Suspension choice

[Andrew517]

Hi there!
I would like to ask if it is okay to fit the M Sport suspension strut with BMW Performance Spring coils? I currently using BMWP suspension kit, it has been using over 10 years, and I think it is time for me to think about it. Thank you !

[fast1eddy]

You could but you would be better off with Koni Sport or Special Active. I have Special Active with Mperformance springs and I'm very happy with the overall performance.

[Olgeezer1]

Either Koni or Bilstein will be an improvement. 1 series shocks/ struts, being BMW'S cheapest car, did not get their best components. All factory BMW springs work well with what used to be called H.D's (B6 ). If you lower more than 25mm. (1"), which Performance springs don't, then you want the B8's. Been on B6 with stock Sport Package springs for years, no issues, work great.

[Papa Popov]

Originally Posted by Olgeezer1

Either Koni or Bilstein will be an improvement. 1 series shocks/ struts, being BMW'S cheapest car, did not get their best components. All factory BMW springs work well with what used to be called H.D's (B6 ). If you lower more than 25mm. (1"), which Performance springs don't, then you want the B8's. Been on B6 with stock Sport Package springs for years, no issues, work great.

IIRC states B8s are for "lowering springs" since the length of the damper is shorter. Jury's been out for years on Bilstein defines as a lowering spring and when asked directly they've given conflicting answers. The fact that there are sport and non-sport springs only adds to the shitshow.

Eibach springs list a drop of 1.2" (from non-sport springs), which ends up being less than 1" (and varies based on the spec of the car) if swapping from sport springs (which all 135i came with AFAIK), yet Bilstein still went with the B8s for the B12 kit. So if we apply the >1" lowering rule we should use the drop from non-sport ride height? Or are the B8s appropriate for a <1" drop like the other half of Bilstein marketing material claims? No one, including Bilstein, knows apparently. Same applies for BMWP springs, which claim a (significantly more consistent) 25mm/10mm drop for non-sport/sport respectively.

I dug through years worth of threads full of bickering over this topic when I was looking for dampers to go with my BMWP springs. There's no clear answer and I found plenty of people running both B6s and B8s w/ BMWP springs. I went with B8s because I found more reports of people happily running B8s, and at the time (mid-2020) it was damn near impossible to find B6s or B8s outside of the B12 kit. When I could find either option they ended up being about the same cost as the B12 kit, so I figured I might as well get some free springs to resell.

@OP, I wouldn't run stock M-sport dampers with BMWP springs as they'd likely be too compliant with the stiffer spring. For the Bilstein options, I don't think you can go wrong with B6s or B8s.

[ShocknAwe]

Bilstein plus springs or switch to something proper like Ohlins. I had a lot of configurations over the years and those were the best.

1er has a chassis which is too short unfortunately and this requires a lot of suspension tuning to get right.

[ShocknAwe]

Another note my experience was <1" do B6 and >1" drop do B8. If going Koni on this platform I'd go wi to h a built setup like TCK, the Koni yellows are inferior.

[Pistolpete2911]

Originally Posted by fast1eddy

You could but you would be better off with Koni Sport or Special Active. I have Special Active with Mperformance springs and I'm very happy with the overall performance.

I was thinking about installing Koni special active but with Eibach Pro kit springs.
How much do the Mperformance lower the car?

[asbrr]

Mperformance drops 10mm from M-Sport. Eibach Pro-Kit is another 10mm on top of that approximately (slightly different 135 vs 128 etc).

[fast1eddy]

Originally Posted by Pistolpete2911

I was thinking about installing Koni special active but with Eibach Pro kit springs.
How much do the Mperformance lower the car?

The special active work best with minimal or no lowering. Lowering too much puts them out of the active range.