Article by Brian Hannon. Photography by Ryan Randels.
And we’re back! Though Mother Nature didn’t cooperate for TX2K14, it didn’t dampen our spirits because we knew back home some good things were happening with Project BRZ. We’re back into the mix with our weekly documentary of the progress. To bring you up to speed, the engine is off to the machine shop where they can work their magic and we’re waiting on the remainder of the build’s components to arrive, including the widebody parts that we just finished up sourcing.
Two weeks ago we tore down our FA20 (4U-GSE in the Toyota / Scion world) and did a full assessment of all components from a performance standpoint. We found a focus on cost and efficiency but that didn’t keep Subaru from pursuing performance by cramming in a lot of technology like direct-injection and adjustable cam timing.
In this installment we crack open the box of our new Air Lift Performance Digital Combo Kit suspension and let you know what we found, compare and contrast to the stock suspension, and provide an initial assessment.
SCR Performance will be doing all the performance & suspension work, so we unpackaged the kit at their shop and talked with Mark Baer, owner and suspension guru to assess the kit and how it applies to the platform.
As we’ve done in previous articles, we’re first going to take a look at the stock configuration of the BRZ/FR-S and in this weeks case we’re focusing on the suspension.
Up front we find MacPherson type independent struts with coil springs and a stabilizer bar. While known for a relatively compact size and layout and efficient costs, these benefits come at the price of outright performance. Unlike a double-wishbone or multi-link style suspension, it does not allow vertical movement of the wheel without affecting the camber. The strut assembly is solely responsible for holding the lateral and linear forces applied to the top of the hub and must dampen at the same time.
Holding up the rear of the car is an independent double wishbone suspension with coil springs and a stabilizer bar. This double wishbone type is generally more desirable than a MacPherson setup as it provides a lower rate of angle and alignment change during the movement of the suspension resulting in a better response. The benefit is that the damper isn’t being side loaded at any point, so all it has to do is deal with vertical forces. All of the lateral load at the hub is relayed to the upper and lower control arms. On the other hand, when compared with a MacPherson setup, it is a more complex system that can take more time to service as well as weighing more due to additional components.
Check back to our building block article as we went into a few of the strengths and weaknesses of these types of suspension setups.
As you may recall, the overall build objective is to develop a high-performance street application with a focus on progressive technology. We want to take home trophies at the show on Saturday then tear up the track on Sunday. In regards to the progressive technology, we opted to go the air suspension route to truly test the progress of the technology. It’s slowly creeping its way into performance applications and we want to find out first hand what the buzz is all about.
For our BRZ, we’ve teamed up with the experts at Air Lift Performance and got our hands on a brand new Digital Combo Kit. This kit is filled with high-end features like 30-level damping adjustable struts, threaded body monotube struts, adjustable front camber plates, black chromed steel strut bodies, black powder-coated lower mounts and sharp bright red anodized aluminum end caps.
The drop this kit is capable of is quite impressive; front is 4.25” and the rear is 4.8”.
Traditional double bellows progressive-rate springs (the air bags) control height up front. . .
. . . and progressive rate sleeve springs (again, the air bags) manage the rear. One advantage to using air in the bags is that you can alter spring rates based on air pressure, something you cannot do with metal springs (without pulling them off and swapping for other springs).
Controlling the pressure and height is Air Lift’s V2 Digital readout which provides individual corner pressures, pump and pressure diagnostics and is individually adjustable and tuneable. It comes with 8 different presets to tailor your ride-height needs.
The first thing that hit us when opening the box was the overall quality of the kit. The aluminum and treated-steel components throughout really stood out as all of the components were crisp and clean.
Air Lift markets this kit as a "direct bolt on” and it appears to be true. This is one of the core competencies that Air Lift prides itself on, delivering direct bolt-in kits that require little beyond standard hand tools and little to no body modifications.
So, what’s actually in the box?
