E85 M- views please on suspension

bigwinn

bigwinn

Elite
 Lincoln UK
Site Supporter
Hi all

I think I've made it very clear that I love my M: its peak Z for me.

However I'm in the dangerous mid-ground now of having a great car that doesn't want for much. It flew through its MOT and I've done most big jobs/retrofitting leaving: suspension!

The car is on stock shocks which are 18 years old and eibach springs. No signs of leakage and 51k miles, I am under no illusion they are probably at the end of their life, but handling is 'good'. Now I have nothing to benchmark on, but I know what a sorted 3.0si feels like on new running gear and my M isn't far off that.

It doesn't get tracked or driven too heartily (yeah right) so I would like folks views on what to do. I don't want a hard crash ride at all- that's the thing I've been most impressed with the standard/eibach set up I have is how well it rides.

Stay as is
Opt for like for like shocks from BMW (long lead time)
Go the Bilstien route
Go coilovers- I nearly made an offer on these: https://z4-forum.com/threads/ast-5100-fast-road-coilovers-for-e85-e86-z4m-mint.153132/

Tell me your thoughts, I'm all ears.

Stuart
 
It's a slippery slope. While the Z4MR handles okay—mine has 90k miles now—I also owned a Z4M Coupe back in 2011, and in comparison, the Roadster feels noticeably less composed. It's not really a question of chassis rigidity, but rather that the suspension just doesn't work as the shocks are past their best. The steering rack in the Roadster doesn’t help either—it feels more disconnected.

The Bilstein kit is a decent OE-style replacement, especially with some minor tweaks to the rear setup to reduce that nervous, skittish feel. One thing I’ve noticed (and seen mentioned often) is that Bilstein components tend to rust quickly and get grubby, so it’s worth sealing them before installation. That said, it's probably the best budget-friendly option available.

I’ve been researching this for a couple of years, and the KW V3 kit consistently stands out as the best choice. I just haven’t been able to justify the cost yet—but realistically, that’s the setup to aim for.
 
For road, and coilovers, I'd stick to KW V3 or Bilstein B16 PSS10 (I'm very happy with mine).

I ended up with the B16s, and didn't go with the KW V3 (or the Clubsport) because 1) there were reports that the original versions were difficult to adjust (i.e. requiring trim adjustments inside the boot); 2) they hit/caught/interfered with something on the front axle (roll bar or steering knuckle); 3) I could have a higher ride height with the Bilsteins (as I didn't want any more than 10mm of lowering).

But I believe KW have modified them since.
 
Appreciate that- I’m the same looking at coilovers I have a view of old that they are a bit boy racer which I think I need to get over

When we installed the kit on ponds Ferrari they were very good quality: but no evidence to how it did or didn’t improve handling as yet

Bilsteins are the safe option albeit I hear they are very hard
 
bigwinn said:
Bilsteins are the safe option albeit I hear they are very hard
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I'd not put on any of the cheap, ebay, boy-racer kits with 100mm lowering - of course some of them can be a budget option, but I'd not put much trust in a budget holding up to the levelof abuse I give mine ;)

No experience in the Z4M of anything other than OE BMW and the B16s (which were fitted at about 100,000 miles)...although I think the cheaper, non-coilover Bilstein spring & damper kits can affect the ride somewhat.

The benefit of coilovers is that they're adjustable, so I just set mine up differently for different purposes, i.e. 2-3 clicks for commuting, 3-5 clicks for British hoons; 6-8 clicks for trips to the Nurburgring; 8-10 clicks for most UK tracks. Even on 10 I find it much more comfortable/controllable than OE suspension - and it means I could (with help of thicker ARBs and Vibra-Techics engine mounts) remove the twitchiness of the standard, incorrectly weighted (in my opinion) OE suspension.

Although, just realised you're asking about the Roadster, so I believe the same OE suspension on that worked better because it's not as stiff as the Coupe, so made it inherently less snappy.
 
