After two installments of Project Saabaru, I started getting serious with the nuts and bolts on the 9-2X. Like the subtitle says, we changed the wheels and suspension setup to better reflect what this touring wagon should do. These alterations alone have significantly altered the 9-2X's character enough for me to enjoy driving it everywhere almost all the time.
Out of the box, the Saab came with great handling potential. But the ride height and civil damping of the factory setup took a slight edge off the car, both cosmetically and dynamically. The stock settings are pretty good for the average driver and the handling feel is right up Saab's alley. However, Project 9-2X will be driven a lot harder on both the street and the track--it's what we're paid to do.
The plan followed the usual route of replacing O.E. suspension components with aftermarket parts. Fortunately, there exists a cornucopia of parts for the Subaru WRX that directly bolt onto the 9-2X. Even though most parts on the market are for pre-2004 WRX models, these parts bolt directly on without a fuss. If a discrepancy occurred, the 9-2X could use parts for a 2004 WRX wagon as opposed to earlier model years. I selected parts from various manufacturers that best reflected the technology and quality I would expect to see in a tuned Saab. The difference between ec's build-up and others is the added effort put into the analysis and tuning of the system.
Wheels and Tires
The idea of using Work Wheels first occurred before Project 9-2X was even conceived. It was the factory wheels on our long-term Saab 9-3 Aero that reminded me of the dual five-spoke wheel design of Work Meister S2R wheels. The stock 9-2X wheels are similar , with slightly rounder edges. Naturally, Work wheels were the best choice for maintaining the Saab's style while adding some aftermarket flare.
Unfortunately, the Work Meister S2R wheels couldn't be built in the Saab offset. At the suggestion of AKH Trading and Work's engineers in Japan, I opted for a similar three-piece design, Work VS-SS wheels finished in Burning Black, which also have the same deep polished lip as the S2R, but with the added parts of a three-piece wheel. I chose an 8x18-in. wheel with a +48 offset on all four corners, since 8 in. is the maximum width that can be reasonably fit under the 9-2X's fenders. Just one size up from the factory 7x17-in. cast aluminum wheels, they offered a dramatic change in overall appearance. At 26 lb apiece, the VS-SSs were a good fit for the touring feel I wanted.
I picked Kumho's MX tire, a long-time favorite, for the needed grip and wear characteristics I was after, and had Shoreline Motoring perform the mounting and balancing. The 225/40/ZR18 tires completely changed the Saab's grip threshold--the factory tires were its limiting factors. With the MX tires, my lack of courage is the only thing keeping me from reaching lateral-acceleration nirvana. Outside of all-out track driving, it's been hard to get the tires to squeal even under the intense street cornering I do all-day long. The added stiffness of the sidewalls did take a little getting used to because of the added noise and every little road irregularity that gets picked up.
Anti-roll bars and lower control arms
Any significant alteration to the Saab's suspension had to start with changing the chassis' amount of roll and pitch. Much could be accomplished by simply increasing the suspension damping and reducing ride height. I've driven many WRXs and the stiffer stock suspension provides more cornering predictability. Saab sacrificed some of this for ride comfort and added on-center feel, which makes the 9-2X a better touring car, however, I prefer more cornering excitement.
Obviously, one way to reduce roll is by increasing the roll rate with stiffer anti-roll bars. Having installed and driven many aftermarket anti-roll bar kits, the street sway bar set by H-Sport I chose was on the higher end of the quality spectrum. H-Sport, Hotchkis Tuning's European division, provided the entire selection of its street performance parts for the Saab. The sway-bar kit uses 25.4mm hollow bars, front and rear, which increased the roll stiffness by 88% in front. The rear bar has three selectable positions, increasing roll resistance from 50- to 160% over stock. I chose the intermediate setting of roughly 90%. Reinforced rear sway-bar mounts are also included in the kit. Hotchkis also provided billet aluminum rear sway-bar end links. Though front links were also available, I opted to not use them because they have spherical metal joints instead of rubber bushings.
The increased roll rate alone took much of the understeer out of street driving. This added a lot of cornering confidence, especially since the Saab uses such a quick steering ratio. Now a quick snap of the wheel rotates the car instead of rolling and pushing it. I quickly realized this setup was a little too much on the stock tires. With the Kumho tires, however, street driving turned into a matter of precision asphalt carving.
In anticipation of the larger wheels, lowered suspension geometry and potential track use, I also added H-Sport adjustable rear camber links. These would allow me to get up to negative 3.5 degrees of negative camber in the rear for added grip or wheel clearance.
Adjustable Coilover suspension
As with the Work wheels, I had already picked out TEIN for the Saab's suspension well before the car was delivered. The main attraction was the TEIN Electronic Damping Force Controller (EDFC), which is an electronics package that can be installed onto the company's Type FLEX or Super Street coilover suspension systems. Each of these systems feature height and 16-way rebound damping adjustment and spherical metal bearings embedded in each of the mounting plates. The EDFC uses a stepper-motor mounted on top of each shock to control the shock valve position. The cabin-mounted EDFC controller allows the driver to adjust front and rear damping force independently while driving. Depending on the shock, the EDFC can be programmed to have 16 or 32 steps of damping force adjustment. Three settings can also be held in memory for one-touch adjustment.
