PARTS:
For a long time I've gathered the M3 bits, and after careful consideration (see
here) I added an upgraded spring & shock combo. Below is what went on the car:
- M3 Front Wishbone Set
- M3 Front Tension Strut Set
- M3 Aluminum Rear Guide Rod Set
- M3 Aluminum Rear Wishbone Set
- M3 Front Sway Bar Kit
- M3 Rear Sway Bar Kit
- M3 Rear Subframe Bushings
- BMW Performance Springs (yellows) with correctly paired bumpstops (part of the v2 kit)
- BMW Performance Dampers (v1 kit)
All except the bushings & bumpstops were used. For the record: M3 bits had 3.5-4k miles on them, dampers & springs were luckyu's and had 7150 & 5080 miles, respectively. A big thanks to cvc for digging up the part numbers & a supplier for the bumpstops.
JOB:
I had the job done at a local shop (review
here). There is plenty of info on this forum about these parts so I'm not going to add to it. What I am going to add is something I could not find anywhere and had to dig into TIS to extract for this job:
parts that need to be replaced + the torque specs.
Find this info attached. And if you think giving these parts to your mechanic will get you the proper torque & all the correct parts replaced I think there is a good chance you are fooling yourself: It takes too much time to dig this info up for every nut & bolt, so I insisted to be there for the whole job exactly for this reason - to make this possible, to look stuff up and make available. Now I
know I have everything installed correctly.
After the install the alignment - esp the toe - was so out-of-whack that the car felt as if it rolled on eggs. You would turn the steering wheel a bit, the car would plunge wholeheartedly into the turn and you had to force it back under control. I went straight to have my alignment done, which made it driveable again.
+ a note: all the parts we took off - all were in great condition. We did not find any loose or stuck or damaged screws or nuts, and there was not even a small leak on the dampers @ 72k miles. All the control arm bushings looked ok, with no tears or damages. I think BMW really deserves credit for this in terms of a quality car & build.
IMPRESSIONS:
On first impression it felt really harsh. I am used to a hard suspension but this really felt rough. Turns out the miserable roads on the East side of town, combined with my tires inflated for over 100mph (35/41 psi), were to blame. Possibly the switch from all-season RFT 17's to summer non-RFT 18 might have helped too... too many variables. Anyway, after setting pressure back to stock 32/35 psi things are back to normal.
After the roughness was gone I was finally able to see if may
main objectives were met: reduce body roll, and more importantly lose the feeling I get when turning at higher speeds - that I might be sliding and losing control. It was a very unsettling feeling, felt like a part of the car was having a different dynamic then the rest of the car. Best I can described it is: oh-sh*t-I-think-I'll-lose-it feeling. And it got worse when I hit joints in the road, as I would wonder on each if I'll regain traction or slide out. It is not what I was expecting from a BMW. Happened on both my summer performance non-RFT's 18's and my "winter" all-season RFT 17's.
Well, I happy to report: objectives met ! Even with the sh#tty wet weather we had since, the car finally feels worthy of the BMW name, or least what I was imagining it to be.
There is a massive reduction in body roll that I attribute mostly to the bars, with the shock+springs helping too. And it is a very balanced handling not a sudden change from feeling understeer to oversteer or vice-versa. It's really a perfect balance, no chasing steering feel.
As for the 2nd objective - oh jeez, the car at last feels as if it's one piece with everything solid, planted, and working in unison. All parts feel connected and predictable, and it makes for a pleasurable drive. No more doubting the outcome of a turn.
BONUS:
On top of all this, the suspension feels more comfortable then the previous OEM sport suspension the car came with. I attribute this to the notoriously under-dampened sport dampers, so while the springs are now stiffer, because the dampers really slow the oscillation down you don't just thunk when a road event happens (bump or pothole), you actually get a gradual amortization of the wheel movement, not a free bang. I really think the sport suspension was a poser.
Lastly, as this is getting ridiculously long: on my commute, right before the Vista Ridge tunnel the road is really harsh and the vibrations get transmitted to the inside of the car quite intensely. Well, this morning I did not feel these vibrations reverberating everywhere in the car. Wow !
I have to think that I am probably in a bit of an owe because of all the upgrades I had put in at once. So maybe in time I will, like others, find things that could be improved, but as of right now it feels really great. The only thing I noticed is that I get a little more steering pull, but I'm not yet sure if it a case of tramlining or torque steer. Next project ? - likely...
