Z4M ride quality improvement

[Dudi]

Hi guys,

new user from the UK here. I've had the Z4M as a daily driver for 2 years but recently my route has changed to one with particularly bad roads which is making the drive very bouncy/crashy.

The car has only 30k miles so all the bushings etc are nice and tight and I had Bilstein B12 kit (shocks and Eibach springs) placed 6k miles ago which got rid of some of the slop from the OEM but I'd like to improve the quality of the ride especially small bump sensitivity some more.

Could I get some recommendations? KW V3? Other coilover kits with road specific dampening?

Not looking for a limousine comfort but my other car is a Nissan GTR which actually rides bumps better than the Z4M.

Cheers.

[Mirko]

Hi and welcome.

I have Kw v3s and the ride quality improved greatly over stock. One place I noticed it the most was when doing a tail out slide. With stock suspension it would snap back but with the v3's it was a smoother transition. I don't remember much anymore of how stock felt as it's been many years but I do know that v3s soak up bumps better and the car transitions smoother. obviously also depends on how you set them up but general consensus is that they are better than stock.

[CTMP4me]

Wait 2 more months and I'll have a review of my setup from Fat Cat Motorsports (http://www.fatcatmotorsports.com/) for you. I have full confidence it will be near-magic, even with my "max track grip" design goal rather than a comfort-first setup.

If you want better ride quality compared to OEM, you'll need to find a setup that's not overdamped in rebound as many stock and aftermarket setups are (i.e. following a bump, wheel doesn't come back down as quickly and the suspension just "jacks down"). This is something best seen on a shock dyno plot, which are hard to come by unless you're getting your dampers custom valved.

For comfort, I'd go with a softly sprung setup (275-300 lb-in front springs, sub-450-500 lb-in rear springs if you're staying with stock spring location), maximum possible suspension travel, and dampers that work with those spring rates.

[GuidoK]

I also have a kw v3 set (albeit on a non m but valving is the same) but I think they're fairly stiff... (much stiffer than oem)
Great for cornering though.

Usually coilovers are stiffer than OEM as they are a performance product. That almost always means stiffer

Do you drive on runflats or 19" wheels? I think with wheels&tyres the biggest gains on comfort can be made.

[Dudi]

I was on Pilot Super Sports with standard Z4M wheels but have swapped to Pilot Sport 3's which has a slightly more forgiving ride due to more flexible sidewalls.

It's not so much about the high speed comfort. If anything the high speed compliance is much better with B12 than OEM. It's more the around town low to medium speed small bump sensitivity.

I read that the V3's have quite good small bump sensitivity and the adjustability would obviously be useful. I think the best coilovers I have personally experienced for road comfort were Ohlins DFV, shame they don't make them for this platform.

[racerbruce]

Originally Posted by Dudi

I was on Pilot Super Sports with standard Z4M wheels but have swapped to Pilot Sport 3's which has a slightly more forgiving ride due to more flexible sidewalls.

It's not so much about the high speed comfort. If anything the high speed compliance is much better with B12 than OEM. It's more the around town low to medium speed small bump sensitivity.

I read that the V3's have quite good small bump sensitivity and the adjustability would obviously be useful. I think the best coilovers I have personally experienced for road comfort were Ohlins DFV, shame they don't make them for this platform.

Greetings from Seattle;
My Bilstein B12's and Eibach Pro-Kit Springs arrived yesterday. Installation is scheduled later this month. The B12's are a fixed lowering amount of 20mm front and 10mm rear. What was your experience with the advertised lowering amount - was it appx this amount - any tire/wheel clearance issues - was your wheel alignment able to achieve the front amber OEM spec - or did you have to installed additional camber kits to achieve proper camber specs? Great to hear that performance handling improved - looking forward to your updates - regards.

[Dudi]

The lowering was as stated - 20mm 10mm with no rubbing. OEM geometry was achieved on a Hunter machine by the garage who fitted the suspension with no issues. For fast road driving (I haven't taken this car on track) the suspension really transformed the car from brake dive to pitching over undulations.

Hence why I'm a little cautious to change again unless it can improve the low speed ride. The B12 is a really great kit and would highly recommend it.

[racerbruce]

Thank you Dudi -
I'm replacing the front control arms and upgrading them, and replacing the front control arm bushings and guide supports:

T#21492 - 31122341828 - Genuine BMW Front Control Arm - Right - E46, Z4 - ZHP/Sport Upgrade - Genuine BMW - BMWGenuine BMW Front Control Arm - Right - E46, Z4 - ZHP/Sport Upgrade
T#: 21492

1

$305.95

$305.95
T#54503 - 31308040203 - Genuine BMW Guide Support - 31308040203 - E85 - Genuine BMW - Genuine BMW Guide Support - 31308040203 - E85

[Manxman1950]

Originally Posted by CTMP4me

Wait 2 more months and I'll have a review of my setup from Fat Cat Motorsports (http://www.fatcatmotorsports.com/) for you. I have full confidence it will be near-magic, even with my "max track grip" design goal rather than a comfort-first setup.

If you want better ride quality compared to OEM, you'll need to find a setup that's not overdamped in rebound as many stock and aftermarket setups are (i.e. following a bump, wheel doesn't come back down as quickly and the suspension just "jacks down"). This is something best seen on a shock dyno plot, which are hard to come by unless you're getting your dampers custom valved.

For comfort, I'd go with a softly sprung setup (275-300 lb-in front springs, sub-450-500 lb-in rear springs if you're staying with stock spring location), maximum possible suspension travel, and dampers that work with those spring rates.

I'm very interested in how this works out for you. I have spoken to Shaikh a couple of times and his approach is very persuasive.

[Dudi]

Originally Posted by Mirko

Hi and welcome.