TEIN also re-valved the Super Street damper system to meet my touring goals. This service is offered to all TEIN's customers. One of my primary concern was avoiding the ride harshness of many aftermarket coilover suspension systems. The rear spring rates were softened by roughly 20% to add some ride comfort and each shock was re-valved to match the spring rate and provide as civil a ride as possible.
To see the adjustment range of the EDFC system, I measured the damping force curve on TEIN's shock dyno for every four steps on a 16-step scale. This was compared to the stock shock curve profiles and to see where they sat relative to each other. The results fit within generally accepted conventions where compression damping forces (bottom) are typically 30- to 50% of rebound damping forces (top). Though compression curves have very similar profiles and taper off at similar piston speeds, the TEIN rebound curves offer a wider range of profiles and taper off at higher piston speeds.
Part of the drawback of using a station wagon for a performance platform is the added flex of an open-cabin body. Without additional chassis reinforcement, the aftermarket suspension had a way of twisting the body when the car ran out of suspension travel. I found GT Spec of Flushing, N.Y., a company specializing in quality chassis reinforcement parts for WRX, Mitsubishi Evolution and some European platforms. I ordered a basic aluminum front strut-tower brace, titanium rear strut-tower brace and four-point aluminum front sub-frame reinforcement brace. All of these parts are direct bolt-on parts from the WRX, except the titanium strut tower brace in the rear. The steel upright brackets had to be re-fabricated by our fabricator at Mavrik Motorsports to gain enough vertical clearance over the EDFC motors on top of each shock.
GT Spec also offered several other chassis braces, but these were left off my shopping list in order to minimize alterations to the passenger cabin. As this article is printed, GT Spec will also have a 12-point front and rear sub-frame brace available, along with an anti-lift bushing kit.
Some nagging problems I found with the new suspension and tires is the excessive amount of road noise transmitted into the cabin and limited wheel travel in the rear. Every passenger in the car has complained about this. The TEIN suspension doesn't use rubber shock mounts to increase road feel and steering response, causing most of the road noise to be conducted through the shocks and into the unibody. It doesn't help that the interior covers for the rear shock towers had to be left off in order to clear the EDFC motors and strut tower brace.
The stiff sidewall and symmetrical design of the Kumho tires also add to the NVH dilemma. The MX was never quite a true touring tire, but there are times when the droning of the tires starts bothering even me, causing me to lose the desire for driving the Saab. The noise clearly comes from the suspension and tire combination because when the car travels over newly paved asphalt, the 9-2X becomes quite silent. For now, these compromises are something I'm willing to deal with in exchange for the improved handling.
What I did change right off was the ride height. The Saab now rides 8mm higher (the photos were taken prior to this adjustment). The added travel significantly improved the ride quality and minimized the rear tires rubbing on the fender. I will eventually have to get them rolled. For now, the added travel means less three wheeling off of driveways.
I headed out to our local testing grounds to get vehicle handling numbers to compare to the stock. Though not a huge improvement in terms of skidpad or slalom speeds, the overall feel of the vehicle improved significantly. Much of the slop was taken out, giving the 9-2X an almost sports-car-like feel. Better numbers could have been reached with more aggressive camber settings, but I didn't want to compromise tire wear.
The suspension was fine tuned with the EDFC during the aforementioned tests. Initially, the suspension was set with equal levels of damping in front and rear, but this caused too much understeer and minimal yaw control with throttle modulation. The trick was to increase the rear damping 25% over the front to get a more neutral feel on both the skidpad and slalom. For all-out performance, I set the EDFC at 1 in the rear and 4 in the front (0 being the stiffest out of 16.) Most of the time I leave the car at 9 and 4, front and rear, respectively. For long-distance cruises, I program both front and rear to 16. To see what the Saab would do at the extreme, I also tried setting the front to full soft and rear to full stiff. The numbers were not any better than the full-performance setting, but the steering feel was extremely sloppy.
The final test was out at the Streets of Willow track. All of the deficiencies I found annoying on the street were quickly forgotten after a couple hot laps. The 9-2X was just phenomenal in its driveability, predictability and versatility--for all driving styles. It quickly became the favorite car; beginners and pros alike tossed it through the tight technical course. The combination of sticky street tires and streetable spring rates really brought out the true capabilities of Saab's entry-level platform. Validation came when a test driver from another high-quality suspension company commented on how well the car handled.
Now that the Saab turns, I'll set my sights on adding power with basic bolt-on tidbits and tuning.
|Table 1 Performance numbers |
| ||Slalom (mph)||200-ft skidpad (g)|
At a Glance
Estimated time: 11 hr @ $50/hr = $550
H-Sport sway bar kit: $371.21
H-Sport rear sway-bar end links: $135
H-Sport adjustable lower arms: $493.50
GT Spec aluminum front strut tower brace: $161.00
GT Spec titanium rear strut tower brace: $749
GT Spec front subframe ladder brace: $161
Work VS-SS wheels: $2840.00
Kumho MX tires: $432
TEIN Super Street Damper: $1,510
TEIN 4 kg/mm rear springs: $50 each
TEIN custom valving: $100 each
TEIN EDFC: $380
These Work VS-SS wheels measure 8x18.
These Kumho MX tires measure 225/40/ZR18 and completely changed the Saab's grip threshold.
TEIN Super Street damper kit with metal top mounting plates.
Modified rear top brace uprights and EDFC stepper motor