I Tested My Mods and Set a New Track Baseline in My BMW 128i
Finally, a fulfilling culmination of a few months’ work.
After blogging at length about every development with my 2011 BMW 128i since I bought it in March, I finally have solid proof that it's all been worth it. What started out as an Alpinweiss blank canvas has evolved into a magnificent Caspar David Friedrich piece that has a blissful exhaust soundtrack, better seat retention, confident cornering grip and turn-in thanks to a good alignment, and a more planted ride.
This project has come together nicely and is now much more suited for trackwork. I recently tested out the upgrades at a track day at Willow Springs International Raceway's Streets of Willow circuit north of Los Angeles, and I was extremely happy with the results.
Shortly before I headed north to Willow Springs in California's picturesque Antelope Valley, I threw on a set of track-worthy wheels and tires that R Compound USA put together the day prior. The wheels are anthracite Apex Race Parts' ARC-8 in 17x8.5 ET40, which are wrapped in 235/40/17 Accelera 651 Sport XTRAs. These meats are 100TW fare that I picked up on deep sale (to the tune of $92 per tire) from TireStreets.com, whereas the wheels are 17.2 lbs each, which I special ordered from NextLevelRaceShop.com.
The idea behind throwing this package on was to not only reduce rotational mass/unsprung weight, but to also have a grippy tire that will stand up to the abuse of track driving, especially on a technical and sidewall-demanding circuit like Streets of Willow. The Yokohama Apex V601s that I had on my 128i's factory set weren't bad, but left a lot to be desired during my first run. Going with the 8.5-width wheel ensures I can mount up wider fare in the future, and, man, these things just look so good bolted up to the little coupe. Under no circumstance do they rub on the inside of the fender, too, which is a major relief—thanks, negative-camber-rich alignment!
Grasping New Concepts
With a trunk full of tools and fluids, I scuttled up to the high desert two Sunday mornings ago to put my more capable 1er to the test. During the first session on track heading clockwise, I had two high-speed curve balls thrown my way: The Accelera tires aren't very grippy, and I can't trailbrake the ever-loving crap out of the 128i like I could with my old Mazda 2.
The tires took a whole two laps to fully warm up, and even when they got there, they still didn't have a whole lot of grip. Especially for supposedly being 100TW, which is a pretty darn track-centric rating. But there is some good news. What grip there is doesn't fall off too bad, they're very predictable and communicative, and they barely wore down after a day's worth of turning laps. Because of this, as well as their immensely cheap price, I'll chalk this up as having good learner tires for getting used to my new Bavarian rear-wheel-drive (RWD) steed. It's better to burn these out while getting used to a new chassis than something that costs $70 more per tire, which is the floor for good 200TW tires in 235/40/17 or 245/40/17.
The second curveball was a bit embarrassing. I found myself washing out in understeer at Turns 2, 4, and 11—turns that I used to be able to slice right through in glorious 100-horsepower rage with my Mazda 2. I had to take a step back, say to myself out loud, "Show a little more poise and precision, dumbass," and do more of my braking in a straight line before turning in. I also had to smooth out my brake and gas inputs.
How could I forget that I had rear-wheel drive to help rotate me around apexes? Not only that, but I had all this glorious inline-six torque at my toes, and I was able to put it to good use and surpass 100 mph at times between Turns 8 and 9—I didn't need to trail brake the car.
Additionally, in my flurry of getting the 128 ready during the week prior, I forgot to throw the Hawk HP Plus pads back on, which came mounted up when I bought it and made braking zones stress-free during my first track outing. With these pads, I was able to brake late and into the ABS from 110-or-so mph as naturally as coming to a graceful, complete stop in a school zone. The Hawk HPS pads that I'd thrown on as a more daily-friendly option weren't horrible but had poor modulation and my braking zones were far longer.
The Game Plan Henceforth
My 128's current setup proved to be a solid track-oriented baseline. I kept the Koni Sport dampers' rebound set to full soft so I could enjoy a little less body roll but still feel out the other incremental changes, such as the better alignment and more track-worthy tires. Plus, this was only my second outing with the 1er—I should put more seat time in before going hog wild with future mods and adjustments.
I'll need better pads next time, plus I'd appreciate a firmer pedal, so stainless brake lines are on order. It's already got good brake fluid coursing through its system, but it's not as good as Castrol SRF, so that's on order as well.
The alignment was nothing short of stunning on Streets' technical tarmac. As long as I drove the car correctly, it only exhibited oversteer when I wanted it to, or when the tires started to fall off slightly at the end of each session. Turn-in was sharp and confident, cornering grip was excellent, and it felt overall more stable at speed. Especially while negotiating Streets' gnarly chicane between Turns 9 and 11. I'll try to pay a visit to Chewerks before my next trackday to ensure the specs are still looking spiffy.
The 128 was also noticeably slower up the front straightaway later in each session, which could be due to the buzzkill coding that lives in its DME (what BMW calls ECUs). This coding is known as Engine Power Reduction to Prevent Brake Disc Overheating, possibly also Brake Fading Compensation. Even with coolant temps well below 230 degrees and brake pads that were a cut above OEM. I finally have all the resources needed to code all of this out, by the way, so look forward to a future blog on that.
My times were consistently faster than I could lay down in my Mazda, but only by 1.5 seconds or so, which is far too slow for this car. My best was a 1:34.22, but I should've been doing at least 1:32s, even with the brutal ambient high desert Summer heat. With that, better braking, more seat time, a little messing around with a laptop, and possibly some rebound tuning are in order before and during my next visit.