New rear suspension

R

RayM

Member
 Cheltenham
Hi All

Any recommendations for changing / upgrading the rear suspension on my 2003 E85? I've looked all through the documentation I got with my car and can't find anything showing any work on the rear suspension. It's only done 72k so could it still be on the originals I wonder? It drives fine but I've read so much on how things can be improved by upgrading, although I'm not interested in lowering or anything just improving the standard set up.

Cheers
 
Any ideas on this guys? Non OEM parts as I understand that the original fit parts are not good quality, advice please
 
I just went through this. If you want to maintain the ride quality the same, then original or OEM is best. Anything else is likely to stiffen up the ride and make it less plush.

At 72k, if the absorbers have never been changed before, they are most likely toast and overdue for replacing (Sachs and Boge make the M sport absorber and they don't come cheap but at least are matched to the M sport spring. You can also opt for the regular Sachs and Boge on the non M sport suspension although it will not be optimal). Also good to check if the bump stops are still intact, condition of the top hat/mounts and if the M sport springs are broken.
 
I haven't done this myself yet but most who change to Eibach springs report that it actually improves the ride quality particularly around town/slow speeds etc. This seems to be due to the fact that the eibachs are a progressive spring and the standard ones are not. Plenty on this subject all over the forum. The amount the eibachs lower on a 3.0 like yours is minimal as you already have m sport suspension which is 10-15mm lower than standard anyway, the eibachs add another 15mm approx to this so its not like your slamming the car on its arse.
You would hope the eibachs couple to some fresh m sport or even non m sport dampers would deliiver a much more compliant ride.
To be honest I not sure which of the OEM dampers work best with eibachs as the springs are listed for both types of suspension
 
I am also interested in this thread as I am due for a suspension refresh. I can't decide if I want eibachs or just use the OEM springs, as I am also on the M sport suspension. I'd ideally like the car to be more plush, and it seems like for smaller bumps the eibachs do just that. But at the same time I really don't want the bad bumps in the road to be worse, as I live in new york and our roads suck here. Any more opinions as to whether I should do eibach springs with new dampers or just swap out the dampers and use the original springs?
 
OE springs snap and are expensive, so why bother? I've never heard of Eibach springs snapping and can be had for about £120 all round. If you're changing the springs you might as well change your shocks, and if you're doing the rear you might as well do the fronts too. My rear shocks were junk at about 80k.
OE shocks are also expensive, Bilstein B4s are equivalent to OE and can be used with lowering springs but B8s are upgraded and properly matched.
You could also consider coilovers depending on your budget, what you want to achieve and how long you plan to keep the car.
 
Scooba_Steve said:
OE springs snap and are expensive, so why bother? I've never heard of Eibach springs snapping and can be had for about £120 all round. If you're changing the springs you might as well change your shocks, and if you're doing the rear you might as well do the fronts too. My rear shocks were junk at about 80k.
OE shocks are also expensive, Bilstein B4s are equivalent to OE and can be used with lowering springs but B8s are upgraded and properly matched.
You could also consider coilovers depending on your budget, what you want to achieve and how long you plan to keep the car.
Click to expand...

Sound advice right there. :thumbsup:
 
Don't have experience with the Eibach springs + B8 absorbers (B12 kit) but from what I have been told by independent BMW garages in two different states, this setup is way harsher than OE and with that 30mm drop (compared to 10mm for the M sport over stock), there is definitely reduced suspension travel and ground clearance.

Yes the M sport rear springs (they are progressive as well) are known to snap but there is the Suplex rear spring replacement and absorbers are a wear/tear item regardless if you spring for OE or Bilstein or Koni etc.
 
Hi guys

Thanks for all the input, more confused than ever know :(

I've checked my vehicle spec and it indeed has the 704 M sport suspension. I don't want to make it any harsher
So if I want to maintain the current ride height etc I have to use the OEM products (Sachs & Boge) is that correct?

I'm working on the premise that prevention is better than cure so I will probably do the springs with the dampers and most likely front and rear. What's a ball park cost?

Cheers
 
Sorry, one other thing, are the springs just as likely to fail on the M sport suspension as on the standard set up?
 
The rears just all seem to snap. I jest that they have a half life...

Budget about £125 for OE and Myele HD mounts and accessories front and rear.

No idea how much you can get the other springs for but if you go for a set of B6s they're about £3-400.

Are you doing the work yourself? That will save a fair cost. If you want to keep the ride height then it might be worth looking at coilovers. Someone mentioned a set that can be had for about £700, have a search - I cant remember the name.
 
Suplex rear M sport spring replacement cost:
https://www.ecstuning.com/BMW-Z4-3.0i-M54_3.0L/Suspension/Springs/ES2915132/

Shock absorber pricing (from a US vendor; but there are many option/choices out there if you Google like DC Performance, Demon Tweaks etc.):
https://www.ecstuning.com/BMW-Z4-3.0i-M54_3.0L/Suspension/Shocks/

Some feedback on the Eibach+Bilstein B8 AKA B12 kit:
http://www.z4-forum.com/forum/viewtopic.php?t=73188


The M sport spring spring rates in lbs are:
Front (1-4 inches of travel)
160-220

Rear (1-4 inches of travel)
240-420
 
I am very happy with my B12 set, it doesn't feel firmer than stock m sport, even if it may well be on paper.
I find it less crashy over bumps if that males sense, you still feel them but they are less sharp.
Some of that may well be due to the original shocks being toast but for about £600 the set it was a pretty reasonable option. I don't find the drop a problem except on the highest of speed bumps and the handling is much better.
 
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