I have Kw v3s and the ride quality improved greatly over stock. One place I noticed it the most was when doing a tail out slide. With stock suspension it would snap back but with the v3's it was a smoother transition. I don't remember much anymore of how stock felt as it's been many years but I do know that v3s soak up bumps better and the car transitions smoother. obviously also depends on how you set them up but general consensus is that they are better than stock.

Hi Mirko,

could you tell me whether you have had to cut any internal trim to access the rear upper adjusters.

From what I can see KW have revised the adjuster wheels and locations but can't get a certain answer as to whether they have for the Z4M application.

I'm pretty much set on going for them so will be ordering in the next few days.

[Digs]

Originally Posted by Dudi

Hi Mirko,

could you tell me whether you have had to cut any internal trim to access the rear upper adjusters.

From what I can see KW have revised the adjuster wheels and locations but can't get a certain answer as to whether they have for the Z4M application.

I'm pretty much set on going for them so will be ordering in the next few days.

Dudi,
I purchased and installed KWV3 in August 2015 and didn't need to cut any internal trim to access the adjusters, not sure if they've changed since then ?Really happy with the ride quality especially since I'm lowered, although I think lighter wheels improved small bump comfort quite a bit too. I don't think these Zeds will ever be super comfy since we're sitting on top of the rear axle.

[CTMP4me]

Originally Posted by Manxman1950

I'm very interested in how this works out for you. I have spoken to Shaikh a couple of times and his approach is very persuasive.

To revive this - Fat Cat dampers just arrived this afternoon. I should have them on by the weekend and post impressions on ride quality then.

[kaybat]

Originally Posted by Dudi

Hi Mirko,

could you tell me whether you have had to cut any internal trim to access the rear upper adjusters.

From what I can see KW have revised the adjuster wheels and locations but can't get a certain answer as to whether they have for the Z4M application.

I'm pretty much set on going for them so will be ordering in the next few days.

There is a old thread(i think on here)where a roadster owner cutaway an opening for rear shock adjustment(s)

I'll see if i can find it.

[Dudi]

Just to bump this thread and get further opinion.

Ordered a set of V3's but the supplier sent a set for a normal Z4 not a Z4M. In the meantime a set of KW Clubsport have come available for less money than I will be paying for V3's.

Any daily drivers on Clubsports out there? Will the ride be significantly firmer than V3's?

[CTMP4me]

Originally Posted by CTMP4me

To revive this - Fat Cat dampers just arrived this afternoon. I should have them on by the weekend and post impressions on ride quality then.

Update - I've put the Fat Cat Motorsports setup through a thorough test on the road and on track at CTMP/Mosport.
I asked for a soft, "max grip" track day set up to be used with RE71R / streetable R-comp tires (but no significant downforce) and Shaikh at FCM more than delivered.

The Z4M now much more composed - more grip everywhere on the exact same set of tires, car is much less upset by track curbs and on-road potholes, way less harshness from highway expansion joints / sharp bumps, even with monoball rear shock mounts and race camber plates.

The suspension also recovers faster from successive bumps / dips, so even as the speeds increase, it just keeps on soaking up road imperfections.

Overall, I'm very happy with the setup so far as it achieves massively improved comfort and ride quality despite being designed primarily to improve track grip.

The spec: FCM-revalved non-adjustable Bilsteins with flat ride / ripple reducer / FCM's "kerb blow off" tech (started with the off-the-shelf H&R coilover kit), 336 / 616 lb-in F/R linear Swift springs, Vorshlag race camber plates, RE monoball rear shock mounts.

[Manxman1950]

Originally Posted by CTMP4me

Update - I've put the Fat Cat Motorsports setup through a thorough test on the road and on track at CTMP/Mosport.
I asked for a soft, "max grip" track day set up to be used with RE71R / streetable R-comp tires (but no significant downforce) and Shaikh at FCM more than delivered.

The Z4M now much more composed - more grip everywhere on the exact same set of tires, car is much less upset by track curbs and on-road potholes, way less harshness from highway expansion joints / sharp bumps, even with monoball rear shock mounts and race camber plates.

The suspension also recovers faster from successive bumps / dips, so even as the speeds increase, it just keeps on soaking up road imperfections.

Overall, I'm very happy with the setup so far as it achieves massively improved comfort and ride quality despite being designed primarily to improve track grip.

The spec: FCM-revalved non-adjustable Bilsteins with flat ride / ripple reducer / FCM's "kerb blow off" tech (started with the off-the-shelf H&R coilover kit), 336 / 616 lb-in F/R linear Swift springs, Vorshlag race camber plates, RE monoball rear shock mounts.

How does your ride height compare with OEM? Did Shaikh suggest the spring rates?
I am seriously considering an FCM setup for my roadster - would you mind PM-ing me with approx all-in cost, for comparison purposes.
Thanks

Stuart

[CTMP4me]

Originally Posted by Manxman1950

How does your ride height compare with OEM? Did Shaikh suggest the spring rates?
I am seriously considering an FCM setup for my roadster - would you mind PM-ing me with approx all-in cost, for comparison purposes.

PM Sent.

I kept ride height close to OEM to better manage speed bumps, random troughs / ledges / potholes, and badly graded approaches.

I've been very pleased with my setup so far, it's been a no-compromise improvement in both grip level and comfort.

[ZeD4Mr]

Originally Posted by CTMP4me

PM Sent.

I kept ride height close to OEM to better manage speed bumps, random troughs / ledges / potholes, and badly graded approaches.

I've been very pleased with my setup so far, it's been a no-compromise improvement in both grip level and comfort.

So there isn't any rebound or ride height adjustments correct? Can you also pm me cost and availability as well?

TIA,