Tech analysis: Toyota TF106

Even with a short history in Formula One, Toyota head into 2006 with high expectations from both within the team and the media. The team had their best season to date in 2005 - with a fighting fourth place in the Constructors' Championship, only losing third place to Ferrari as a result of not racing at Indianapolis. Yet, this expectation is fuelled not so much by a good 2005, but by the huge financial and technical resources the team have to draw upon.

With the second year of major technical rule changes and under the leadership of Mike Gascoyne, the team have the opportunity to lever these advantages and catch up with the leading teams. To do this, Toyota have opted for an intensive strategy of an early release of the new chassis, following that up with aerodynamic updates and a "B" spec chassis mid season.

Design and development strategy

In order to have the TF106 ready for the new season, the design work started way back during last season. With the V8 engine development already well under way, the chassis design work was lead by the results of the car in the first part of the season and the rule changes.

With the TF105 car designed under the time pressure of the late aero regulation changes, it was not completely optimised for the new front wing and diffuser requirements. Furthermore, the planned switch to Bridgestone tyres in 2006 would have demand a change in static weight distribution and suspension geometry. Hence, the concept for the TF106 needed major changes to the new engine, suspension and aerodynamics.

As F1 cars are so integrated, every area changed affected the other areas of the car. First, the tyre change demanded less forward weight distribution than the Michelins prefer. Second, the engine was ten centimetres shorter and the team wanted to retain the wheelbase, and also the team sought more aerodynamic efficiency.

The layout of the car and the major components is always the first work of the design team, and in Toyota's case they took the option of lengthening the chassis to create the rearward weight distribution change, as well as altering the fuel tank.

Gascoyne explains: "The wheelbase was kept the same by lengthening the monocoque in the fuel cell area. This allows a larger fuel volume and keeps the fuel lower in the car." This also allows more space for the front wing and bargeboards to work, while retaining the same length for gearbox.

Getting the front wing working better was the key to the car's new aerodynamics, already with more space before the sidepods impinged on its flow. The next area to focus on was the area under the raised nose of the chassis and the position of the front wishbones in the airflow.

"The improved aero performance came from raising the lower suspension leg," Gascoyne told autosport.com. Hence, the "keel-less" approach was carried over from the TF105B. Moreover, a suspension redesign was already planned to match the kinematics data from Bridgestone.

At this stage, the car's basic design was fixed and then detail design and aero development could take place. It was the lack of changes to the monocoque that allowed Toyota to complete the other changes demanded by the V8 in much quicker time than a full monocoque design. In simplistic terms, the 106 monocoque is a lengthened version of the 105B with a new rear bulkhead to mate to the V8.

The resulting work to complete the engine and gearbox (again, little changed) allowed the team to have a near-definitive 2006 chassis ready for the start of January testing.

Thus, Toyota were able to test the full mechanical package on track while the aerodynamics are refined in the lead-up to the first race. Of course, this makes the whole process sound easy, but it's the huge resources Toyota have at their disposal that allows such a constant rate of development.

While the chassis is completing its test runs, the aerodynamicists back at the factory are working on the next aero step that will shed the car off its TF105B-inspired bodywork and apply new sidepods, wings and floor. This upgrade will be used for the first flyaway races, before other smaller steps will appear on a race-by-race basis.

Then, for the Monaco race, the team will have aTF106B, which aims to upgrade the chassis based on race experience of the Bridgestones in the first half year. This interim upgrade may be a by-product of the rush to get the chassis out so early, as some of the feedback from an interim car - and the extra design time this allows - was lost in the rush to get the 106 chassis ready so early.

General design

As the car's aerodynamics and front end are those of the TF105B, the car appears very similar externally; certainly around the front end the car is indistinguishable from the 105B. Only when stripped of its bodywork, the car shows its differences to the V10-engined model.

The front end of the chassis mounts both wishbones direct to the tub. This keel-less approach improves the car's aerodynamics both by the better flow off the front wing and by improved quality of flow to the floor, increasing downforce on both ends of the car.

