Shocks going bad? Suspension upgrades

s512

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British Zeds
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Z3 3.0
Hi all,

My Z3 3.0 is feeling a bit 'slack' - the way it's always been (in my ownership) and think it's time to tighten things up a bit. It seems to nose dive quite a bit when braking at low speeds... and raise at the front on acceleration... more than you would expect for a sports car. I haven't got anything to compare it to, but I'm thinking the shocks are going bad...

It's at 106,000 miles and I haven't got any receipts for replacement shocks... is there a way of testing shock performance? Is it outrageous to assume these shocks might be the originals? I heard they have a life of around 70k, but I guess this is performance related... and could go on longer if they don't leak...

I'm thinking of replacing with Bilstein or Koni shocks, plus maybe slightly lower springs later down the line, such as these: http://www.demon-tweeks.co.uk/performance/lowering-springs/eibach-sportline-lowering-spring-kit - just hope speed bumps don't become a big issue! Can anyone share their experiences with lowered springs?

Many thanks!
Sam
 

GazHyde

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Is it outrageous to assume these shocks might be the originals?
It's possible. I found these labels on my rear when changed on 105k miles (2001 model). We believe that these may be the factory stock stickers (although don't have any confirmation we haven't seen labels like this before on the other Z3's we've worked on).

Both of mine would easily compress fully, one would stick in and the other came out at a snails pace. As far as we could tell they were empty and not really providing much in the way of damping that's for sure!
2014-11-29 15.58.45.jpg
 

Daz999

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Just to add to Gaz's post, here are pics from my 2001 (built) 2.2 sport with 72500 miles.


As you can see, not a lot of rebound since i compressed them on Saturday.......


Sticker pic for info

I've gone with Sachs replacements from ECP, cant give an update on handling or comfort yet as the car is sorned. I'm toying with the idea of standard springs rather than the slightly lowered M sport spec ones.
 

s512

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British Zeds
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Z3 3.0
I stuck a camera under the car just now to try and get a shot of the label... appears to be the same, so could well be originals. Different part number, but that could be your sport vs my standard.

2015-03-10 18.00.28.jpg

I think new shocks are the way to go though. Daz, when you say M sport spec springs, would these be from a Z3M or Z3 sport model (from 2001+ I believe)?
 
Z

zedonist

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The Bilstein B12 kit is the way to go, you get B8 performance dampers and Eibach springs, fantastic sporty and lush ride.
 

Daz999

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Yes its a m sport rather than the hardcore Z3m. The m sports were 1.9, 2.2 and 3.0 models with a suspension that was 15 or 20 mm lower than standard and possibly uprated ARBs. So the eibach kit is lower again than m sport with a 30 mm drop from standard.
 

s512

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Yes its a m sport rather than the hardcore Z3m. The m sports were 1.9, 2.2 and 3.0 models with a suspension that was 15 or 20 mm lower than standard and possibly uprated ARBs. So the eibach kit is lower again than m sport with a 30 mm drop from standard.
Interesting. That's another option... do you have a part number for these springs, or know a rough price? I can't find them on the net.

The Bilstein B12 kit is the way to go, you get B8 performance dampers and Eibach springs, fantastic sporty and lush ride.
That's the front runner at the moment. The B6s allow for a drop of 30mm, but over time the drop will increase and I don't want problems in the future... so B8s look like the way to go. Can I ask how much you paid? Demon tweeks prices seem to be all over the place.. I'm sure I saw the B8s for around £70 the other day - now they're up to £112. Or I'm seeing things.

Only problem is that I was hoping to do shocks for now and springs at a later date. However I don't think this is advisable with B8s...
 
Z

zedonist

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The B6 and the B8 are the same performance, but the B8 is shorter to work better with lowered cars, I would not buy them as separates, it is cheaper to by the B12 kit, dampers and springs cost £500 delivered from Germany two years ago.
 

Dino D

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This is why I've gone for coilovers again but this time with adjustable dampers as well as height. If I'm going to spend the cash I want to have full adjustability as things change (ie you move to a housing estate with speed bumps, you decide to make it a weekend/track day toy and want more firmness etc etc..)

