Anyone riding on KW V1 or ST X coils? Overhaul and general suspension Qs.

[belcom]

I used to have a set of KW V1 on my 11 335xi for my daily, it was perfect for me in terms of ride comfort and it was firm enough to make the car handle perfectly. Got rid of the jarring/crashing of the stock suspension. It was glued to the road.

Now that I have new to me 2006 Z4 3.0si roadster with 90,000kms and after driving it around a bit, I realized how terrible the stock sport suspension is. I feel every single little thing on the road and it wonders left and right really badly. While the steering appears to be very sloppy and way too light (plan on playing with the worm gear ring in the steering column to tune out the lightness). I also seem to be jumping up and down in my seat because of this. Doesn't feel like BMW...

Either way, I am planning to overhaul the suspension so that the car can be actually enjoyed. Its clear that the previous owner was completely oblivious to the fact and told me there's really nothing wrong with it and that it needed much needed TLC.

So I would like to change out springs/shocks, FCABs, possibly new control arms (or new ball joints in the old arms), RTABs, add front reinforcement plates and rear as well. Possibly a strut bar and sways or at least new bushings for the sway bars and new links.

I'd like the car to handle really well for street use and perhaps light track duty but at the same time keep enough comfort for long road trips and such so that I cannot hear my lunch splashing around my stomach

For coils or spring shock combo I thought of ST X (basically KW V1 without stainless shocks) or Bilstein B12 Pro-kit (basically Eibach springs and B6 shocks). KWs were really good on my 335 so I am thinking it would be just as good on the Z. But its a different chassis altogether so it might not be the case.

For the bushings, I am not sure if makes sense to just replace everything with original bmw parts or go for poly or some other type of bushings. Maybe Mayle HD or something?

I'd like to keep everything at reasonable $$ too. Since this is a fun weekend car that I kind of made fit into the family budget I have to be reasonable and fair. The suspension work will be done by myself.

So is anyone riding on ST X or KW V1 and how do you find the ride quality with the Z e85/e86 chassis?

Any suggestions and input on the rest of the overhaul is greatly appreciated as well. Thank you.

[Willy Sea]

Originally Posted by belcom

I used to have a set of KW V1 on my 11 335xi for my daily, it was perfect for me in terms of ride comfort and it was firm enough to make the car handle perfectly. Got rid of the jarring/crashing of the stock suspension. It was glued to the road.

Now that I have new to me 2006 Z4 3.0si roadster with 90,000kms and after driving it around a bit, I realized how terrible the stock sport suspension is. I feel every single little thing on the road and it wonders left and right really badly. While the steering appears to be very sloppy and way too light (plan on playing with the worm gear ring in the steering column to tune out the lightness). I also seem to be jumping up and down in my seat because of this. Doesn't feel like BMW...

Either way, I am planning to overhaul the suspension so that the car can be actually enjoyed. Its clear that the previous owner was completely oblivious to the fact and told me there's really nothing wrong with it and that it needed much needed TLC.

So I would like to change out springs/shocks, FCABs, possibly new control arms (or new ball joints in the old arms), RTABs, add front reinforcement plates and rear as well. Possibly a strut bar and sways or at least new bushings for the sway bars and new links.

I'd like the car to handle really well for street use and perhaps light track duty but at the same time keep enough comfort for long road trips and such so that I cannot hear my lunch splashing around my stomach

For coils or spring shock combo I thought of ST X (basically KW V1 without stainless shocks) or Bilstein B12 Pro-kit (basically Eibach springs and B6 shocks). KWs were really good on my 335 so I am thinking it would be just as good on the Z. But its a different chassis altogether so it might not be the case.

For the bushings, I am not sure if makes sense to just replace everything with original bmw parts or go for poly or some other type of bushings. Maybe Mayle HD or something?

I'd like to keep everything at reasonable $$ too. Since this is a fun weekend car that I kind of made fit into the family budget I have to be reasonable and fair. The suspension work will be done by myself.

So is anyone riding on ST X or KW V1 and how do you find the ride quality with the Z e85/e86 chassis?

Any suggestions and input on the rest of the overhaul is greatly appreciated as well. Thank you.

ST X is a good option, should you want to go down the coilover route.. I would start with replacing your FCAB, and then review your steering and tramlining. Tyre choice and pressures play a big part with this too. You are probably not running runflats now at 90kms, if you are there are considerable benefits in removing them. Recommend staying with standard suspension bushings if replacement required again Meyhle or Lemforder are good.
There is a wealth of experienced commentators on this forum, had only good advice ourselves with a 3.0si coupe.

[belcom]

Unfortunately, tires are run flats. For some strange reason people stick with the run flats and make it sound like its a good thing when selling their cars

Having said that, on my old 335xi I've driven 3 winters with KW V1s and winter run flats which was really harsh and unforgiving with stock suspension. The ride was perfectly compliant with KW and same tires though. And nearly perfect with light weight 19s and Michelin PSS.

