Rear suspension questions

C

Conquistador

Member
Okay, I've finally had it with my rear suspension creaking and knocking like an old train. I have to travel up and back down the following long rutted track through a forest twice a day for work:

2ldktc7.jpg


14udtf4.jpg


rk7wpf.jpg


Anyway, it wasn't a problem in my previous car which had air suspension - could sail straight down it. But in the Z4 I find myself either dropping my speed to a snail's pace to gently roll over the bumps and holes and drive round them, or steadily cruising along in 2nd gear which is a little smoother but still gives the poor suspension a hammering.

I'm sure the rear springs have broken (I will be checking them this weekend), and I think it may be wise to replace the rear suspension bushes too, but is there anything else in the rear suspension which causes a problem like this or should concern? Shocks or any mountings?
 
Which bushes are you going to replace. Personally i would go poly bushed on the complete rear axle :thumbsup:

Should tighten the rear end up nicely.
 
I wouldn't go Polly bushes on the diff carrier you will probably get a horrible feeling through the car on gear changes. And if you finding it a bit rough now Polly bushes wont help. Go normal RTAB but with a limiting kit. It sounds like your springs are maybe broke. But a sports car with a springs will always handle very different to car with air?! You cant really compare the two??
 
Have poly black throughout my e36, doesn't make a huge difference. Plus they have lifetime guarantee, where you will probably be replacing OEM in 2-3 years time.
 
I'm with monkey on the bushes front. Poly, by virtue of their material, WILL be firmer.

I've heard many people (usually young'uns) over the years saying their suspension is like OEM after poly bushing, then having tried it for myself, found their words to be inaccurate.

Your dampers could also be shot - for the small additional cost, I'd replace them too.

I will be refurbishing all my suspension and back end at some point - at 87k, everything is worn beyond optimum performance.
 
I wouldn't touch poly on the Z4 again having had it and removed it, especially as you're seeking comfort on a rough track amongst other things.
The Z4 suspension is so flat and harsh that unlike poly on saloons that you don't feel it, on the zed you really do.

As an aside you won't feel it if the springs are broken.99% of folks never know and find out at MOT time as it's only the end 1 or2" of a coil that breaks off.
 
Not sure what bushes yet but I am certain they need changing. The firm ride on the road doesn't really bother me, I'm a 'youngun' :wink:

Just when I do this little bit of off-roading I feel like I'm slowly destroying the rear suspension.

Looking at the Powerflex website, could you offer some preliminary guidance on which of the following I would require if I did go poly?

14icwmt.jpg
 
Thanks for asking this question as I intend to renew as much of my front and rear suspension as I can. Car has covered just over 82k so as has been said, probably needs doing. I will read with interest as I'll be ordering the same parts. Great site and very knowledgable and helpful members. Thanks guys and gals.
 
Rear trailing arm is the main one, but i don't see rear subframe front or rear bushes on that list either.

I think powerflex on anti-roll bar and top moounts is overkill and here would just go with OEM. Though it certainly wouldn't hurt to do both of these if your budget allows.
 
I have just replaced all the bushes on the rear of my car. Its a PITA job well i found it to be. I had the use of a fly press but u guess buying the proper press tools would help. I replaced all the bushes in the upper control arms. Made new adjustable lower arms with new bushes new RTABs with my own limiting washers. And all the rear sub frame bushes as well as the ARB bushes and drop links. I used Meley bushes everywhere i could and the car feels amazing now. The rear feels great but i did also put in a LSD but that wont help the problems you have described. I have Meley control arms track rod ends and drop links out front. But polly bushes in the lollipops and ARB I will change those when i can i think. If you want a good upgrade in the front. Put an M3 anti roll bar in cheap as chips and made a great improvement.
 
Meley bushes?!?

I dropped the complete rear axle and changed all bushes (all 19) for poly in about 3 hrs, and I did things easy, in my own time... So thats about 10min per bushing. Easy job if you have the right tools.
Fiddeling with the handbrake and removing the exhaust are the difficult parts (they can be) when dropping the rear axle.


What to change?:
If your car has significant mileage change everything which is easily accesible. All rubber parts (if not poly) and ball joints are wear parts.

If you want to have a comfortable drive around a dirt track: buy another car. A z4 will never be comfortable on those bumps. It's a sportscar.

Conquistador said:
Looking at the Powerflex website, could you offer some preliminary guidance on which of the following I would require if I did go poly?
Click to expand...
Powerflex doesn't have all the required bushings.
Some you have to get at http://www.strongflex.eu/en/
bushings from strongflex a bit cheaper than powerflex and you can choose the density (shore 80A or 90A, and powerflex is 80A (Except the black bushings, they are 95A))
For the lower track arm outer bushing get an extra upper track arm outer ball joint. That fits (the z4m uses the same combo), and the strongflex bushing for that spot doesn't fit properly.
 
Machine monkey said:
Put an M3 anti roll bar in cheap as chips and made a great improvement.
Click to expand...

Thicker ARBs make your suspension less independent - not good when considering suspension articulation on poor roads.

If the OP did this, and fitted coilovers, it would allow him to run them softer, and still obtain a solid feeling from the front end.
 
Watching this thread with interest as my rear suspension has started creaking and banging recently.
 
TheHoff said:
If the OP did this, and fitted coilovers, it would allow him to run them softer, and still obtain a solid feeling from the front end.
Click to expand...

I don't think that there are many coilovers that are softer than the stock springs.
 
GuidoK said:
TheHoff said:
If the OP did this, and fitted coilovers, it would allow him to run them softer, and still obtain a solid feeling from the front end.
Click to expand...

I don't think that there are many coilovers that are softer than the stock springs.
Click to expand...

I meant that they could be run comparitively softer than other settings available on the coilovers.

You can however specify spring rates, to which the dampers can be matched, on many coilovers these days.

A properly setup, setup, will yield the best results too - geometry can play a significant part on whether a car negotiates bumps correctly/comfortably or not.
 
You must log in or register to reply here.
Back
Top Bottom