•Pair of air-over struts with camber plates
•Pair of air-over shocks with 30-level damping adjustment and threaded shock bodies
•Braided stainless steel leader hoses
•1/4 " & 3/8” PTC fittings
•¼” air line
•Advanced air lift manifold
•Viair 380 compressor
•Aluminum air tank
•All required mounting hardware
•Easy to use instructions
The kit also includes shorter and adjustable front swaybar endlinks. Why do you want these? As the ride-height gets lower, the new endlinks are to accommodate the large range of travel of the new system while the stock ones will bind at certain points.
Upon initial inspection, we may have find one downside to the kit: the front bags have a larger diameter than the stock coil-spring setup. This could potentially limit the front wheel width size and is something you should keep in the back of your mind if you’re going with a non-stock wheel size. Note that from the images shown here you can see how the lower perch height is a touch higher than OEM. If you're looking to go with larger and deeper wheels over OEM, then you definitely want to this. We'll be keeping a keen eye on this when we install the kit and spec the wheel and tire size.
With traditional performance coilovers we can reduce linear spring diameter to run wider wheels.
In this case, the bag diameter is 1/2 " larger than stock, 2.5” larger than the comparable coilover. Our team will have their work cutout for them when they are calculating the best offset to use with these bags and the widebody kit we’re going to install, but note that it’s simply an obstacle we wanted to qualify, certainly not a deal breaker.
As weight is a key performance parameter that we are keeping an eye on, we will weigh all components prior to installation to provide an accurate assessment of weight difference when compared with the stock suspension. Since it is a different set of hardware we aren’t quite sure what to expect.
Regarding strut housing there are some key differences depending on their intended use. For race applications you can expect to find aluminum housing, internals and packaging bits that allows for modular, repeatable and customized use. Problem with this type of setup is the ability to weather the elements. Street setups will generally have treated steel and be sealed so they can hold up to the elements that most race applications aren’t exposed to. For the Air Lift kit we find a blend of the two with a blend of aluminum and steel components with the remaining components comparable to premium street kit. We’ll let the pictures tell the story about construction quality.
So why did we chose this kit over the go-to coilovers? It’s the first air kit to include design around performance instead of just going as low as possible "drop it like it’s hot”. Air Lift designed the kit in harmony with the dampers for ultimate suspension control. Speaking of the dampers, they are 30-way adjustable for rebound and compression, which should be more than enough for our intended application. The spring rate is digitally adjustable with the amount of air and that same air also allows for micro ride-height adjustment.
Adjustable camber plates in front are a welcome sight since the stock car doesn’t have enough front camber, which becomes evident as soon as you increase grip. The kit comes with adjustable front top hats & fixed rears. Why fixed rears? Because the suspension is multilink and camber adjustment is at the control arm, requiring upgraded control arms.
For us, tuning will be a series of trial and error as this setup is slightly different (and very much so intriguing) than anything we have played with to date. For coilovers, you can adjust the spring rate without affecting ride height, but you have to completely disassemble the suspension to change the physical springs. With this kit, changes in effective spring rate are done electronically with the touch of a button. However, adjusting the pressure/spring rate also adjusts the ride height of the vehicle, so that makes it slightly more difficult to properly tune. What’s nice though is that we can have a track setting and a street setting (heck, even a show setting!), something you can’t get with standard coilovers without some sweat equity.
In the end, the kit’s struts and shocks are geared towards street performance and not extreme-load applications (in terms of stiction and damping). Based on what we’ve seen so far, though, we’re quite confident they’ll be up to the task of what we plan to put the BRZ through!
We’re VERY excited to see what this kit can do and can’t wait to get it on the car. Our expectation is the Air Lift system will be comparable to a high-performance street coilover set but we’ll just have to wait and see. SCR Performance will be dialing in the kit at the track to obtain a happy medium between extreme street performance and comfort. Stay tuned as we report back on what they find and as our build progresses. See you next week.
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