Photography by J.G. Pasterjak
In January of this year, we had no real idea we’d be doing a late-model BMW project. Ten short months later, we’re loading it up on the trailer to head to its first SCCA Time Trials Nationals in Bowling Green, Kentucky, after a season of mostly successful and trouble-free track use. (Well, after a few things that broke.)
[Surprise: Our BMW 435i broke a belt during its first track day]
And the thing we’ve learned this week as we’ve prepared for our first season finale with the car is that hurricanes really screw with your preparation plans.
Originally, we had planned a final track day at the Florida International Rally & Motorsport Park to properly heat cycle a set of tires and run through some proper testing on our new CSF front mount intercooler. We’ll discuss the piece and the install in the future, but the bottom line is whenever we open the boost circuit, we like to do some torture testing to make sure it’s been properly closed.
Sadly, a massive, swirling force of atmospheric fury named Milton threw a wrench in those plans, and not the good kind.
Now, look, we’re not comparing the plight of our silly BMW track toy to the absolutely real and horrific devastation our state has now experienced twice this fall, or the unimaginable horror that another one of our tropical friends wreaked on Appalachia, but we did have to do some improvising in the face of adversity. All we really lost were a couple of carports attached to our shop but, perhaps more importantly, we lost several days of prep time due to no power.
So we had to make some adjustments to our plans, but hopefully we came as close as possible given the situation to our intended prep level.
Our biggest regret was not being able to properly dynamically heat cycle out new Bridgestone Potenza RE-71RS tires. Our original set had done well by us, making north of 150 laps of the FIRM, Daytona and VIR, as well as doing a couple thousand miles of street duty. They still had measurable tread, although the center ribs were starting to chunk up a bit and the shoulders were becoming increasingly rounded.
So a new set of Bridgestones were mounted up on our BendPak tire machine–where we promptly broke a TPMS sensor. Yeah, that’s the other thing that sucks about lost time: Mistakes have a way of becoming that much more annoying.
[Does investing in tire mounting equipment actually save money?]
Luckily our friends at BimmerWorld shot a sensor down to us overnight–fewer than 24 hours after we called them it was in our hands–and got us back on our now-compressed schedule.
But the question about heat cycling remained. We just wouldn’t be able to do a proper dynamic cycle, so we tried to do the next best thing: We heated the tires in our Chicken Hawk Racing tire warmers to around 170º Fahrenheit and then immediately went for an hourlong drive on the highway.
Heat cycling a tire is about much more than simply heating and cooling the rubber. Ideally, you want to heat the tread and sidewalls while also putting physical stresses into the tire to temper the tread by dynamically aligning the granular structure of the rubber. This typically results in more consistent wear and performance.
[Heat cycling: The secret to tires that go faster and last longer?]
Heating the tires with the blankets just gave us a bit of a head start on the dynamic portion of the process, and the extended highway drive, where we hit a couple cloverleafs of both directions, let us put some side load into the rubber, although certainly not track-level side loads.
Was this as good as a proper dynamic heat cycle where the tires are allowed to build to temp over a few progressively harder laps before cooling completely overnight? No. Absolutely not.
Was it better than simply throwing them on and sending it? Yes.
Was it the best we could do given the reality that confronted us? Also, yes.
Sometimes you play the hand you’re dealt, and this was our way of trying to take something out of the pot with a King-Ten offsuit.
With the tires out of the way, the rest of our prep consisted of fresh Hawk DTC-60 pads. Our previous set of DTC-60 pads had worn from their original 12.5mm thickness to around 8mm and still produced plenty of stopping force and zero fade.
We did get some pad knockback, though, due to the thinner pads having more room to push away from the rotors. That old set will now get put into backup duty while a fresh set of DTC-60s will see primary track duty.
If you’re keeping score at home, that brings our consumable totals to one set of pads and one set of tires for 10 months of heavy track use. And both could have easily gone longer, although not at peak performance.
That’s a pretty mild use curve for a 3600-pound car. It would imply that the car is fairly well balanced, and that our initial fears about the rear e-diff–which jiggles the rear brakes to create a faux LSD effect and can lead to accelerated pad wear–were overblown.
We also did a quick brake bleed with Red Line RL-600 fluid. The car had been flushed and filled with RL-600 back in March, and was still showing 0% moisture in the fluid, which still looked new, so we didn’t bother flushing again.
Aside from that, a trip to the car wash and some new number panels for the event, we’re good to go.
Oh, pro tip: We stuck those numbers on a panel of Oracal 631 vinyl that we ran over the whole bottom part of the door. The 631 is Oracal’s “removable” option, and while it provides good adhesion, it does come off with relative ease and doesn’t break up into tiny bits when you peel it. This gives us a nice big spot to put the many event-required decals we’ll have to run at TTN, then lets us peel them off with one swipe after the event.
[How to properly apply vinyl stickers to a car]
And with that, we’re on the trailer and ready to head north. We’ll be competing in the Tuner 3 class, for which we’re not prepared anywhere near the limit of the rules, but it should provide a nice baseline as we continue to develop the car. Many of our modifications this year, like our oil system revamp, have been in the name of durability, not speed. But they’re also mods that bump us up to a more highly prepared division like the Tuner spec.
But while those mods don’t provide any speed on their own necessarily, they do make adding that speed far less likely to have disastrous consequences.
So now that we’ve got reliability out of the way, we can start focusing on things like intake temps and boost and freeing up exhaust flow and a more sophisticated suspension approach without fear of hurting something.
For this year, though, we’re just glad to head to the event, even if we had to improvise a bit to get there.
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