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Z4M - Suspension Help

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mr wilks
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Z4M - Suspension Help

Post by mr wilks » Tue May 08, 2018 9:49 pm

bmwaddict wrote: Tue May 08, 2018 9:46 pm
mr wilks wrote: Tue May 08, 2018 7:12 pm
bmwaddict wrote: Tue May 08, 2018 7:09 pm Nice, but a bit too harsh for the roads I drive on, they're lower than the Eibachs you get in the B12 kit.
Still on the original shockers ?
Yes, which is definitely a contributing factor.
For sure
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Z4M - Suspension Help

Post by MrPT » Tue May 08, 2018 10:27 pm

mmm-five wrote: Tue May 08, 2018 9:11 pm I don’t think you’ll get it anywhere near as compliant as the others you’ve mentioned, except maybe close to the M3.

Even compared to the M3, I think you’re finding a combination of issues really:
  • higher torsional rigidity
  • shorter wheelbase
  • sitting right over the rear wheels
  • thinly-cushioned seats
My mates CSL with Recaro buckets feels more compliant than my Z4MC, and is much more fun to drive at 9/10ths on a bumpy B-road than a standard Z4MC, and I’d have gone for one of them if I hadn’t been planning on putting 150k miles on it.

Coversely, when I tried an e9x M3, it felt like a blancmange compared to the Z4MC - and seemed to take a long time to settle into a steady position on corners, so you had to turn earlier than you’d expect - felt more like my lardy e34 M5, which is both a good thing (for an autobahn stormer) and a bad thing (for a fast-road/track sports coupe).
+1

It’s a fundamentally unsettling car to drive. How much of that is perceived due to the layout and how much is caused by the chassis and suspension set up, I’m not sure.

The KWs I have definitely sort out the crash/unrefined behaviour, but the rear is still very lively.
Last edited by MrPT on Tue May 08, 2018 10:32 pm, edited 1 time in total.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Z4M - Suspension Help

Post by mc5 » Tue May 08, 2018 10:31 pm

So how does it handle pot holes on your fancy KW v3. Does it absorb them or make a crashing thump

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Z4M - Suspension Help

Post by MrPT » Tue May 08, 2018 10:34 pm

mc5 wrote: Tue May 08, 2018 10:31 pm So how does it handle pot holes on your fancy KW v3. Does it absorb them or make a crashing thump
Hah, I just edited to add a point on that. Really good, yeah - reminded me of my friend’s 911 is the way it just “thunked” in and out of dips in the road when I first drove it. A friend with a 3.0si commented on this as well in a back-to-back comparison.
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Post by MrPT » Tue May 08, 2018 10:40 pm

Wait a second. How big are these potholes and why are you driving over them? :?

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Z4M - Suspension Help

Post by mc5 » Tue May 08, 2018 10:57 pm

I never spot them lol. Big drain covers can be an issue to. Guess coilovers could be the only answer. 90% of the time its fine on the bilsteins its the odd time thatcan send a thud through front that be annoying. Never had this in Porsches, m3s or s2000s. Luckily the rest of the car makes up for it :)

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Post by RedUn » Wed May 09, 2018 12:11 am

MrPT wrote: Tue May 08, 2018 10:27 pm
mmm-five wrote: Tue May 08, 2018 9:11 pm I don’t think you’ll get it anywhere near as compliant as the others you’ve mentioned, except maybe close to the M3.

Even compared to the M3, I think you’re finding a combination of issues really:
  • higher torsional rigidity
  • shorter wheelbase
  • sitting right over the rear wheels
  • thinly-cushioned seats
My mates CSL with Recaro buckets feels more compliant than my Z4MC, and is much more fun to drive at 9/10ths on a bumpy B-road than a standard Z4MC, and I’d have gone for one of them if I hadn’t been planning on putting 150k miles on it.

Coversely, when I tried an e9x M3, it felt like a blancmange compared to the Z4MC - and seemed to take a long time to settle into a steady position on corners, so you had to turn earlier than you’d expect - felt more like my lardy e34 M5, which is both a good thing (for an autobahn stormer) and a bad thing (for a fast-road/track sports coupe).
+1

It’s a fundamentally unsettling car to drive. How much of that is perceived due to the layout and how much is caused by the chassis and suspension set up, I’m not sure.

The KWs I have definitely sort out the crash/unrefined behaviour, but the rear is still very lively.
What geo are you running? Have you fettled the rtab in anyway?

I'm running clubsports and arbs on a fairly aggressive setup and I've got loads of grip at the rear, infact probably too much.

Also consider corner weighting, makes the car so much smoother once its been properly done with a geo, the guys I use are a porsche specialists and they were impressed with the road manners and ride compared to the porsches they do with a similar setup.

I know Beedub will say the same, once you properly sort the zed it really is very very good!

