M135i | B12 Pro-Kit | Bilstein B8 Dampers & Eibach Springs

B12 Pro-Kit - Bilstein B8 Dampers & Eibach Springs
If you read my previous post, you'll be aware that I recently purchased upgraded shocks & springs (B12 Pro-Kit Autodoc) for my m135i. 

The kit was fitted last Thursday and I've had a full Hunter alignment + wheel balancing.


B12 Pro-Kit £538
Fitting £80
Align £60 & Wheel balancing £30

Useful info 

Std m135i ride height...
- Front 352mm
- Rear 370mm
- Difference front vs rear: 18mm

B12 spring rates... 
- Front 120 lb/inch
- Rear 384 lb/inch

B12 ride heights...
- Front 343mm (9mm less vs std) 
- Rear 353mm (17mm less vs std)
- Difference front vs rear: 10mm


1. The lowering offered by this kit is nice and subtle - certainly not the "boy racer" look (for e.g. H&R springs look too low to me)

2. Limited loss of uniformity between the line of the wheel arch and the line of the wheel (the lower you go the worse this issue becomes)

3. No scraping when getting on/off my driveway

4. No issues with speed-humps

5. Reduced rake (diff in height front vs rear) compared to both the standard setup and other kits on the market

High Speeds

Previously if doing 100mph on a carriageway, the car used to feel really light and floaty, and the steering wheel used to twitch as you hit surface imperfections or when the camber of the road changed. This is no longer the case. At high speeds the car now feels solid and planted. For me, this is definitely one of the biggest benefits of the upgrade. 


The car now squats down at the back much less when you put the power down, resulting in the front-wheels and steering now both feeling less light. Generally the front-end of the car feels more positive and much more "connected". 


Before, if I hit a big pot hole, the car would make an awful crash - so much so that you'd think you broke something or split an alloy. This is now gone. You still hear a thud (as you would expect with any form of sport suspension) but it's a healthy sounding thud - you're no longer left wondering whether your car is still intact!


The car is now a dream in the corners. It corners flat - there's no longer excessive leaning or wallowing, and this gives you increased confidence in the bends. The ride is firm (no firmer than std) yet it's much more comfortable than the std setup. On broken road surfaces and patchy gravel, there's also no noticeable increase in Noise, Vibration or Harshness (NVH).


I'm absolutely ecstatic at the difference this upgrade has made and I'd highly recommend it to anyone who owns an m135i/m140. 

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