What coilover kit do you have (Poll)

[exdos]

The problem with the Z4M's OEM suspension, particularly the E86M, is the rear springs are way too stiff at 19mm thick and the front springs are way too soft at 11mm thick. Any of the aftermarket adjustable suspensions which have rear springs of around 16mm thick and front springs of around 14mm thick will be a considerable improvement on OEM , especially when you can also adjust the damper settings to suit your purpose. For a "general purpose" Z4M that set a few trackdays, KWV3 or Bilstein B16, with stainless steel dampers, will be ideal.

I don't think the spring wire size is thàt thick

See my posting here: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=38918&hilit=suspension&start=30 dated Thu Jun 28, 2012 6:48 pm with the photo to prove it. oke:

 

[Mister T]

The problem with the Z4M's OEM suspension, particularly the E86M, is the rear springs are way too stiff at 19mm thick and the front springs are way too soft at 11mm thick. Any of the aftermarket adjustable suspensions which have rear springs of around 16mm thick and front springs of around 14mm thick will be a considerable improvement on OEM , especially when you can also adjust the damper settings to suit your purpose. For a "general purpose" Z4M that set a few trackdays, KWV3 or Bilstein B16, with stainless steel dampers, will be ideal.

I don't think the spring wire size is thàt thick

See my posting here: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=38918&hilit=suspension&start=30 dated Thu Jun 28, 2012 6:48 pm with the photo to prove it. oke:

On my Coupe they were 14mm front, 18mm rear (at the thickest point).

 

[GuidoK]

See my posting here: http://www.z4-forum.com/forum/viewtopic.php?f=9&t=38918&hilit=suspension&start=30 dated Thu Jun 28, 2012 6:48 pm with the photo to prove it. oke:

I was talking about the KW kits for the e85 platfrom, so for example for the rear kw2008 spring
The numbers I gave are from the Tüv teilgutachten for the z4/z4m kits, which is an official state document, so if they would sell different rates for those kits, they'd be comitting a huge economical crime in germany.
so....this is the official data for the rear spring 2008:
drahtstärke: 12.2mm
Außendurchmesser oben 86.0mm
mitte 126.0mm
unten 72.0mm
Länge 180.0mm
Windungszahl 7
Federform Tonne ende geschliffen (oben)

The front progressive spring is a bit thicker (13.1), the linear springs are all thinner. I'm not going to write all the data down, it's on the interwebs.
But in the end it's the compression constan that counts and not the thickness. The thickness (alone) is not an indication of the compression constant. A thinner wire diameter can easily have a larger compression constant due to design.

 

[exdos]

It's over 3.5 years ago since I measured. I'll have to dig the OEM kit out some time and have another look. I remember though, at the time comparing the thickness of the OEM Z4MC rear springs against an OEM rear ARB off my Z3MC and they were almost the same thickness!

 

[Fishy Dave]

Really interesting stuff all, thanks Guido for your V3 and Clubsport info. : )
I'd like to hear from those of you using coilovers how easy are the rear dampers to adjust? Much as I hated the Elise I had before the Z4 the Nitrons it wore were excellent and really easy to adjust with a knob on the bottom of the damper body, taking seconds at the track without needing to jack the car up or remove wheels.

 

[GuidoK]

The kw v3 and clubsport both have a knob at the bottom and one at the top. (bottom for rebound, top for compression (from mind)).
The older style had for the rear a top adjustment screw, so you hand to drill a small hole in the boot lining to reach that, the newer ones have a set dial inside the wheel arch.
Both are a pain, unless you have a coupe, then the old style is better.
But there are also kw old style variants that you have to try and put a really small diameter hex key in a hole. So not everything old is good imho.

 

[mmm-five]

I can do my PSS10s from the ground, as it's just a clockwise or anti-clockwise click on the knob at the bottom of the strut.

Can't easily see what number is on there currently though - but a torch and full lock lets me see the fronts, and a bit of neck twisting lets me see the rears.

Although I've only adjusted them once, and that was to move the fronts from 6 to 7. Seems to be a good enough compromise between road & track manners (and I definitely don't blame the suspension settings for my accident).

 

[MACK]

I have KW V3 on my Z3MC, which are similar to Clubsports for the Z4M and I also have AC Schnitzer Racing suspension on my Z4MC, I've done hundreds of laps around The Ring in both cars and they are both great suspension systems and way better than OEM for both cars.

The problem with the Z4M's OEM suspension, particularly the E86M, is the rear springs are way too stiff at 19mm thick and the front springs are way too soft at 11mm thick. Any of the aftermarket adjustable suspensions which have rear springs of around 16mm thick and front springs of around 14mm thick will be a considerable improvement on OEM , especially when you can also adjust the damper settings to suit your purpose. For a "general purpose" Z4M that set a few trackdays, KWV3 or Bilstein B16, with stainless steel dampers, will be ideal.

Hi, not wishing to hijack the thread but do you (or anyone else) have similar info on the thickness of non M OEM springs, I've got a 3.0i
Also has anyone measured their bilstein pro kit?

thanks

 

[tertius]

Really interesting stuff all, thanks Guido for your V3 and Clubsport info. : )
I'd like to hear from those of you using coilovers how easy are the rear dampers to adjust? Much as I hated the Elise I had before the Z4 the Nitrons it wore were excellent and really easy to adjust with a knob on the bottom of the damper body, taking seconds at the track without needing to jack the car up or remove wheels.

I also had Nitrons on my Elise, and the Intrax I have now on the Z4 are similar - single knob at the bottom of the damper, very easy to do in the pits, though with many more clicks than the Nitrons had.