P. S. It'll never ride like a lotus it's twice the weight! :rofl:
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Z4M - Suspension Help

Post by RedUn » Wed May 09, 2018 12:15 am

InterlagosZ4MR wrote: Tue May 08, 2018 8:54 pm Thanks for all replies. Running OEM wheels with new Pilot Sports. I guess coilevers are the answer but that’s another £2.5k investment on top of the £1k I’ve just spent on the B12. As I mentioned, I’ve had the Z for 4 (nearly 5) years and have had Elises, Caterhams and numerous M3s... and just want it even 50% as compliant as any of those...
Answered these in the wrong order but something else that helps with the ride is spacers, they take the edge of the crashyness.
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Post by Pures3 » Wed May 09, 2018 12:19 am

Take a look at this old thread regarding RTABs. I’m putting the turners on mine - hope it sorts out the feeling of total lack of control on twisty B roads!

viewtopic.php?t=62834

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Post by gazpat » Wed May 09, 2018 11:34 am

Hi,
As per my previous posts on this subject (not sure how to link), Nitron coilovers all round specced for road use, standard (factory) ride height, full Geo set up by Centre Gravity (who know their stuff), job done. Not cheap I agree, but probably the best performance mod you'll ever make to this car....

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Post by MrPT » Thu May 10, 2018 9:26 pm

RedUn wrote: Wed May 09, 2018 12:11 am
MrPT wrote: Tue May 08, 2018 10:27 pm +1

It’s a fundamentally unsettling car to drive. How much of that is perceived due to the layout and how much is caused by the chassis and suspension set up, I’m not sure.

The KWs I have definitely sort out the crash/unrefined behaviour, but the rear is still very lively.
What geo are you running? Have you fettled the rtab in anyway?

I'm running clubsports and arbs on a fairly aggressive setup and I've got loads of grip at the rear, infact probably too much.

Also consider corner weighting, makes the car so much smoother once its been properly done with a geo, the guys I use are a porsche specialists and they were impressed with the road manners and ride compared to the porsches they do with a similar setup.

I know Beedub will say the same, once you properly sort the zed it really is very very good!

P. S. It'll never ride like a lotus it's twice the weight! :rofl:
Yeah. It needs higher spring rates and has less travel to work with than Norfolk’s finest. Especially at the rear.

Geo was stock but for a setup 1.5cm lower than I am currently running. Corner weighting was done and there’s a bit of an offset in suspension heights because of that. RTABs are visually ok but I’m going to do a refresh of all bushes soon, fit limiters and get the geo done to my own liking. I recently pulled the camber pins and went to max -ve (which has been great) but the front end is getting a bit woolly. ARB bushes in particular look pretty tired.

Don’t get me wrong, I love the way the car handles, but it doesn’t feel as composed as other sports cars I’ve driven. Spent about an hour of track time in a C63S recently and it came a lot closer to the Z4M for excitement than the Porsches I’ve driven. Really impressed by it. It’s that combo of slightly mad engine and difficulty putting the power down that’s so addictive, although to be fair it has 700Nm. :o
2008 Z4MC: heavy wheels | crap suspension | skittish rear end | wobbly engine | not enough induction noise | underwhelming turn in | inconsistent braking | lardy battery | chubby steering wheel
2006 Z4 2.5si: gone

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Post by RedUn » Fri May 11, 2018 12:09 pm

A mate had a c63, awesome car, properly rowdy aren't they :evil:

Like you say the geo probably won't help, the OEM geo gives a very dull feeling, be good to get that sorted out 8)

The front shouldn't be woolly at all once that's done, if it is somethings worn somewhere? Maybe the arb bushes like you say? I do recommend the h&r arbs mind, really tighten the car up and work well with the kws :thumbsup:
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Post by Nev » Fri May 11, 2018 2:44 pm

I've not that long ago fitted B6's with Eibachs all round and the ride is much better but still crashy going over any form of pothole, which to be fair are everywhere up north! Since my upgrade to the suspension, as all my corners were shot and in need of replacing, the car feels so much more planted on the road. Very good fun thrashing around the lake district recently!

I've been replacing bushings all over the place but the harshness I've found is now mainly at the rear. I've been messing around with the rear top mounts a bit. Changed them to poly bushes, but found them waaay too harsh so i've gone back to nearly OEM with Meyle HD top mounts. The tightness of the top nut on the rear top mounts seems to make quite a difference too. Too tight and its banging going over any stone in the road, too loose and its clanging a bit! As I said before, the roads up here are shite for it so its about getting a balance.
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Post by ph001 » Fri May 11, 2018 4:30 pm

Tyre pressure do make a big difference so I would definitely experiment taking them down as low as 30psi rear, 28psi front (if you haven't already).
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Post by autobahner » Fri May 11, 2018 10:14 pm

InterlagosZ4MR wrote: Tue May 08, 2018 8:54 pm Thanks for all replies. Running OEM wheels with new Pilot Sports. I guess coilevers are the answer but that’s another £2.5k investment on top of the £1k I’ve just spent on the B12. As I mentioned, I’ve had the Z for 4 (nearly 5) years and have had Elises, Caterhams and numerous M3s... and just want it even 50% as compliant as any of those...
I've had 3 e46 M3 and all were far nicer to drive than the Z4M I had for a short time. Handling as you described and I felt completely detached from the road, the opposite to the M3. Sold and looking for another M3 :wink:

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