Suspension B16 upgrade

Ouroux71 · Post by **Ouroux71** » Wed Sep 16, 2020 10:54 am

Recently changed the shocks and springs on my 23sdrive.. It has done 45K miles..

Purchased in April this year I was very disappointed with the handling/noise/damping ... I quickly changed the 8 year old run flat tyres on 19 inch alloys (they had loads of tread but were obviously out of date)... The Goodyear tyres made a good improvement on road noise and imperfect roads. but did nothing much on the handling front.. I found the car quite un-nerving on faster corners..

So a car that looks the part but failed to please.. After taking advice I had the suspension uprated with Bilstein B16 adjustable shocks and coils - an expensive change.. At present they are set to 3 (maximum firmness is 10).. This kit lowers the car by 3cm.. The old springs and shocks looked in decent shape (nothing broken nor any shock leaks)

First impressions after the install were that it was much, much better.. More predictable and it rides more flat...

1000 miles later I have to say I'm still dissatisfied overall and I'm thinking it must be down to the inherent E89 handling/weight issues..

I love the roof and looks of the car but wondering if I should have saved up more for a Porsche Cayman (don't like the Boxster looks even if it is much the same vehicle).....

Zikim · Post by **Zikim** » Wed Sep 16, 2020 11:02 am

If you add uprated anti-roll bars front and rear from H&R it significantly improves the handling. I fitted BC Coilovers to my 35i but the handling still wasn't right but 3 months ago fitted the H&R ARB's and my zed's body doesn't roll anymore - quite a transformation

Pbondar · Post by **Pbondar** » Wed Sep 16, 2020 11:59 am

Could you articulate what about the handling you don't like please?

Ability to turn into a corner

Ability to hold a line in a corner

Ability to cope with bumps

Weight of steering

Lack of feedback on steering

Feeling of insecurity

etc etc

Ouroux71 · Post by **Ouroux71** » Wed Sep 16, 2020 1:24 pm

Yes I was not great in my description. I put a reply to your thoughts - thanks for this idea.

Pbondar wrote: ↑Wed Sep 16, 2020 11:59 am Could you articulate what about the handling you don't like please?

Ability to turn into a corner: has plenty grip but seems to need lots of guidance rather than the car finding the flow of the corner - figity....

Ability to hold a line in a corner: once in the corner it holds and builds up the corner loading but it feels again a bit unsettled..

Ability to cope with bumps: it doesn't get too upset by just bumps.. Roads with a big camber and non level roads are worrying as thr vehicle requires a lot of feedback..

Weight of steering: wow.. I think no-one likes Toyota Camry type light steering but I do find the Z4 is a real work out.. Okay I'm not fragile and not old but this weight is a hindrance rather than giving worthwhile feedback.. Yes the steering weight is not my favourite thing.

Lack of feedback on steering: I feel I get plenty of feedback so much that the vehicle never settles down and I'm working on it all the time (except of decent flat A roads, motorways etc.

Feeling of insecurity: yes this is an issue too.. Loading the Z4 up on a big roundabout and letting it work hard it can do the job.. But the steering needs a lot of weight.. At higher speeds I am less keen to try this as I feel the balance/weight is going to push the Z4 off the line and everything would get bad quickly.. Like the front half of the vehicle would take control and do what it wants to do rather than me..

Does that make sense?

etc etc

Ouroux71 · Post by **Ouroux71** » Wed Sep 16, 2020 1:36 pm

Zikim wrote: ↑Wed Sep 16, 2020 11:02 am If you add uprated anti-roll bars front and rear from H&R it significantly improves the handling. I fitted BC Coilovers to my 35i but the handling still wasn't right but 3 months ago fitted the H&R ARB's and my zed's body doesn't roll anymore - quite a transformation

Thanks....
Like these? https://brandzperformance.co.uk/index.p ... ct_id=4408

A costly fit?

Zikim · Post by **Zikim** » Wed Sep 16, 2020 2:01 pm

Ouroux71 wrote: ↑Wed Sep 16, 2020 1:36 pm
Zikim wrote: ↑Wed Sep 16, 2020 11:02 am If you add uprated anti-roll bars front and rear from H&R it significantly improves the handling. I fitted BC Coilovers to my 35i but the handling still wasn't right but 3 months ago fitted the H&R ARB's and my zed's body doesn't roll anymore - quite a transformation
Thanks....
Like these? https://brandzperformance.co.uk/index.p ... ct_id=4408

A costly fit?

They're the ones, can be a diy fit at home taking 2-3 hours.

Pbondar · Post by **Pbondar** » Wed Sep 16, 2020 3:56 pm

Thanks, and for reference what cars do you drive that provide your reference points for your judgements..sorry its 20 questions ..

Ouroux71 · Post by **Ouroux71** » Wed Sep 16, 2020 4:48 pm

20 questions is not a problem...
My main car is an Audi A4 Allroad..

