Z4 Suspension/bushes options, ideas and advice (B12 Kit)

H

hopz121

Veteran
 Guildford Surrey
I am thinking of re-freshing some of the suspension on my car, and I am after some advice especially on shocks/springs etc

So far i have booked in for poly bushing of the lollipops (they are shot and have a fair amount of play)

I have done poly bushed the front ARB bushes already and added new Meyle HD drop links, the wishbones and track rods have all been checked and are showing no play so ill leave them for now.

The rear suspension top mounts are currently ok but hasn’t got long left it them they have started to wear out so it will need doing soon (next couple of months) , the rear trailing arm bushes are ok currently but I plan on replacing they with poly bushes around in the summer.

I am debating on whether to change the shocks all around, the car has done 100k miles now so I’m guessing they are past their best but do I just replace the shocks or do I get a bilstein B12 kit? Or B4 kit?

Any advice?

Has anyone struggled with day to day driving with a lowered zed? (the car is a daily driver so can’t be silly low)

Would just changing the shocks be a noticeable improvement?

Would a shocks and springs kit be worth the extra cash and will I notice a big difference?

Thanks

Ash

P.s Sorry for the long winded post :)
 
Seems the route you're going down may increase NVH (noise, vibration, and harshness)

Yes, you'll see a nice improvement but as for daily duties, it may become a little irritating. My car isn't silly low, bit it's enough to catch on some speed bumps and such (and almost get beached on a bump in Waterloo :lol: )

Fortunately it's my weekend toy so I can live with the shortcomings of lowering my car.

Hopefully someone will be able to add to that.
 
Bilstein dampers:

B4 - OEM replacement
B6 - uprated dampers suited to standard ride height
B8 - Uprated dampers suited to lowered rode height approx. 30mm
B12 - this is a kit comprising of bilstein B8 dampers and Eibach Pro Lowering springs.

You will likely notice ride may be a bit harsher but just changing the dampers won't lower the car. The polybushes will contribute far more to NVH than the Bilsteins imo!
 
For info, and this is purely my experience, pitting poly bushes has had no noticeable effect on road noise or road comfort. The Z is hardly a comfortable cruiser, especially in M-Sport guise like most of the 3.0i models will be. On other cars on softer suspension and with an element of comfort, yes you would notice it, but not on the Z.

To answer your question, yes you'd be best replacing everything. Shocks should last about 100k but they may have longer left, but in any case replacing them will make a difference. You can't go down the B4 route unless you are on standard SE suspension as they are not for lowered cars, so B8 are the best option for the sporty set up, but there are other options out there for less money (not sure if that equates to less quality).

Top mounts (front and rear) are a no brainer if your changing the shocks as you have to take them off anyway. Front top mounts are a common failure item as the bearings seize up and the whole mount loses rigidity, but few people ever seem to check these.
 
I have read B4's can be fitted to standard m sport suspension so is this not the case then?

The people in the know seem to think that the front poly bushes won’t ruin the ride/comfort at all but the rear trailing arm bushes will cause a bit more road noise/ vibrations but they are a worthwhile upgrade and stiffen up the rear of the car a lot.

Does anyone recommend any good standard shocks?

Is anyone running a B12 kit then? Do you get problems with speed bumps and car parks? Anyone using a lowered car as a daily?
 
B4's can only be used with standard suspension and not lowered.

B6's can be used with suspension that is lowered to a maximum of 30mm and therefore can be used with the sport suspension which is lowered by 15mm.

B8 dampers can be used with suspension lowered to 40mm.
 
I will over the course of th next few months be fitting a b12 kit, with new top mounts front and rear, new droplinks front and rear, and polybushed rtabs, and front wishbone lollipop bushes.

My feedback may be irrelevant by the time I've fitted this lot and can report back, but I'll pop it up anyway as and when I can!
 
Just ordered and received, 2 new wishbones (control arms) with rear bushes already installed and nice new ball joints, 2 drop links, 2 front strut top plates, 2 rear strut top plates and 2 trailing arm bushes. After much forum post reading and deliberation, I agonised over powerflex poly bushes but in the end went for Meyle HD for the whole lot, at £295. All I've got to do now is wait for the rain to stop and I can fit it all. Why Meyle? I reasoned that, even if poly only introduced 10% more stiffness (harshness) to the ride, it would be 10% more than I would want. Also spoke to one or two specialists who agreed the poly bushes do produce a harder ride, guess it figures really, nothings for nothing! more gain more pain. I also reasoned that if the Meyle HD is an improvement in terms of quality on the originals, as is oft quoted, and my car has covered 70,000 on the stock bushes, I shouldn't have to worry for a long time (posts on early meyle failure duly noted).
 
Ed Doe said:
I will over the course of th next few months be fitting a b12 kit, with new top mounts front and rear, new droplinks front and rear, and polybushed rtabs, and front wishbone lollipop bushes.

My feedback may be irrelevant by the time I've fitted this lot and can report back, but I'll pop it up anyway as and when I can!
Click to expand...

If you could keep me updated that would be great, do you use your car as a daily ed?

Are you worried about it being lower?

Cheers

Ash
 
Ash I'd be happy to keep you updated, I'll probably just bung a thread up when I've got the parts fitted, and will keep on the feedback as I put some miles on the car, but as I say I won't be doing it until May so decent feedback is unlikely to follow until June...

Mine is a daily but I'm not fussed with it being lower; I've had low cars before and am happy to avoid speebumps etc! I also really think the zed would benefit from better damping so I'm just going to go for it!
 
I think i will order a B12 in a few months and go from there, it seems like a popular kit and has good reviews from the people who fit them.

I will try and fit the rears myself (hopefully it isn't too difficult) and then get a garage to do the front i think.

I will get new top mounts at the same time, is anything else needed? New bump stops/dust covers?

Ash
 
If you go to the following link: http://www.realoem.com/bmw/select.do

Chuck your vin number in, it should be on a sticker on one of the front suspension turrets inside the engine bay.
Basically if you navigate the list you can see an exploded view of the front suspension components. Personally I think the only thing worth replacing is the bush itself, as the rest should be fine. But if you wanted to replace the lot, you could actually build the suspension units up complete off the car, and then swapping them over yourself would be an absolute doddle; 3 bolts at the top holding the top mount to the suspension turret, and then the pinch bolt holding the bottom of the strut to the hub!
 
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