I have had (different) cars with KWs, Nitrons and now Intrax - overall my favourite is definitely Nitron.

 

[TomK]

I've heard a lot of good things about Nitron. It's also nice to have them rebuilt in oxford rather than sending Intrax back to Holland.
My suspension will be being done this year and Nitron is high on the list, I'm just really really tempted to go intrax 1k2 again with ARC control (supposedly amazing, and avoids issues with thicker ARBs), although that means a £3.5k ish bill Do your intrax have the ARC tertius?

 

[tertius]

I've heard a lot of good things about Nitron. It's also nice to have them rebuilt in oxford rather than sending Intrax back to Holland.
My suspension will be being done this year and Nitron is high on the list, I'm just really really tempted to go intrax 1k2 again with ARC control (supposedly amazing, and avoids issues with thicker ARBs), although that means a £3.5k ish bill Do your intrax have the ARC tertius?

No, regular 1K2 with barrel spring on the rear.

 

[Beedub]

i tried nitron and they wouldnt offer me a rear barrel spring/ separate spring to damper after discontinuing the stock type setup for sale when i last checked, not sure if that has now changed.

After these years still totally satisfied with my clubsport setup, bmw choses use same dampers for their m3 GTS model too which lends well to kw as a top class supplier. Adjusting them is a pain in the ass, and the ride is rock solid tbh, BUT after owning the fiesta st which is really hard from factory and linear sprung, the clubsports are much much stiffer but really have a decent level of control to them, something i hadn't really noticed until my hard riding ST which still leans heavily and crashes around, the z4 sees none of this and has a control to the way it moves around that really feels special. These dampers brought my z4m alive! They even manage to look totally gorgeous too!

 

[ChawenHalo]

OP, like some others (BadPritt, MMM5 from memory) I have a full Bilstein setup and am very happy with them and of course will be biased towards my choice. My choice was however very researched and guides by my requirements and goals with the car long term. I use my car mostly on road on all conditions and difficult roads with 3 Track Days per year maybe on average. I wanted a "fast road" set up that would bring more feel to the steering and reduce understeer on the track. Lastly my priority was to have a safe setup on the limit (of both adhesion and my lack of talent) and for this reason I had the whole chassis installed by a seasoned and recognised racing outfit (recommended by BMW). There were a whole bunch of stuff they did other than the coilovers and having had it for a few years now, I'm delighted with it. It is a big budget though, and it will strongly change your car.

I went for Bilstein for 3 reasons. Kit is made specifically and tested for the car by the manufacturer and used by many BMW and Porsche racing teams for both track AND road racing for many many years. They spat their dummies put when I asked about KW saying it would come to pieces and sag within a few 1000 km. I'm sure plenty would disagree with this later point and frankly I could not comment seriously other than to annoy KW users. oke:

Unlike some I do like the OEM setup but do think it is worth buying higher spec tires for Track Days and developing ones driving skills first, it is after all a heavy car for track days...

Some setups like ACSchnitzer reportedly change the ride for the better overall and improve comfort whilst others are more track focused and require a lot of knowledge and practiced tuning. Most kits are generic, few are car specific and fewer are thoroughly tested. As the racing chaps told me the compromise with all the setups for road and track use is simple: for the road its never soft enough and for the track never hard enough. Bearing in mind this is at the extreme ends of the scale the in between for amateur users is just fine. My only provisio would be on a reputable professional install and geometry. We're not driving gods or raceteam professionals and its good to know your chassis is safe as well as competent. :driving:

 

[alanhasanicez4m]

Interesting comment on KWs, I havn't heard that at all before. My car is mostly for track days these days. However I do need to get to the track in it too and am planning Nurburgring this year and plan to arrive with all my teeth still in my head.

I'm currently on pss tyres but do want to get a new set of wheels so I can have a more track orientated set and keep the pss for road / winter use.

As for driver skills, I couldn't agree more, I get instruction at every event I do. Well worth it.

 

[veilside85]

regarding the kw v3 do you have to run spacers with the standard m wheels and tyres ?

 

[MrPT]

regarding the kw v3 do you have to run spacers with the standard m wheels and tyres ?

Yes, at least 5mm on the front; potentially 10mm, depending on the shape of the tyre. This is because of the progressive (conical) springs. The CS doesn't suffer the same issue.

You can also fit linear springs on the V3, but if that's the case you might as well buy the CS in the first place.

 

[veilside85]

regarding the kw v3 do you have to run spacers with the standard m wheels and tyres ?

Yes, at least 5mm on the front; potentially 10mm, depending on the shape of the tyre. This is because of the progressive (conical) springs. The CS doesn't suffer the same issue.

You can also fit linear springs on the V3, but if that's the case you might as well buy the CS in the first place.

Just normal tyre size.

Is it not a bad design if it don't suit standard wheels tyre size???

 

[MrPT]

regarding the kw v3 do you have to run spacers with the standard m wheels and tyres ?

Yes, at least 5mm on the front; potentially 10mm, depending on the shape of the tyre. This is because of the progressive (conical) springs. The CS doesn't suffer the same issue.

You can also fit linear springs on the V3, but if that's the case you might as well buy the CS in the first place.

Just normal tyre size.

Is it not a bad design if it don't suit standard wheels tyre size???

Certainly a design oversight, yeah. Perhaps the result of testing on non-OEM wheels or gel settings. I do find the ride pretty good, so I think there's a case for getting the V3 over the CS if you don't do much track work. Doubt there is much between them unless you do a back to back at their limits.

 

[NavZ]

Is it not a bad design if it don't suit standard wheels tyre size???

Fair point…
In their defence people who can afford to spend that much on coils probably have a few other mods.
Def not their brightest moment though :rofl: