TrackSTer – Suspension
We named this thing TrackSTer. Because we drive it on the track. Get it? Well, of course there’s more to it than that, since from the beginning we knew we didn’t want to build an all-out race car. As cool as building a dedicated track car would be, it didn’t really fit the scope of Project-ST as a whole. Sure, some of you probably will turn your Focus STs into true race cars, but the majority of ST track enthusiasts are looking at a weekend track day kind of proposition. So with TrackSTer we knew that keeping our project not only street-legal, but also street-usable should be a top priority. To us this meant no rear seat killing roll-cage, no engine mods/open exhaust set-ups that would make the car a chore to drive on the street, and of course – the subject of this article – we wanted a suspension system with an adjustment range that could go from (sorta) mild to wild. So to speak.
From our time spent working on the Focus Block STyle suspension set-up we became quite familiar with Germany’s world-renowned suspension manufacturer, Eibach, and more specifically their US operations in Southern California – a mere 40 miles or so from our downtown LA facility. How convenient, right? So before we even got started on the build we had a quick meeting with good friend and Eibach’s Private Label Manager, Ryan Hoegner, and we explained our goals to him. Ryan suggested we go with one of their Multi-Pro R2-based coilover kits, due to the fact that they have separate compression and rebound adjustment, remote reservoirs for additional heat resistance, and he told us we could even choose our own spring lengths and rates, as well as the overall shock damping range. That last part hooked us big time, since the thought of having access to Eibach’s engineers and manufacturing facility while customizing our own super-high performance coilover kit was pretty much a dream come true for a group of gear-heads like us. And with Ken Block and the engineers from Mountune offering input, this collab had can’t-miss written all over it. The experience was amazing and we’re so pleased with the results that this one-off TrackSTer kit has morphed into the prototype version of our upcoming f/RP Mk3 Focus ST ultra-performance coilover kit (more on that later).
The Eibach Multi-Pro R2 kits use a stout monotube design and a threaded stainless steel shock body that allows for easy height and corner weight adjustment. Upper spherical “pillow-ball” upper bushing mounts decrease steering and suspension reaction times, while providing an increased level of feedback to the driver. The remote reservoirs use stainless steel and Teflon braided lines, ensuring durability and protection from chafing during extreme conditions. As mentioned, a variety of different spring rates and lengths were available to us.
To begin we had Eibach engineers show us how they go about prototyping a new application. Typically, Eibach will baseline the OE spring and damper rates. Then, depending on the kit designation (R1 or R2, for example), they will add about 30% to the OE spring rates. Based on those numbers they will choose damper configurations they believe will have the best operating range when used with the proposed spring rates and lengths, and then they will measure the performance of both spring and damper together (see attached graph for illustration). How the kit will be used (mainly street or mainly track) factors heavily into the damping ranges chosen. Once a prototype is assembled Eibach engineers install the kit on an actual vehicle and then put in hundreds of miles of street and track R&D. Eibach will continuously work with different spring and damping rates until they believe they’ve come up with an ideal – real world – combination.
With the TrackSTer we asked Eibach to add a little extra spring rate to the rear, as we’ve seen that on the track these cars benefit from extra rear roll stiffness. Because we plan to add custom front lower control arms (longer, and with revised ball-joint geometry), we also chose to go with a slightly shorter spring length all around, with the idea being that we will be able to lower our center of geometry without introducing any extra bump-steer to the equation.
With a prototype R2 kit assembled we went quickly to the install process. We knew the Chicago Auto Show was fast approaching and we wanted to have time to shake down the car at our local road course (Willow Springs). Installation was very straightforward with the only real challenge being where to mount the remote reservoirs. The main goal is to avoid mounting them anywhere they might be exposed to potential damage, or to have the braided lines chafe against moving parts. We found a fairly logical place along the engine compartment’s rain tray and though some minor trimming to one plastic cover was necessary, so far we’re quite happy with the results.
You’ll notice there are no photos of the car getting corner balanced, and that’s because we have yet to do so. We’re still waiting on the previously mentioned custom lower control arms, and we will also add upper adjustable caster and camber plates. The car is currently aligned to factory specs with as much negative front camber as we could force (which wasn’t enough to save the outer sections of our poor sticky Pirelli P Zero Trofeo front tires after a half-day track session).
Though we didn’t get time before the Chicago Auto Show for a proper shakedown, we did find an excuse for some track time when Ken Block was in town shooting an episode of the popular Octane Academy TV show. Which took place at Willow Springs. How convenient. So KB grabbed the TrackSTer and we followed along in the Focus STanced.
Not having optimal alignment specs for track use, we expected our custom coilover kit to possibly somewhat disappoint. But it didn’t. Sure, turn-in wasn’t as sharp as we’d like and the car did push a bit at times (especially when the tires got hot), but with minor experimentation with front and rear damping rates, we’re convinced we and Eibach got it all right first try. KB instantly felt at home in the car and was very impressed with the car’s balance in the trickier sections, as well as how well it rotated in the corners and its consistency over several consecutive laps. Of course we agree with everything Ken said, and we had a blast with the TrackSTer over several hours of steady lapping (we had to leave at one point to refill the fuel tank).
So TrackSTer impresses on the racetrack – no surprise there, right? But how does it fare on the way to the track? Is it loud? Does it crash over expansion joints? Catch air over larger bumps? The answers to those questions are: not really, no, and no. With pillow-ball upper front strut mounts, there is a bit of extra suspension noise at times, but it’s not exactly a fair question since it’s the Mountune 3-inch exhaust note that always takes center sound stage. Also, the increased steering feedback those mounts offer, in our opinion, is welcome additional NVH (auto lingo for noise, vibration and harshness). As for expansion joints and road bumps, we’re honestly extremely impressed with the car’s ride quality – it truly is in the livable range when it comes to random street driving. Sure, coming off the track we soften the damping adjustment just a bit, but it just goes to show that even with very high-rate springs, as long as your dampers are properly suited, acceptable ride quality can still exist hand-in-hand with hardcore performance.
We’ve got more track time scheduled soon (for all three cars, actually) and we’ll make sure we update this article with a really kick-ass photo gallery.
As a footnote to this article we want to mention that we’ve so enjoyed our time spent with Ryan and his Eibach engineers, and we’ve been so impressed with the result we’ve achieved from working together, that we’ve decided to have Eibach assemble three different fifteen52-branded coilover systems for the Mk3 Focus ST. The TrackSTer kit seen here will go into production as the fiteen52/Eibach f/RP kit.