First Damper / Springs mod question

D

DC Z4

Member
 UK S
Hi everyone,

I was looking at a thread on the pistonheads forum about this era of Z4Ms and how to improve handling (think it was mixed responses from coupe and roadster owners).

Consensus was that bilstein b16s or KW street coilovers did wonders for improving turn in and rebound. Or that just fitting some eibach pro springs made a huge difference.

Has anyone fitted any of these to their e85 Z4MR and can share the difference? Thanks
 
Sometimes the hardest part is just confirming the exact spec you need. I’ve been using AUTODOC MARKETPLACE recently to cross-check part numbers and see what brands actually make the part.
 
KWV3 coilovers are likely the best option for the M, provided they are set up correctly.

At this age, the original struts will almost certainly have lost their gas pressure and require replacement. OEM parts are no longer available, and the Bilstein B6 kit serves as a direct replacement for the original setup.

Although the Z4M did not receive strong reviews initially, Its 20 year ago and most cant remember what a fresh car feels like. Any car on fresh dampers will see a significant improvement. The issue with the original Sachs struts is that they tend to degrade by around 40k miles or 5-6 years old, often losing gas pressure and therefore damping performance. This can leave the springs doing most of the work, which contributes to their reputation for snapping.

Ultimately, the best option depends on how you intend to use the car, whether primarily for track or road driving.

For example, I previously ran H&R springs on standard struts with a 30–35mm drop. While the car looked great, the ride quality suffered, with frequent bottoming out. A key limitation is the rear suspension travel, which can make the car feel unsettled. Many aftermarket solutions address this issue.

Personally, I plan to install the Bilstein B6 kit, as it is a straightforward, plug-and-play upgrade that offers improved performance over the original equipment without the need for extensive setup.
 
I swapped to B16 PSS10 at just over 100k miles - and I've had it since 9000 miles.

I left it that late because they weren't physically broken - and I've never had a snapped spring - the reasons being 1) it was now out of BMW extended warranty; 2) I wanted to do some other mods for track days; 3) I got a better price than I could for the KWs; 4) they were/are easier to adjust when I get to the track; 5) they didn't have reports of fouling on anything.

This is on a Z4MC though, which is stiffer than a Z4MR, but even on their stiffest setting they behave much better than OE suspension (at any point in the OE suspension life).
 
I've only every ran BCs due to adjustment at the price point. Had good success on the non-M, pretty bad on the M. I got stiffer spring rates and the setup simply cannot settle fast enough on public roads. Feels like it skips over bumps.

To be honest, unless you need adjustability for tracking, I think the eibach+koni or Bilstein B12 are solid setups. Will KW V3 or Ohlins be better? Yes, but I don't know if they're worth 2-3x the price, especially if you're not tracking the car and don't need all that adjustment.
 
tomscott said:
KWV3 coilovers are likely the best option for the M, provided they are set up correctly.

At this age, the original struts will almost certainly have lost their gas pressure and require replacement. OEM parts are no longer available, and the Bilstein B6 kit serves as a direct replacement for the original setup.

Although the Z4M did not receive strong reviews initially, Its 20 year ago and most cant remember what a fresh car feels like. Any car on fresh dampers will see a significant improvement. The issue with the original Sachs struts is that they tend to degrade by around 40k miles or 5-6 years old, often losing gas pressure and therefore damping performance. This can leave the springs doing most of the work, which contributes to their reputation for snapping.

Ultimately, the best option depends on how you intend to use the car, whether primarily for track or road driving.

For example, I previously ran H&R springs on standard struts with a 30–35mm drop. While the car looked great, the ride quality suffered, with frequent bottoming out. A key limitation is the rear suspension travel, which can make the car feel unsettled. Many aftermarket solutions address this issue.

Personally, I plan to install the Bilstein B6 kit, as it is a straightforward, plug-and-play upgrade that offers improved performance over the original equipment without the need for extensive setup.
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Thanks Tom that's some good history I didn't know.