Some folks dismiss BC because they're cheap and made in Taiwan, but I've had good results on my MR with an entry-level BR set with 6 kgs F / 10 kgs R spring rates. BC now offers a default rate of 5/8 which will be more compliant still.

I've not tried Bilstein B16 on a Z4 but had them on an Impreza where they worked well. For the Z4MR the B16 spring rates are 7/10 which are sensible for the road.

Lots of good reviews for Eibach springs and KW but the lack of published spring rates for these products puts me off, as well as the drop in ride height (OEM is low enough).
 
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I ran 4 setups on mine, OEM, OEM dampers and Eibach springs, then added H&R ARBs and RTABs and then added KWs, club sports as I prefer linear springs.

Basic view is OEM is complete crap, hence the bad reviews for the car at the time, this was on a 16k mile car a long time ago so it wasn't worn parts, it just handles bad for a sports car in my view.

The springs and arbs really helped but for a 340bhp car I'd say not enough to push on properly.

Adding the KWs and the rest of the gear transforms the car. I've been changing suspension on cars forever (I'm an addict, all my cars have adjustable setups) and it was the biggest transformation of them all.

I've been running KWs for 20 years on all different cars, in my view for the money they are the best, reliable, last well and more importantly, really well damped due to the twin tube design.

Long story short, spend the money, make it right, worth it:thumbsup:
 
RedUn said:
I ran 4 setups on mine, OEM, OEM dampers and Eibach springs, then added H&R ARBs and RTABs and then added KWs, club sports as I prefer linear springs.

Basic view is OEM is complete crap, hence the bad reviews for the car at the time, this was on a 16k mile car a long time ago so it wasn't worn parts, it just handles bad for a sports car in my view.

The springs and arbs really helped but for a 340bhp car I'd say not enough to push on properly.

Adding the KWs and the rest of the gear transforms the car. I've been changing suspension on cars forever (I'm an addict, all my cars have adjustable setups) and it was the biggest transformation of them all.

I've been running KWs for 20 years on all different cars, in my view for the money they are the best, reliable, last well and more importantly, really well damped due to the twin tube design.

Long story short, spend the money, make it right, worth it:thumbsup:
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Sage advice

Do it once do it best
 
My car had H & R coil-overs fitted when I got it. as they were less than 6 months old it seemed a bit extravagant replacing them but I really should have done.

They are only adjustable for height, not compression or rebound, so the springs are pretty short and to avoid bottoming they are very stiff so the ride can get crashy. I'd imagine other coil-overs would be similar unless you go for broke with a fully adjustable set-up like KW V3, although I got quoted the best part of £3K to supply and fit a set!

I know a couple of owners haven't liked Eibach springs on the front of their cars, to the extent they have removed them and gone back to standard.

I really ought to make a decision, but don't want to make the wrong one. :rolleyes:
 
I know I’m in the minority here but I can’t stand anything Bilstien other than the B4. I’ve tried it on multiple cars (my own included) and they rode like sh*t if the road wasn’t smooth as glass. It didn’t matter if they were paired with Eibach “matched” springs or any other brand, I always found the ride to be jarring. For street application, I’ll take Koni’s over Bilstein any day.
 
I’ve heard other Z4M owners rave about the KW v3 on here.

@tomscott what product should op (and maybe me!) seal are dampers with? Cheers
 
RMB said:
I’ve heard other Z4M owners rave about the KW v3 on here.

@tomscott what product should op (and maybe me!) seal are dampers with? Cheers
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KW’s are nice but v3 is overkill for non-tracked car imo. Me personally, if OP was content with the aesthetics of the OE ride height, I would just refresh the factory suspension with new B4 shocks, FCABs, tie rods, end links, RTAB, trailing arm bushings. And if you want to improve handling, add some camber washers and front CSL sway. A factory refresh with few small tweaks can make a big difference. I’d only consider shocks/springs or coilovers if OP wanted to lower the car, but that opens up another can of worms (e.g. potential wheel rub).

