Strange Suspension Dimension Question

TheDan · Post by **TheDan** » Tue Mar 12, 2024 11:39 am

Hi all,

Maybe a bit of a strange question this morning...

Other than the lollipop bushes, are the non-M Z4 and Z4M lower control arms (wishbones) the same geometry/dimensions?

I have read somewhere that the front track of the Z4M is around 0.5in wider each side and wonder if this comes from the control arms or the inner ball joint mounting to the frame/cross member?

enuff_zed · Post by **enuff_zed** » Tue Mar 12, 2024 1:01 pm

A quick plug in on Autodoc says the standard ones are NOT compatible with M models

TheDan · Post by **TheDan** » Tue Mar 12, 2024 3:11 pm

Sorry, I probably should have put a bit more clarification on my original post.

I am looking at increasing negative camber to in the region of -2.5 to -3 for track. The problem I have is even with adjustable camber top mounts maxed out (damper top nut against the shock tower hole) I only get -2 degrees.

I've heard that some E46 owners have put the E46 M3 lower control arms due to them being longer between the inboard and outboard ball joints, which effectively adds negative camber. The only problem with the E46 M3 lower control arms is I'd have to change the kingpin also as the ball joint is an M14 and not an M12.

I was wondering if the Z4M lower control arms also had this extra length between the two ball joints, but if the outboard ball joint was still M12 like the non-M Z4.

enuff_zed · Post by **enuff_zed** » Tue Mar 12, 2024 3:21 pm

OK.
If you go into Autodoc, add the M to your car list, then select the suspension arm. On 'more info' it gives you Thread size. There are a few illustrations and the last one shows you dimensions.
On the M arm the distance from inner ball joint centre to outer ball joint centre is 355mm and the distance from inner ball joint centre to rear of the lollipop pin is 338.5mm
On the non-M arm the distance from inner ball joint centre to outer ball joint centre is 355mm and the distance from inner ball joint centre to rear of the lollipop pin is 340.5mm.

Therefore, while they are different, the measurement you are asking about seems to be the same on both.

Given that the M has hydraulic steering, my guess would be that the cross-member is different and therefore it is the inner locating point of the arm that is further out.

TheDan · Post by **TheDan** » Tue Mar 12, 2024 4:00 pm

Ah I see, thank you so much as that is exactly what I was asking!

I didn't know some of the parts on Autodoc had drawings associated with them.

This sort of brings me onto my next question:

Is the brake caliper mounting the same between the non-M Z4 and Z4M? Ie same hole centres?

enuff_zed · Post by **enuff_zed** » Tue Mar 12, 2024 4:28 pm

TheDan wrote: ↑Tue Mar 12, 2024 4:00 pm Ah I see, thank you so much as that is exactly what I was asking!

I didn't know some of the parts on Autodoc had drawings associated with them.

This sort of brings me onto my next question:

Is the brake caliper mounting the same between the non-M Z4 and Z4M? Ie same hole centres?

You just know I'm going to tell you to check for images on Autodoc.

TheDan · Post by **TheDan** » Tue Mar 12, 2024 7:00 pm

Haha yeah I know!

I did have a quick gander, but they don't stock king pins/spindles.

Thanks for your help on this though!

enuff_zed · Post by **enuff_zed** » Tue Mar 12, 2024 7:12 pm

TheDan wrote: ↑Tue Mar 12, 2024 7:00 pm Haha yeah I know!

I did have a quick gander, but they don't stock king pins/spindles.

Thanks for your help on this though!

Right! Think laterally.
Standard caliper on Autodoc. Check out the 'more info' and it says 'Mounting Bore Distance - 94mm
For the M it says 95mm

Here endeth the lesson.

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