I am planning to get rid of run flats. But hoping that replacing bushings and suspension will make a big difference. Also really hope I can get the steering tighter after adjustment. Tires will be changed after that.

Will be doing some shopping soon just need to understand which parts I need and make a list. Planning to start wrenching on it before spring so that I am ready to hit the road fully prepared. Planning some road trips with wifey already. Top down cruising is going to be great. The Z4 seems to be getting a lot more attention from me than my new 540i daily love the 5 though. that thing is a beast!

ST X coils have been ordered. Excited

[winnipegz4m]

Bilstein / Eibach combo bottoms out harshly over certain types of road imperfections - think pothole lips, expansion joints, etc.
Also I found the B/E setup settled too low, esp in the front, which is nearly tucked.

[Steeler]

I have Koni adjustables and ST coils on my non M.
Lowered about 1” both ends
Front struts set at full hard and rears at around 3/4 full hard. No bottoming out or
fender liner rub.

[Vanne]

change the run flats first...

[belcom]

Hello Z crew, thank you for replies and suggestions.

I did inspect the front and rear suspension components last night and found that my front shocks are definitely completely shot and both have leaked out. I think that explains the ride quality at the moment. Also, I did look thoroughly at control arm ball joints, the control arm bushing, sway bar links and didn't find any play or broken rubber. It all looks pretty good. I am sure its not new but definitely not broken and for 90,000km it looks like the front was refreshed at some point.

The rear shocks don't appear to leak, springs are not broken, but some of the bushings might have some small play in them. I have to look at it a little more.

RFTs will definitely go before the season starts and I will most likely change out the wheels for lightweight 19s and Michelin PS4 when time comes.

ST X coilovers have been shipped, I am also going to be ordering front/rear shock tower reinforcement plates and also new front/rear shock mounts to prevent any possible damage. I also want to change the sway bar bushings to something a bit harder. I thought the stock ones are quite soft (I may be wrong but I can feel how soft it is just by pushing from the side). I have a feeling a harder compound bushing will improve steering response and directional stability.

In regards to sway bar links though, would I need new shorter ones? I am not going to be dumping the car to the ground, not my intention at all. I am after probably one finger or a bit less between tire and fender both front and rear. But ultimately want to stay within ST X spec for proper operation and longevity. If that means more than one finger gap then be it. It will all pan out during the install.

[Spec-Al]

Looking forward to hearing more (and seeing pics!)... trying to make the same decision.

[CJW2OO4]

I did the same years ago when I picked up a Z4 Coupe with 62k miles. I ended up doing new OEM ZHP control Arms, CABs, KW V1, New front mounts, and rogue RSMs. That car drove incredibly well for 65k miles before I sold it. Also got rid of the run flats. I'd definitely go for the kw due to the corrosion resistant struts.

[Spec-Al]

Very curious to see if you can run the stock m sport suspension ride height with these. Or maybe even higher? I scraped the front bumper loading the car on my trailer... My Spec e30 has no problem clearing.

[belcom]

Well its warming up here a little. Need to do some garage cleaning before I start taking things apart. But will start working on it soon enough.

CJW2004, glad to hear that it was working well for you. I am looking for that big improvement myself. Although I am not planning to change out the control arms right away, I am going to be changing to powerflex FCABs and also poly front sway bar bushings. New top mounts will go in as well as new rear mounts with reinforcement plates and stuff.

Did you change out the sway bar links at all in your setup? How high/low did you go with KWs?

I understand the stainless part of the KW proposition and I had them before. However I can't justify paying close to $1 CDN more for KWs as opposed to STs with the same exact performance especially given the fact that I will not be driving this car in winter at all. That cash will be spent on a few other things the car needs

[Spec-Al]

CJW2OO4 I noticed in the application notes for the KW V1 for Z4 non M that wheel spacers may be required for stock wheels. Did you run into this problem at all?

belcom Curious if you did you end up installing these?

[1messedupZ4M]

I wish they made the ST-X in "Z4M" fitment.

I have them on my E46 M3 and my R53 Cooper-S and they are easily the best comfort coilover I have ever purchased in my life, on both vehicles they ride better than OEM...

[belcom]

Originally Posted by Spec-Al

CJW2OO4 I noticed in the application notes for the KW V1 for Z4 non M that wheel spacers may be required for stock wheels. Did you run into this problem at all?

belcom Curious if you did you end up installing these?

I am getting close, decided to service the engine first. Have it apart now and waiting for parts. But suspension will be done immediately after.

So far, I've heard only great things from other guys including 1messedupZ4M here. Personally I've not had many coilovers but it seems I've hit the target with kw v1 when I bought them for my e90 few years ago. I think its hands down best street option available for a price that will not burn holes in your wallet. I can't wait to get the ST Xs on my Z4 but first things first.

Here are a couple pics to make things a little more interesting The pic of the car is at a dealer when I did the PCV blow by heater recall on the N52 recently. I thought the lighting was good and snapped a couple shots.
Suspension is not yet installed at this point in time.

[belcom]

Installed. Breaking in for now. I think I am going to raise it 1.5 -2cm