Car Design News: Toyota TRD Aurion In Depth (AU)

UNIQUE PERFORMANCE BRAKE PACKAGE FOR TRD AURION

TRD Aurion has adopted a TRD-specific brake system for increased performance, better feel and a high degree of modulation. TRD engineers developed the system in Australia with supplier PBR. The TRD Aurion brake system includes new disc rotors front and rear, new aluminium calipers front and rear, and performance friction material. TRD Aurion has 325mm by 32mm ventilated front discs with twin-piston aluminium calipers. The Aurion Sportivo has 296mm by 28mm ventilated front discs and single-piston cast-iron calipers.

At the rear, TRD Aurion has 310mm by 18mm ventilated discs and single-piston aluminium calipers, replacing 286mm by 10mm solid discs and cast-iron calipers on the Sportivo. Ferodo HP 1000 performance pads are used front and rear on TRD Aurion.

TRD AURION HAS UNIQUE SUSPENSION PACKAGE

New TRD Aurion has a unique Australian-developed suspension package, designed to deliver a dynamic, rewarding and high-quality driving experience. It is based on the TRD suspension philosophy of matching spring and damper performance to provide increased control, agility and response while delivering a high-quality sports ride. The suspension calibration is based on ensuring all the suspension elements work towards the focus of control. TRD Aurion has increased spring rates front and rear, compared with donor Aurion Sportivo. The front spring rate has been increased by 11 per cent and the rear spring rate by 10.5 per cent. Ride height has been reduced on average by 12mm.

The dampers have TRD-specific damping force curves, with increased front rebound damping, and increased rear damper force in both bound and rebound. The new damper curves improve body control while also making improvements in ride quality and the feeling of quality and solidarity. The stabiliser bars are as per Sportivo: 25mm diameter front and 16mm diameter rear.

However, TRD Aurion also has the body control benefit of TRD-specific tuning for the internal rebound spring in the rear damper units. The revised tuning means the internal rebound spring has less free travel and a retuned rate to invoke earlier and more frequent engagement, which improves body control without compromising ride. The TRD Aurion rebound spring assists the damper units to better control vehicle roll, steering response and overall dynamic balance during handling manoeuvres. The final calibration balances ride quality with damping force specification.

In addition to its new suspension calibration, TRD Aurion has new wheel alignment specifications front and rear. It has increased negative camber for improved yaw response and agility. Front toe-in has been increased for improved steering feel and response. The rear suspension has neutral rear toe, to improve initial turn-in, nimbleness and responsiveness.

The high-grade TRD Aurion 3500SL has a stiffer rear bumper reinforcement than 3500S to increase steering rigidity on centre, reduce impact shake and reduce audible impact frequency. This results in a feeling of higher quality, with a European taut body feel and a tighter dynamic experience. The reinforcement is an extruded aluminium member that replaces the standard pressed steel bumper cross-member.

TRD Aurion's wheel and brake designs also contribute to the vehicle's dynamic performance. The 19x8-inch aluminium alloy wheels are designed to improve brake ventilation and vehicle dynamics, while preserving impact resilience. The tyres are 245/35ZR19 Dunlop SP Sport Maxx for high stiffness and optimum response and control.

The SP Sport Maxx is Dunlop's number one performance tyre. These ultra-high-performance, low-profile tyres were chosen for maximum dry grip and wet-weather performance. Advanced compounds, multi-radius tread design, construction and tread-pattern design ensure maximum wet and dry handling, sharp dynamic response and low tyre noise.

TRD Aurion's new brake package with aluminium calipers provides increased braking power without any penalty in unsprung weight (and no increase on the force needed to control the wheel when it strikes a bump).

TRD AURION SUSPENSION AND BRAKES LOCALLY DEVELOPED

The suspension and brake package for new TRD Aurion was developed in Australia. The suspension development program followed five steps, using a combination of race circuit and public road evaluation and testing. The two steps in the suspension tuning were spring tuning (in two stages) and damper tuning (in three stages). The next three steps were tyre testing and selection, performance measurements, and development testing and certification.

Testing venues included Winton and Broadford race circuits in central Victoria, as well as a variety of country and suburban roads. The final suspension calibration includes a unique TRD Aurion front and rear wheel alignment setting, and the adoption of a stiffer rear bumper reinforcement on the 3500SL model.

TRD Aurion brake development was conducted with supplier PBR. PBR's predictive analysis and simulation tools provided the baseline for the brake package development. The sophisticated PBR development software provides information on brake temperatures after a single stop from 250km/h and 20 stops from 160km/h, based on various brake hardware combinations.

The variables are piston configuration, pad friction coefficient and rotor diameter - for both the front and rear brakes. TRD engineers therefore had a starting point for on-track and on-road brake testing. The brake package selected has 325mm front ventilated discs with twin 40.5mm piston aluminium calipers, and 310mm ventilated rear discs with single 40.5mm piston aluminium calipers.