Z4 Roadster 3.0i Suspension upgrade

S

streetcar

Member
Hi All

I have a 2003 auto roadster 3.0i and am looking to up grade the suspension as I'm not happy with the handling of the car, it moves and skips around in a rather unnerving manner.

I am still running 108 wheels with run fiats at the moment but intend to change both at some point but want to sort the handling / suspension first.

I have a budget of a £1000 excluding labour costs for fitting and have been researching poly bushes, coil overs etc

A huge question as I suppose everyone has a view, but from those who have actually spent money (as opposed to those like me who haven't ) what recommendations can you make in regard to suppliers i.e. Bilstein vis a vis AP poly bush kits / supplier etc.

Also, drop link kits are a part of the equation as is anything which effects the drive character of the car.

The car is only used as a week end and sunny days ride but I don't hang around if you get my drift!

Thanks in advance and regards sd
 
Ditching the run flats will make a big difference.

I have a B12 kit and am happy with it. I do some track work but didn't want to faff with settings.

So: £6/700 for the kit. New mounting bits including bolts about £100 from Soper. If nothing else has been done to your suspension from new then renew the perishables. Poly ARBs front and rear, poly RTAB, new drop links f&r, new wishbones and bushings (poly if you want).

All that without fitting should see your money disappear ;)

For simple road use you could get away with non rft tyres, new shocks and perishables for a bit less.
 
Definitely ditch the runflats first. They are hopeless.

When you say "moves and skips around", can you describe exactly what happens? I have a Z4M with adjustable dampers now and used to have a 2.5si on stock suspension. The ///M is miles ahead on general roll, pitch and handling of uneven surfaces, but it still shuffles about a bit at the back (laterally). You can put bush limiters on the RTABs to reduce this, but I think it's a trait of this car that the rear is a bit skittish. Probably due to suspension geometry, but also because you're sat on the rear axle so all the little movements are exaggerated.
 
As above. The runflats will be causing the skittish feeling, most likely.

Get some decent non runflat rubber on there first. I've just gone from Hankook S1 Evo 2's to Vredestein Vorti's and the difference is amazing.

I had the same skittish, lateral movement at the back with the Hankooks, but it feels fine with the Vorti's.

Also get your rear trailing arm bushes (RTABS) and front wishbone rear bushes (lollipops) changed. I went for Superpro polybushes. I also replaced my anti roll bar bushes (Superpro on one and powerflex purple on the other, can't remember which one has which).

A good 4 wheel alignment will definitely be needed, so budget for that.

Then it's just suspension, top mounts and perhaps an upper front strut brace. Mine appears to make a big difference. It feels less boat like when fitted
 
Thanks for all that guys, on reflection I will start with a tyre change first and poly bushes all round.
In regard to fitting a B12 kit, are these not aimed more for track use as their listed at £800 whereas the Bilstein kits on flebay are £450 and the AP kits are £550 do these not represent better value for a streetcar (pun intended) :D
 
The B12 is simply Eibach springs and B8 shocks. B4 are OE equivalent (though arguably better), B6 uprated twin tubes, and B8 the same but shortened to match the lowering springs. I assume the kit you reference is Eibach's with B4s.

There is the potential for accelerated shock wear on lower springs with standard height shocks - I don't believe it's a massive issue though but the difference in cost isn't huge. Do a job right and do it right was the attitude I took.

It's an old enough car to warrant a suspension refresh, so I think you'd be onto a good start. Exclude tyre costs from your budget though, they're a consumable ;)
 
First get rid of the runflats and then evaluate what it is you want exactly.

I have pretty much all the upgrades you can think of on the suspension, but the runflats give such a huge impact on steering and tramlining that without solving those 2 cons that come with runflats on the e85, its hard to predict what you think should be improved on the suspension.

As for the cost its a bit strange that you dont count labourcost. fully polybushing your car (so all 23 suspension points) is not so expensive to buy the bushings, but to get them installed is quite a job. Whereas coilovers are fairly easy to install but can cost a lot.
Or are you going to install everything yourself. In that case a full bushing/polybush refresh is the way to go, as the stock rubber ages like crazy (polyurethane doesnt age)
 
our E86 used to suffer the same skipping sideways at speed, particularly on concrete motorways. despite being on no runflats.

Have just had wheel alignment and same roads tested that caused uncertainty isnow rock solid.

With so much adjustment these are very sensitive cars to even the smallest alignment issue.
 
Would this set be a good start ??? ( I have same type of issues as OP)
http://www.ebay.co.uk/itm/111518111275?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 
9designs said:
Would this set be a good start ??? ( I have same type of issues as OP)
http://www.ebay.co.uk/itm/111518111275?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Click to expand...

I can't see any brand name mentioned for those.

Personally, I would only go for a well known brand nowadays. I fitted some cheap no brand name droplinks which were finished after 6 months. I then bought meyle ones and they've been fine for 2 years now.

Buy cheap, buy twice.
 
The drop link kit on eBay as mentioned by 9designs, have sold out so they can't be that bad.
GuidoK states 23 suspension points does that include what would be covered in a drop link kit ?
As the run flats seem to be the root cause or at least a major factor in the handling issues they will go first but the split rims look a bit dated and at £120 per wheel for a refresh and then new none run flat tyres, I thought I would go the 19" up grade route. I had considered buying a set of M3 E46 19" but these are over £100 each plus refurb so it's cheaper to buy new.
 
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