Project Scion TC Part 4: Suspension and Brakes


Ekei RPF01
Enkei RPF1 wheels are strong and light.  Look at the car in the MotoIQ Enkei ad, look familiar?

After installing the Progress Suspension, Energy bushings, camber plates and bolts, Darrin Nishimura at West End Alignment aligned and corner balanced our suspension.  Our suspension had a crude eyeball alignment before and the editor who performed this task must have been named Eileen, because the wheels sure leaned inward like a knock kneed librarian.  The rear camber was reduced from over 3 degrees negative to 2 degrees.  Our front tires were in the vicinity of zero degrees of camber.  Since we could not get enough negative camber, even with camber plates, Progress added a camber bolt to one of the two spindle bolts so we could dial in some negative camber. We set the front suspension at 4 degrees of negative camber while the front and rear toe settings were set to zero.  This is a substantial improvement and will contribute greatly to front grip while reducing understeer.

Carbotech XP11 pads
Carbotech XP10 pads are a lot more heat and fade resistant than typical high performance brake pads.  They are not really for the street though.  They will have a tough job stopping a pretty big and heavy car.

The rear ride height was found to be disproportionably lower than the front so it was raised to reduce the chances of it bottoming out under roll.   At this time, the corner weights were also set for a 50% crossweight.  Corner weighting is weighing the car through each individual wheel and adjusting the spring perches until the diagonal cross weight percentage is equal or 50%.  This assures that the car will have equal understeer/oversteer balance in both right and left turns.

Goodridge braided steel brake lines improve pedal feel as they do not swell under pressure like the stock rubber lines do.  The firmness puts every bit of pedal force into the calipers instead of swelling brake lines.

Lightweight and strong Enkei RPF1 MAT rolled forged wheels were selected as the rim of choice for Project Scion TC. These lightweight wheels use Enkei’s proprietary MAT process, a spin forming operation that draws the cast wheels rim section over a mandrel while it is turning.  This strengthens the wheels highly stressed rim section through grain refinement caused by cold working the metal during forming.  The metallurgical changes to the rim seen in MAT are very similar to those of forging.  MAT helps a cast wheel get much of the lightness and strength associated with forged wheels at a lower cost, giving a good bang for the buck. 17×8 RPF1’s wrapped with sticky Nitto NT-01 race compound tires were selected to hold the car up.  As to not incur PT penalty points the tires were limited to a 235 size which is relatively narrow for a relatively heavy race car. The Nitto’s renowned temperature and wear resistance is essential for this tire size limited situation as a heavy car on a narrow tire must manage the tire temperature carefully so as not to overheat and damage them during a race.

braided steel line in place
 Braided steel brake line in place.

Braking is quite important for a road racing car but to keep from accumulating PT penalty points, exotic braking systems were ruled out.  Instead temperature and fade resistant Carbotech XP10 pads in the front and XP8 in the rear grip the stock rotors.  Fade resistant Motul RBF 600 brake fluid is routed through Goodridge braided steel brake lines eliminating mush at the pedal .

Stay Tuned, in the next edition of Project TC, we will attack the engine to gain some power without incurring too many PT penalty points.

Safety Equipment Standards 

Roll cage fabrication

Carbon fiber hood
Pole Position seats

Toyota Racing Development
Parts Support, Limited Slip Differential
The Progress Group
Coilover suspension, Adjustable racing antisway bars

Carbon fiber roof
DC Sports
Headers, exhaust

Cold Air Intake

Nitto Tire North America
NT01 Tires
Brake pads

Tire Rack

Dezod Motorsports
Engine development, Scion tC performance parts
America’s Tire
Tire mounting/balance support
Safety equipment

turn3 Creative

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