A Custom Alignment Gave My BMW 128i More Grip and Stability
Stringing together a formula of performance-oriented caster, camber, and toe settings transformed my 1er’s handling.
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After successfully bolting up some fresh new springs and dampers to my BMW 128i, it was time to seal the deal and get the car properly aligned. This would be the first time I've taken a rear-wheel-drive car with a fully independent rear suspension to get an alignment. To get the most out of my enthusiastic new spring and damper package, I decided to forgo a conventional alignment that ensures everything's within the manufacturer's specifications and instead opt for something that will highlight the chassis' steering and handling qualities on fun mountain roads and on the track. Therefore, a custom alignment was in the cards.
I drove out to La Habra, California, and paid a visit to Chewerks, a shop that specializes in suspension setup and alignment for track work. These specialists are no strangers to maxing out negative camber (we’ll explain these terms further down) or digging into the finer details like factoring in driver weight and preferred tire pressures. They're also familiar with the E8X and E9X BMW platform. The owner Rob Choo has aligned countless steeds just like mine and is a proud E92 M3 owner to boot. He takes your track goals and aspirations into account and comes up with an excellent recipe for handling perfection. For such services, I paid $150 out of my own pocket.
Performance alignments aren't for the faint of heart. The more aggressive and track-focused the alignment is, the more of a pain it'll make driving the car on a daily basis, plus it will accelerate tire wear at a faster rate. The more negative camber that cars have outside of the manufacturer's recommended spec, the more the car will tramline and follow road imperfections. Straight line acceleration might suffer a tad, too, as will fuel economy. Furthermore, if you don't keep an eye on tire rotation, the rubber will wear unevenly across the tread pattern.
Caster, Camber, and Toe
For a full understanding of how these alignments work, it’s important to know the meaning of caster, camber, and toe. Our colleagues over at Donut Media did a brilliant video that describes them with some solid visuals. As a crash course, negative camber is when the top of the wheels point more inward toward the center of the vehicle. Positive camber is, well, the opposite, as well as the opposite of handling fun. Toe-in and toe-out indicates where the tires are pointed —think of looking at your own toes aimed straight ahead, and then turning them slightly inward or outward. Caster angle is the angle of the strut mount in relation to the lower ball joint. Positive caster aids front-end stability and helps the front wheels return to straight after turning.
Generally speaking, the ideal performance alignment for me is zero toe (so the wheels are aimed straight ahead), negative camber (top of the wheel angling toward the car), and positive caster. Zero toe ensures an evenly dispersed load across the tire tread under cornering and improves responsiveness. Negative camber does the same and aids turn-in and cornering grip. Zero toe and negative camber also make the inside front wheel more upright and in-contact with the road under cornering. Positive caster improves responsiveness, tracking, and increases steering angle. Toe-out can be good for turn-in as well but makes the car a bit twitchy. Camber and toe can vary depending on the car, the type of motorsports activity, the track it's driving on, as well as what direction it's driving on said track. But for a generally good daily performance alignment, this will work for me.
Of these, BMW enthusiasts (including Choo) seem to agree that BMWs love negative camber. This is because there's just so much weight up front. Well, actually, there's a lot of weight in general, which is why these things are solid and stable on the highway. Adding more negative camber helps turn the heft and vastly improves cornering grip.
Details on My Setup
Shortly after I first picked up my 128i, I took it for a spirited spin through Angeles National Forest in the mountains north of Los Angeles. It generally did well, but I noticed that the front tires quickly became overwhelmed, and the steering felt a tad too sluggish for my liking. These issues became immensely more apparent during my first time behind its wheel on track.
Two months later, I was sitting in the 1er while Choo was underneath making adjustments with his complex system of lasers and gauges. I had installed Dinan camber plates that add 1.4 degrees of negative camber, and the previous owner had installed E9X M3 lower control arms that give it about a degree of negative camber. I'm now at 2.2 degrees of negative camber on the driver side and 2.4 degrees of negative camber on the passenger side. Toe is set to zero, and front caster is 7.1 degrees on the driver side, 7.3 degrees on the passenger side.
The reason for me to sit in the car was to fine-tune the alignment as much as possible. I even had just less than a half tank of fuel in the car, which is the amount I typically start out with before heading out for a session on track. No alignment figures are static: They're all affected by load and the transfer of load. To make the most of a performance alignment, factoring in driver weight is crucial. Choo also added a little more toe-in for the rear wheels, as this aids in stability under cornering and braking. Personally, I'd like a tad more squirreliness in a torquey rear-wheel-drive coupe's rear tires, but it's probably better to find that in an aftermarket differential instead. Plus, ya know, I've only tracked this Bimmer once so far… baby steps.
Unfortunately, I didn't know the car's alignment specs before swapping the suspension, and the swap threw everything hilariously out of whack, which is why you must always have the car aligned after changing suspension. Thus, it was prime time for me to get it all tuned up for massive cornering fun.
The Benefits and Downsides
I haven't tracked the car since swapping the suspension and getting the alignment, but I’ve already noticed the difference during daily driving. You feel the improved turn-in, the car feels generally more stable, and it only wanders a tiny bit on the highway. It actually reminds me of how the 2021 Lotus Evora GT rolls down the highway from the factory. As long as I keep my hand on the wheel, it's fine, and the tires never grab and jerk the wheel out of my hand.
However, these new specs shine in the corners. My God, does the 1er feel so much better. That improved turn-in and stability feels absolutely wonderful while upping the pace, and there's a lot more cornering grip in the front end. The rear end is generally more stable and planted across the board, too. The front end feels far less lazy, steering feels lighter and more eager, and I'm still on the bubbly 225/45/17 Yokohama Apex tires on stock 17X7 alloys. Imagine how much this will all improve on lightweight aftermarket wheels and stickier tires with a firmer sidewall? I can't wait.
So far, I can't really identify any downsides, probably because this alignment isn't overly aggressive. I'd call it a good all-around setup for someone who wants grip, stability, and response in all forms of driving. I haven't noticed any significant change to tire wear yet, as I've only traveled around 200 miles since my visit to Chewerks. It helps that I work from home and mix up my mileage with press loans from time to time, but I'll definitely keep my eye on wear and will rotate tires frequently.
This new advancement has me excited. After years of pulling as much negative camber as I could with my Mazda 2 for improved track dynamics, this is the first time I've had such an alignment on a rear-wheel-drive car. With torque, too. I'm stoked on how much progress I've made to uncover a playful little Bavarian coupe that yearns to get tossed around on track, and giving it a proper alignment is a massive step forward in doing so with ease.