Our car needed new shocks.
A peek underneath our BMW 328i confirmed the situation: The dampers looked to be original, meaning they were nearly 15 years old and had 125,000 miles of service. While the car rode well and still handled decently, we were looking for a bit more of a premium experience.
We also knew that the BMW wanted more negative camber up front. Why? To flatten the tire’s contact patch through the turns.
The factory sets the negative camber on all four corners of this E90-chassis BMW at a safe, conservative half to a full degree. While that’s fine for grocery getting or driving to work, we knew that we wanted more–like 1.5 to 2.5°.
Just swapping in new shock absorbers wouldn’t add more negative camber. Lowering springs would add more negative camber, but they lack adjustability.
We needed adjustable front camber plates. While these can be purchased separately, what about buying a spring/shock package that included a set?
We’ve had a lot of luck with Konis over the years–they’re fast, comfortable and often a bit of a value buy–so we turned to its catalog. Its new GTS coil-over packages caught our eye: threaded damper bodies for lowering of 1.0 to 1.4 inch, adjustable valving, and front camber plates. This kit also uses fairly common 2.25-inch-diameter coil springs.
Tire Rack carries the kit for $2204.65, and it also offers a Koni Sport damper kit that lacks the camber plates and ride height adjustability for $1349.29.
Our goal was not to slam the car to the ground. We wanted a reasonable drop to the center of gravity plus the ability to corner-weight the chassis for proper balance.
[Understanding corner weights]
Installation was fairly easy, although we did have some clearance issues up front as the helper springs caused the threaded perch to contact our wider-than-stock tires. Removing those helper springs raised the threaded perch out of the way. The helper springs were there just to prevent rattling, and to date we haven’t heard any issues.
Another problem, though: Adjusting the front camber plates is a bit tough as the shock tower’s opening is tight and also covered by a strut tower brace. Our solution is to just move that brace out of the way when necessary.
Once we installed the coil-overs and set the ride height for a 1-inch drop all around, we performed a baseline alignment: about 1.5° of negative camber front and in the rear, 1/16 in toe-in in the rear and zero toe up front. Now to head back to the Florida International Rally & Motorsport Park, our official test track, with Tech Editor JG Pasterjak behind the wheel:
“Tires are typically the biggest performance pickup on most of our project cars, and this BMW 328i was no exception. Suspension improvements usually show marginal gains when bolted on, but their real benefit typically comes in added adjustability to better tune the car to a variety of situations.
This 328i, however, reacted very well to simply having the Koni coil-over kit bolted on and set up with a “best guess” alignment. And while the numbers improved dramatically, the subjective feel improvement was just as impressive.
Even with its worn-out stock suspension, the 328i showed exceptional poise and drivability. With the Koni kit in place, it still shows those benign tendencies, but now with some impressively high limits to match its ease of use.
Looking at the VBox data, if we examine the Delta T graph, which shows how much time is being gained or lost by our two highlighted laps–red for stock suspension with BFGoodrich Phenom tires and green for Koni coil-overs with BFGoodrich Phenom tires–we can see that the Konis saved time through almost the entire lap.
There are two small plateaus in acceleration zones, but pretty much anywhere the Koni-equipped car is braking, entering a corner, exiting a corner or moving through a corner, it’s picking up time.
Check out the speed trace just before the 2000-foot mark. That’s the entry to the FIRM’s fast, right-hand kink, Turn 4. The improved 328i is entering nearly 2 mph faster with its new suspension and holding that advantage through the entire sequence and down the subsequent straight.
Better pitch control is also showing up under braking at the next corner, around the 2300-foot mark. The deceleration rate of the 328i is now notably greater, and the longitudinal acceleration trace (bottom graph) is also much cleaner. Previously, the car needed lots of adjustment as it got to max deceleration and the bump stops engaged. Now it just stops smoothly, with max braking force sustained over 1g.
Cornering power is also improved, and we can see this dramatically in Turn 5 and Turn 6, which are around the 2700- and 3300-foot points. The Koni-equipped car enters the corners faster and maintains more than 1g of cornering force to the exit point.
These corners also start to show how the grip is starting to overwhelm the BMW’s relative lack of power. We see only modest speed gain from Vmin during the cornering phase because the tires are so heavily loaded laterally, even though we were definitely transitioning to full throttle as soon as we got to the apex.
Only once we start to seriously unwind the steering do we see notable acceleration return. It’s a tendency of underpowered, over-gripped cars, but one we’re happy to live with because it tends to mean we’re maxing out some of the most enjoyable characteristics.
In the case of this 328i, switching to the Koni coil-overs netted us a little more than 1.7 seconds, dropping the car’s best time from a 1:27.43 to a 1:25.69.
There’s more time out there, too. The chassis is still working the outside edges of the front tires pretty hard, so perhaps a bit more negative camber would square up those contact patches a bit better. Still, considering the comfort along with the performance improvement, we could do nothing more and have a perfect dual-purpose machine."