FWIW I never understood when anyone complained about the factory handling as being poor. You’d have to push the car to the limit to even start noticing any deficiency, which is super dangerous on public roads. I only noticed understeer initially during auto-x and a lot of that could’ve been dialed out with camber & square tires.

If anything, my only complaint is the factory ride was tad harsh. Yes, a 987 Cayman feels more neutral while compliant but a) mid-engine and b) PASM costs $4k to replace. But Z4 M being described as poor handling? Not sure about that. For 90% of time it’s perfect. If you want to address the remaining 10%, like I said take a look at Koni Sports.
 
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I have the V3s. They are very good once you are up to speed but fidgety around town - same as most other aftermarket options for this car and reminiscent of the more hardcore varieties of 911s, clios/meganes etc. Chances are that any friends/family you give a lift to will think that the ride is terrible!

But, if you can live with that and the fact that you are sat over the rear axle of a 1500kg car (so it is never going to feel like an Elise or A110), then they are excellent. You can hit fairly gnarly B road stuff at a decent pace and the car will settle very quickly - doesn’t exactly feel pleasant, but for sure not a trait the stock car is known for. Bottomming out is still something to be monitored, as is rear springs binding once the coating wears off (both things sound similar - bang!).

The stainless construction is also a big plus vs cheaper options, the springs are inexpensive (vs a strip + powder coat) and KW will tell you in person - probably not officially - that they don’t need a refurb unless they are visibly leaking and/or don’t rebound when tested off the car. So it’s an investment that should keep paying you back for many years.
 
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Should add that I’ve measured hub-to-arch and you can get with in about 5mm of stock ride height. In particular, the rear spring perches will go considerably higher than the spec (safely, as far as I can see). So into the range you’d get with normal tyre wear, fitment variations etc anyway.
 
I'm a man who enjoys corners and camber's, more than straight line speed. My ///MR was still on it's original shocks until the day it died at 78k miles. The handling was still pretty decent and no leaks or issues. As Tom says The thing to sharpen up the ///MR's handling would have been a faster rack. So, if your not tracking your car, then I would not rush to get the shocks changed, just for the sake of it.
 
Worth mentioning that the shocks fail over time anyway and its not just milage its age. Just because they arent leaking doesnt mean they are working well. The reason so many cars have issues with springs snapping because the dampers just arent working.

Often, the dampers have no resistance but show no signs of fluid leaks.

That was what I meant from my comment, my newer Z4MC handled way better than my now 10-year-older Z4MR. My MR feels wollowy which is not how it should feel.

I disagree about pushing the car hard to find that the car handles poorly. Its not just handling, its the performance on uneven surfaces they are so skitish and its down to how much its dampened and in the rear there is barely any at all. UK a-b roads are generally not smooth and it is more challenging to drive quickly.

Its the difference between having the confidence to push on or pulling back which is essentially why the Z4M was panned at launch. The Box/Cay just doest have that issue and a suspension change goes a long way to improving it. Its not just because you sit so close to the rear axel.

With long-term ownership, I think you just get used and forget what it was like when it was new. Driving cars with OE vs upgraded suspension back to back its incredible what a difference it makes.
 
buzyg said:
I'm a man who enjoys corners and camber's, more than straight line speed. My ///MR was still on it's original shocks until the day it died at 78k miles. The handling was still pretty decent and no leaks or issues. As Tom says The thing to sharpen up the ///MR's handling would have been a faster rack. So, if your not tracking your car, then I would not rush to get the shocks changed, just for the sake of it.
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To be fair this is where my head is right now

However my impatient ‘wanting to do something to improve the car’ means I think I should do the suspension for all the reasons stated

I just don’t want to do that and make it a backward step
 
Put KWv3s on - they are the best bang for buck you can get in terms of longevity, cosmetic sustainability and adjustability. Stick a set of H&R ARBs at strut brace and good trailing arm bushes and you are sorted. As for vibratecs, I wouldn’t stress, new OEM mounts suffice. Remember, you can “over-mod” these cars!
 
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