Z4M - Suspension Help

I had Eibachs and standard shocks for quite a while. The car was better controlled on track than with OEM springs, but pretty awful on bad tarmac. Mostly the problem was tramlining, rather than the crashy ride per se. Whilst the Eibachs fixed the front end lift at speeds over about 120mph, the car still tried to understeer when turning in to low and medium speed corners.

I changed them to KW Clubsports more than ten years ago, and it was a revelation. The car now handles beautifully and remains balanced transitioning from braking to turning in, as well as when applying power and exiting corners. Overall the mass of the car is much more controlled, so it turns rather than pushing on (eliminating understeer was something that I couldn’t achieve with geometry changes with Eibachs and OEM dampers). My braking distances markedly reduced too because the car no longer pitches under hard braking.

However….they definitely do not make for a pleasant ride on the road. My teeth are broken from running over painted lines and my spine crumbled to dust years ago :D
 
I started reading your post and thought great, just what I want - then I got to the 3rd paragraph and realised it isn't! :lol:
 
Mr Tidy said:
I started reading your post and thought great, just what I want - then I got to the 3rd paragraph and realised it isn't! :lol:
Click to expand...

They’ll be perfect for you, so long as you mount the driver’s seat on ‘helper springs’ and take a cushion with you :D
 
Mr Tidy said:
I've spoken to a couple of M owners who have fitted Eibach springs then removed them again.

My car came fitted with H & R coli-overs and they are very crashy too.

Last year I was lucky enough to get a ride in a 20K mile MC on OE suspension and compared to my car it was like a magic carpet ride, so if/when I change I'll stick to OE springs - not sure about dampers though.

But as my H & Rs have only done about 20K I can't get my head around swapping them yet, even though I often also cringe quite often when I hit a bump.
Click to expand...

If you still have the OE springs, I would just go with the B6 - this is the most economical way and should get you back to close to OE. I had a chance to ride in a car with the B12 setup before deciding on B6 with OE spring. The B12 have basically took out all the travel at the front and the Z4 had very little to begin with. Almost went with the B16, but I didn't even want that little drop that it provided.

You won't have much choice on dampers for the Z4M, unfortunately. It's either Bilstein B6 or OE, which is about 3x the price the Bilstein...if you can get your hands on a set. At that price point of the OE dampers, you might as well go KWs!
 
I had the same decision process. B12 vs B16 and went for the cheaper B12. Unfortunately I bought the Z 10 years ago when it had OE shock plus H&R springs so don't have the OE springs. I'm thinking though OE springs is the way to go with the B12 shock rather than the B16 setup. I'm heading towards 60 next year so comfort starts to make itself a priority over handling (well relative comfort for a Z) and as long as I can get in and out of the Z it's staying. 🙂
 
I found that the Eibachs made no significant difference to the ride in my Z4MC with 95k mile old shocks. The ride was quite decent and car handled OK.

I aligned it after the Eibachs and so can't attribute the improvement in handling just to that. But Eibach with a proper alignment was a non compromising upgrade to the handling. Always thought comfort was OK.

Now the custom BCs I've fitted improved all aspects of the ride and handling. Happy to take Z4M owners for a passenger ride if you're around Northamptonshire.
 
I've no doubt that new BCs are an improvement over new OEM, but new OEM will be vastly better than 95k old OEM :D
 
I've been trying to figure out the best combination for an OE factory 07MC ride. I have 113K on it, but don't know what these cars rode like when new. It still has the OEM springs and struts/shocks installed. Based on what I'm reading, stay with OE springs & B6's and that should get me as close as possible to the OEM ride, w/o the OEM strut price.
 
the issue is the lack of data, there isn't shock data on B6 or OE, but we know the construction is different, and the B6 being monotubes have higher gas pressure and will be harsher. If you want OE like ride, get OE.
 
OEM front struts are $1200 without any other supporting parts. That seems pretty high IMO. I wonder how much difference they would make over the current old OEM struts?
 
I just went through this exercise a few months ago. For a street driven car, I didn't noticed any more harshness with the B6 compared to the OE dampers. I've owned the car since 7400 miles and just swapped dampers out at 70,000 miles...so I'm used to how the car feels. IMHO, If you want to keep the stock feel and ride heights, then B6 dampers and OE springs is your only option with the Z4M (other than OE), unfortunately. All coilovers require a minimum drop in ride heights, which will lose more travels that these cars have very little to begin with.
 
XMetal said:
All coilovers require a minimum drop in ride heights, which will lose more travels that these cars have very little to begin with.
Click to expand...
You can comfortably run OEM ride height, or higher than OEM, on BC coilovers.
 
XMetal said:
I just went through this exercise a few months ago. For a street driven car, I didn't noticed any more harshness with the B6 compared to the OE dampers. I've owned the car since 7400 miles and just swapped dampers out at 70,000 miles...so I'm used to how the car feels. IMHO, If you want to keep the stock feel and ride heights, then B6 dampers and OE springs is your only option with the Z4M (other than OE), unfortunately. All coilovers require a minimum drop in ride heights, which will lose more travels that these cars have very little to begin with.
Click to expand...

Good first hand information! Thanks XMetal! :driving:
 
plenty said:
XMetal said:
All coilovers require a minimum drop in ride heights, which will lose more travels that these cars have very little to begin with.
Click to expand...
You can comfortably run OEM ride height, or higher than OEM, on BC coilovers.
Click to expand...

Thanks - good to know for future reference :thumbsup:
 
You must log in or register to reply here.
Back
Top Bottom