I'm probably going for a fast-ish road setup, one that's easy to cruise long miles into France on a summer road trip. I'd also like to try to address any rebound making the car feel floaty when pushing on - I owned an m140 and definitely remember that sensation being unsettling. If I can achieve both those goals without the car bottoming out or needing an L6 disc realignment in my spine when I hit a pothole I'll be made up

I plan to try out one track day later in the year too, but I'm not going to set the car up just for one day :)
 
Rsipad said:
I've only every ran BCs due to adjustment at the price point. Had good success on the non-M, pretty bad on the M. I got stiffer spring rates and the setup simply cannot settle fast enough on public roads. Feels like it skips over bumps.

To be honest, unless you need adjustability for tracking, I think the eibach+koni or Bilstein B12 are solid setups. Will KW V3 or Ohlins be better? Yes, but I don't know if they're worth 2-3x the price, especially if you're not tracking the car and don't need all that adjustment.
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Can you tell me what you mean by the eibach+koni setup please? Sorry if that's a silly question - it's all new stuff to me.

I think those would be lowering springs? I might struggle with those with the state of UK roads these days!
 
tomscott said:
For example, I previously ran H&R springs on standard struts with a 30–35mm drop. While the car looked great, the ride quality suffered, with frequent bottoming out.
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I can relate to that as my car same fitted with H & R coil-overs and the ride is really firm. It was slammed when I bought it, but getting them up as high as they will go meant it didn't scrape over speed bumps!

But they seem a bit pointless as only the ride height it adjustable. I've left them on for now as they were only a few months old, although I did get a quote for supplying and fitting KWV3s out of curiosity - it was almost £3K.
 
DC Z4 said:
Can you tell me what you mean by the eibach+koni setup please? Sorry if that's a silly question - it's all new stuff to me.

I think those would be lowering springs? I might struggle with those with the state of UK roads these days!
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Yep what Koni shocks are available, aside from GCs?
 
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If I change mine that's the route I would go as well. :thumbsup:

I know a couple of MC owners who fitted Eibach springs and disliked them enough to go back to OE!
 
Mr Tidy said:
If I change mine that's the route I would go as well. :thumbsup:

I know a couple of MC owners who fitted Eibach springs and disliked them enough to go back to OE!
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Oh wow

Eibach springs are one of the classic recommendations for clio 182's (my old car) and m140s (my old old car) IIRC so good to know if thats definitely not the case for the Z4m
 
It's not that it's not the case but lowering the car makes it more crashy. I survived with my H&Rs but I was 23 when I had them don't think my back would deal with it now. Depends what you want out of the car.
 
I once drove an M roady with Eibach springs and immediately thought if I buy this car the springs are going in the skip, too low, skittish, too firm, horrible ride, which is a surprise as I have them on my MK2 MR2 and they’re superb on that.

Anyhoo, if budget allows personally I’d go KWV3 street coilovers, I have these on my M roady, they adjust for bump and rebound along with adjustable ride height, set up properly and they transform an M, make it so much nicer on rough roads, cornering they’re progressive so tighten up nicely, no harshness at all.

Best of luck whichever way you go.
 
john-e89 said:
I once drove an M roady with Eibach springs and immediately thought if I buy this car the springs are going in the skip, too low, skittish, too firm, horrible ride, which is a surprise as I have them on my MK2 MR2 and they’re superb on that.

Anyhoo, if budget allows personally I’d go KWV3 street coilovers, I have these on my M roady, they adjust for bump and rebound along with adjustable ride height, set up properly and they transform an M, make it so much nicer on rough roads, cornering they’re progressive so tighten up nicely, no harshness at all.

Best of luck whichever way you go.
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Interested to know what settings you put them on for road :)

And if you take it on track do you make any changes?

Thanks!
 
Cheers :)

I watched a video of someone fitting nitrons to an m140 last night - they look very nice, around the KW price point.

Sent me down a rabbit hole of spring rates on the bmw cutters forum...
 
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