be interested to hear more

but i think someone had posted otherwise when i made a thread about suspension... ill look for it

[The HACK]

Originally Posted by MMMazing07

if they do have the same track then it would be possible to make the Z4 as stiff as the Z4M by just adding wider tires and new suspension. something doesnt sound right. im going to askl palatirion to come and chime in.

Tire width and suspension does NOT affect the stiffness of the chassis. The Z4 Coupe Si and the MZ4 Coupe has the same identical torsional rigidity number at 32,000Nm per degree of deflection.

As for the front track of the MZ4 Coupe being wider, BMW's own numbers and measurements suggest otherwise. See diagram attached.

Not saying BMW NA is the end-all, be-all source (they've made mistakes in their press materials in the past), but right now I'm inclined to believe their numbers since it's the only source I have to go by.

EDIT: Now that I had re-read the thread I think you mean to make the Z4 Coupe Si's suspension as stiff as the MZ4 Coupe. The problem in assuming that, is the MZ4 Coupe's front and rear suspension design is completely different than the Z4 Coupe Si. You can add aftermarket suspension to make the Z4 Coupe Si handle just as good or better than the MZ4 Coupe, there's no denying that. You can not, however, make the MZ4 Coupe suspension work on the Z4 Coupe Si since almost all of the mounting points and geometry is different. The MZ4 Coupe uses a customized front suspension from the E36 M3 and a nearly complete carry-over of the rear suspension from the E46 M3. The diff carrier, trailing arm, upper control arm, rear subframe, lower control arm, will need to be replaced for the Z4 Coupe Si to take the rear suspension from an MZ4 Coupe, and I don't think the front suspension can be made to work on the Z4 Coupe Si at all.

[The HACK]

Originally Posted by ///Metak

The Mcoupe DEFINATELY has a wider track in front.

Can you supply the source of that information? I would love to be able to confirm this as well.

[enlightenment]

The height difference is most likely from the wheels.

[The HACK]

Originally Posted by enlightenment

The height difference is most likely from the wheels.

Good point. The MZ4 Coupe wheel/tire size is almost 1" larger in diameter. leading to ~.5" difference in height.

Thanks for pointing that out.

[mPlasticDesign]

Originally Posted by The HACK

Can you supply the source of that information? I would love to be able to confirm this as well.

I thought this was common knowledge? I have read this in almost every publication from Bimmer to R&T. Here is a Car and Driver test on the Roadster, but they share the same suspension as the coupe:

"...The front track is a half-inch wider than the Z4's, the forged-aluminum lower control arms locating the bottom end of the struts are essentially the same as those employed in the M3..."
http://www.caranddriver.com/reviews/..._test/(page)/1

[The HACK]

Originally Posted by ///Metak

I thought this was common knowledge? I have read this in almost every publication from Bimmer to R&T. Here is a Car and Driver test on the Roadster, but they share the same suspension as the coupe:

"...The front track is a half-inch wider than the Z4's, the forged-aluminum lower control arms locating the bottom end of the struts are essentially the same as those employed in the M3..."
http://www.caranddriver.com/reviews/..._test/(page)/1

Oh wow...Did C&D ever get their information wrong. The lower control arm on the bottom of the strut is DEFINITELY nothing like that of the E46 M3 (or even E36 M3 for that matter). The lower control arm on the MZ4 Coupe is the same as what came on the E46 330i with Performance Package. It is also the same lower control arm used on the 320i motorsports chassis used in European Touring Car Championship. There's some significant design differences between the E46 M3 front LCA to what's used on the MZ4 Coupe. In fact, the MZ4 Coupe shares only one single suspension component up front with the E46 M3. The anti-roll bars are the same as what's on the M3 CSL.

E86 M4oop
http://www.realoem.com/bmw/showparts...79&hg=31&fg=05

31122282121 Left wishbone
31122282122 Right wishbone

E46 330i
http://www.realoem.com/bmw/showparts...00&hg=31&fg=05

31122282121 Left wishbone
31122282122 Right wishbone

E46 M3
http://www.realoem.com/bmw/showparts...76&hg=31&fg=05

31122229623 Left wishbone
31122229624 Right wishbone

Now, the ZHP LCA is a little bit wider than the normal 3 series LCA, but we can't just assume that because the LCA on the M4oop may possibly be wider than the Si Coupe that it means the M4oop front track is wider. We have got to keep in mind that the rest of the M4oop front suspension is so different from the Si Coupe that other factors may make it so that the front track ends up being the same width after all. There's still no confirmation that the M4oop is indeed wider unless we can get one to measure against an Si Coupe?

EDIT: There's nothing online that should ever be taken as "common knowledge."

[mPlasticDesign]

Originally Posted by The HACK

Oh wow...Did C&D ever get their information wrong. .....
EDIT: There's nothing online that should ever be taken as "common knowledge."

I can already tell you are never wrong, but here you go. Take it or leave it. These are the numbers from BMW's international website. These measurements are more accurately reported in mm's rather than the rounded inches used in the bmwusa site.

Works out to ~1/2inch difference.

[mPlasticDesign]

Here's the math: 1473mm/2.54cm=57.99in vs. 1486mm/2.54cm=58.50in

[The HACK]

Originally Posted by ///Metak

I can already tell you are never wrong, but here you go. Take it or leave it. These are the numbers from BMW's international website. These measurements are more accurately reported in mm's rather than the rounded inches used in the bmwusa site.

Works out to ~1/2inch difference.
Attachment 174512

Originally Posted by ///Metak

Here's the math: 1473mm/2.54cm=57.99in vs. 1486mm/2.54cm=58.50in

I'm not trying to be a d*ck here, I'm just asking for validation. It's great that you can find information to back it up, thank you very much for your research.

Now that it is proven that the front track is indeed wider, I guess you OWN me and I should probably just shut the hell up and never post here again. Sorry for the inconvenience.

And C&D is indeed wrong. The E46 M3 LCA is very different in design to the E46 330i ZHP and MZ4 Coupe LCA.

[mPlasticDesign]

Originally Posted by The HACK

I'm not trying to be a d*ck here, I'm just asking for validation. It's great that you can find information to back it up, thank you very much for your research.

Now that it is proven that the front track is indeed wider, I guess you OWN me and I should probably just shut the hell up and never post here again. Sorry for the inconvenience.

And C&D is indeed wrong. The E46 M3 LCA is very different in design to the E46 330i ZHP and MZ4 Coupe LCA.

No one is saying you can't post here. I was concentrating on the front track difference. It's just that you kinda went off on a tangent, that's all.

[Palantirion]

Originally Posted by The HACK

The Z4 Coupe Si and the MZ4 Coupe has the same identical torsional rigidity number at 32,000Nm per degree of deflection.

-Any idea what the torsional rigidity #s are for other Z4 M competitors?

[F87LUV]

hey guys, dont stop posting... its good that we finally have people actually discussing Z/Ms!!