A Tech Look Under the Scion FR-S!

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For an easy brake upgrade, the Brembos from a Subaru STI bolt right on.  Which leads to the one thing we absolutely hate about the car.  Why oh why does it have a 5x100mm bolt pattern instead of the common 5x114mm?  This greatly limits the wheel choices for this car.  For front calipers you can use 2004-2012 STI parts while using the rotors from a 2004, the one year the STI used this bolt pattern.

At first glance the steering geometry seems to be set on toe in under compression which is great for braking stability but not so good for turn in response. Most race cars are designed to have a bit of toe out under compression for this reason.  A closer looks shows some clever tricks with the front lower control arm bushing.  The bushing is designed to comply inward under side load against the incompressible tie rod.  This makes the tires toe in under braking but toe out under cornering to improve turn in and reduce initial understeer, a best of both worlds scenario, pretty clever Toyota or Subaru, whoever thought of that.  Of course the aftermarket will make bearing kits and solid urethane bushings.  In this case it will be necessary to run a little static toe out.  

For the rear brakes, the 2008 + STI Brembo brake caliper will work perfectly using a rotor drilled for the 5×100 bolt pattern.

The brakes on the car are perhaps the easiest things to upgrade.  The Brembo calipers for a 2004-2012 STI will bolt right in the front.  For front rotors use the STI parts from a 2004 with the 5x100mm bolt pattern.  For rear brakes use the 2008+ STI parts and drill the rotors for a 5×100 bolt pattern. The bolt pattern is the one thing we really hate about the car.  5X100mm is an unusual pattern instead of the very common 5×114.3mm.  This greatly limits the number of aftermarket wheels available for the car.  If someone at Scion/Toyota/Subaru is reading this, please change this before production, pretty please!  A whole industry and all the fans and buyers of the car will thank you!  Subaru changed so you can too!

The rear suspension is very similar to the GE Subaru Impreza, being a somewhat unremarkable multilink.  The suspension has toe in under roll, a moderate amount of camber gain under roll and a bit of anti squat in the geometry.  All of this is pretty good to have in a RWD car.  The forward tilting lower link and the downward tilting upper link define antisquat with the forward instant center just forward of the cars center and above the center of gravity. The amount of antisquat is fine for an NA 2 liter engine but if the power is bumped significantly, the anti might need to be reduced to get the best off corner behavior.  The steel subframe can easily be modified for pivot relocation.  The suspension is pretty low profile which means more interior space.

The rear suspension looks like it was lifted right out of a late model GE Impreza .  It is an unremarkable multi link which is designed to toe in under roll with moderate negative camber gain.  This gives a tendency to have more rear traction under hard cornering reducing strong oversteer, good for a production car. There is a moderate amount of antisquat in the suspension geometry, is fine for the 200 hp production car allowing a soft nice riding spring rate without excessive squat under acceleration but when someone drops in a 500 hp EJ25 which you know is coming, the anti may need to be reduced and stiffer springs run to give the car more traction off of the corners and a more linear transfer to oversteer with the throttle.