Pbondar · Post by **Pbondar** » Wed Sep 16, 2020 6:01 pm

Well as a former Audi 80/A5/A5/A7 Quattro person I know what you mean..

My suggestions in order of costs / ease are..

A full 4 wheel align check..some of your observations appear like too much camber..my E89 took 2 attempts..I had to change some bushes to get it all to line up..

Tyre pressures...I would experiment from a low of 32/34 psi (pls convert) to 38/40 with a max of 4 psi differential front n rear

After that..

The ARB won’t improve, IMHO, your driving sensations and with 19” alloys / tyres I think will feel harsh..

With 17/18 wheels ARB will help the bends a bit At the risk of bump steer if set up too harsh..

The bump / compression damping should be set to about 20% more than stock BMW figures..

I suspect the spring rates are a bit high can you back them off?

On my car I found that 17 wheels gave the best handling by far, 18 gave a harsher ride with no benefit...maybe a little worse ..I binned the 19 after the first drive..albeit with runflats ..

I did the mod using E90 M3 steering parts which gave the final touch..

Mine now handles very very well..like an Audi but less weight over the front..

Jakg · Post by **Jakg** » Wed Sep 16, 2020 7:51 pm

I've not seen anyone do it on an E89, but on the E90/E88 a common mod is to swap the standard front wishbones for the M3 items. I've just finished this on my E91. It's the same part on an E89.

Having said that - I've done the above alongside a B12 kit on my E91 (obviously I appreciate this is a pretty terrible comparison) and a lot of the negative characteristics I didn't like are significantly reduced - but it's still bigger and heavier than my E85, and you feel the mass moving around more.

Ouroux71 · Post by **Ouroux71** » Wed Sep 16, 2020 8:05 pm

Pbondar wrote: ↑Wed Sep 16, 2020 6:01 pm Well as a former Audi 80/A5/A5/A7 Quattro person I know what you mean..

My suggestions in order of costs / ease are..

A full 4 wheel align check..some of your observations appear like too much camber..my E89 took 2 attempts..I had to change some bushes to get it all to line up..

Tyre pressures...I would experiment from a low of 32/34 psi (pls convert) to 38/40 with a max of 4 psi differential front n rear

After that..

The ARB won’t improve, IMHO, your driving sensations and with 19” alloys / tyres I think will feel harsh..

With 17/18 wheels ARB will help the bends a bit At the risk of bump steer if set up too harsh..

The bump / compression damping should be set to about 20% more than stock BMW figures..

I suspect the spring rates are a bit high can you back them off?

On my car I found that 17 wheels gave the best handling by far, 18 gave a harsher ride with no benefit...maybe a little worse ..I binned the 19 after the first drive..albeit with runflats ..

I did the mod using E90 M3 steering parts which gave the final touch..

Mine now handles very very well..like an Audi but less weight over the front..

I had a 4 wheel alignment done... I asked about those M3 E90 parts and was told it wasn't required.. I have been thinking about the tyre pressure so I'll maybe have a try with that.. More pressure on the front I would guess?
19 inch wheels... Yes not the best idea but they came with the car and they do look good..

I don't want to keep adding more cash if it won't work.. The recent work done was already a lot.. I will play with pressures and think about those other things... Upgraded ARB's and E90 M3 parts.. Both of them would another £1000 on top of my recent works..

Pbondar · Post by **Pbondar** » Wed Sep 16, 2020 8:44 pm

What tyres and pressures are you running

Ouroux71 · Post by **Ouroux71** » Thu Sep 17, 2020 8:23 am

Running Goodyear Eagle F1 front and rear.... Pressure 38psi all round..

No idea how to back off the springs as I had the work done .. It does have a set of B16 matched adjustable shocks and coils which I was told were set at 3/10max stiffness front and rear.. It also had a full 4 wheel alignment. I had the car worked on at AR Performance, Kings Lynn.. They are a mini and BMW independent specialist who seem to have a good reputation..

enuff_zed · Post by **enuff_zed** » Thu Sep 17, 2020 8:33 am

Ouroux71 wrote: ↑Thu Sep 17, 2020 8:23 am Goodyear Eagle F1 front and rear.... Pressure 38psi all round..

I would have expected the fronts to be lower than the rears tbh.
Follow Pbondar's suggestion: drop the front to 36 to begin with, then try moving them around a bit until you find what you like, but keep the front to rear difference.
FWIW, though I am on 18s, I ended up 34F, 36R on Goodyear Assy 5s.

Ouroux71 · Post by **Ouroux71** » Thu Sep 17, 2020 8:58 am

Thanks for that tip... I'm off on a project for a few weeks so I won't be able to do any testing now but I'll do some tests when I'm next back home.. I'll start with 34 F and 36 R as that should give me the best chance to feel what changes if anything...

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