The BC racing kit I've got makes damper adjusting a doddle.

Have a look on this thread for full details: https://zroadster.org/index.php?threads/Project-Dino-D.6735/

Picking it up this weekend but @Lee has already tested it and thinks it rides well, will report back soon!
 

Dickymint

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I read some place that coilovers go out of spec over time and need to be recalibrated also if they are not used often or hard enough they can get sticky or even seize up, now I don't believe everything I read on the net but It did stop me buying some for my old car :)
 

Dino D

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I read some place that coilovers go out of spec over time and need to be recalibrated also if they are not used often or hard enough they can get sticky or even seize up, now I don't believe everything I read on the net but It did stop me buying some for my old car :)
I would say any car needs alignment and suspension check ups over time regardless of what suspension is on it..regular springs and shocks sag over time too. You see plenty of standard Z's sporting drift-car camber as the rear sags and throws everything out (the rear camber changes on these as it sits lower).

BMW (and plenty other makers I should add) now supply springs that have a habit of snapping too (more prevalent on the newer ones though).

As for seizing up I had some seemingly low quality top mounts and the bearings did seize. This time I've bought proper ones (the BC Racing comes with proper ones included). But that is the mount.
Perhaps you mean the adjustment threads seize up- that will happen on lower quality items not made from Stainless. I've got stainless on the BC's.

In my experience this far I think you definitely get what you pay for but you don't have to pay over the odds for good stuff (just like with any suspension really).
 
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s512

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Z3 3.0
Thanks all.

This is why I've gone for coilovers again but this time with adjustable dampers as well as height. If I'm going to spend the cash I want to have full adjustability as things change (ie you move to a housing estate with speed bumps, you decide to make it a weekend/track day toy and want more firmness etc etc..)

The BC racing kit I've got makes damper adjusting a doddle.

Have a look on this thread for full details: https://zroadster.org/index.php?threads/Project-Dino-D.6735/

Picking it up this weekend but @Lee has already tested it and thinks it rides well, will report back soon!
I'd be very interested to hear feedback on these. Your zed looks like it's getting a good overhaul...a nice read! Hadn't considered coilovers as figured the cost of quality items was far greater than a set of new quality shocks and springs. It only seems to be a little more, and you get the full adaptability. I wonder if they'd be firmer than the bilsteins on their softest setting?

Sam, sorry i can't help with the part number. I've checked on realoem.com using my VIN and rather unhelpfully it directs me to a BMW dealer as it depends on what options were fitted to my car :rolleyes:

http://www.realoem.com/bmw/showparts.do?model=CN12&mospid=48081&btnr=33_0856&hg=33&fg=45
Appreciate you checking. I had a look before, but the system doesn't seem to differentiate between sport and non sport, at least when viewing suspension.
 
Z

zedonist

Guest
I dont think the springs on the sport are different, I think they use the thinner spring pads, which gives about 15mm reduction in height at the outer wheel surface.
 
Z

zedonist

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In not know to be honest, I do know that you can buy the rough road package which gives you bigger springs, and in all the literature I have seen there is either white label or red label springs so I assume one is the rough road option, but you know what assume did. But by knowing the length of an OEM spring we can work out the trig to see the difference at the wheel with thinner spring pads.
 
Z

zedonist

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Just checking springs for my 1.9 and a fellow members 2.2 sport on euro car parts gives the same part number for the rear spring, so does substantiate it a little I think.
 

tower

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Sorry just saw this...am replacing rear suspension on my2001 bmw z3 2.2i sport. Rear sport springs bmw no. 33539070477
 

AussieZ3

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The first owner of my Z3 1.9l had fitted 'Eibach' Pro Kit springs when the car was only 3 years old. The car is lowered 25mm but he kept the genuine shocks. Due to reduced clearance the drip tray under the engine has suffered damage and the wheel touches the arch when driving over uneven surfaces at high speed. I am considering changing back to BMW genuine springs but concerned if the handling would be affected.
 
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