The chassis still retains the keel under the nose, but this is no longer used to mount the wishbones. Gascoyne explains this has been retained because "the (old) keel has no negative aero effect. Retaining it allows a better packaging in the area of the driver's feet and pedals and allows us to carry these parts over from the TF105."

V8 engine

Despite being in F1 for only five years, Toyota have a strong reputation as a top engine maker. Even in the team's first years, the Toyota engine was touted as one of the most powerful and most reliable. All this came from a background with little high-level race engine experience. Their rally cars used production engines, while the Champ Car and endurance engines were not at the same level of technology as F1.

Even within F1, Toyota have been ahead of many teams in areas of engine design. The team's single ECU controls both chassis and engine parameters, and this allows for very clever control strategies, by using the engine to control the car's handling dynamics.

One of the systems Toyota have used has been a very long stroke variable inlet trumpet, and the whole of Toyota's inlet port design has been radically altered to suit these trumpets. This allows the team to accurately map the inlet system for the best power delivery.

Furthermore, the team and their parent company's development resources have allowed Toyota to investigate expensive solutions, such as thin wall magnesium castings for use on the engine.

However, the FIA's rules to limit engine development and hence costs have affected Toyota more than most. The ban on inlet trumpets, move to single injectors per cylinder, and materials limitations (including magnesium) mean that Toyota had a bigger step backwards than most teams when designing their V8.

They did, however, make use of their resources to have a mule engine running after the V8 rules were initially announced and soon had a purpose built V8 running just around the time the details of the rules were clarified. This forced Toyota to build yet another engine to the strict wording of the rules. This unit first ran in March 2005 but it was a while later before it complied with the 95kg minimum weight.

Development work has so far centred on the reliability of the unit at each targeted power output. To date, the initial power target (which Marmorini refused to divulge) has been met and more targets are planned between now and the first race. Vibration has also not been a major issue most would have expected.

Peak power is often the sole aim people seek for race engines, but Marmorini is just as interested in the spread and smooth delivery of the power. Additionally, he needs to take account of how the engine will be used by the driver.

It is clear the V8 will lack torque and power compared to the bigger V10, and this means the drivers can use the engine at full potential for longer. The telemetry is showing peak revs, and fully open throttles are used for more of the lap than before.

Marmorini explain this as "on/off" use of the engine and in saying so, he is not suggesting the power delivery is "all or nothing." Rather, the drivers do not need to modulate the throttle so much, as full throttle will not overcome the tyres' traction.

The driver is able to floor the pedal and not fear the same overwhelming power delivery of the 3.0 litre V10. This change in engine use was first detected when the team ran detuned V10 engines for the drivers and engineers to appreciate what the effects of the V8s would be like. This preliminary test directed the development of the V8 and how the chassis would need to react to the new engine.

Toyota's engine designers are working on a better spread of power, no longer supported by the variable trumpets. Likewise, the chassis designers now realise the cooling and fuel consumption is not going to be 20% less (to match the capacity decrease) as the engine will be used harder. A figure nearer to a 10% drop on fuel economy and cooling from the V10 is the expectation, forcing the chassis designers to accommodate much less reduced coolers and fuel tanks.

Engine installation

One of the new rules dictated for the new V8 was a minimum weight for the engine. At 95kg this is probably 5-10kg more than the V10 was, plus the engines are one fifth down on the weight pistons, crank and block, etc.

A little mentioned rule change is a limit on removable ballast to just 2kg, so the engine will simply be made super light, with blocks of lead added to make up the weight.

Between the engine and chassis departments, Toyota took the route to make use of the extra weight in the engine block, providing a stiffer installation and the reduced weight of related components.

The new engine features very stout block, with the front face enlarged to mount to the back of the monocoque in six broadly spaced locations, whereas usually only four fixings are used.

This makes the engine chassis interface stiffer and probably allows some weight to be taken out of the back of the monocoque. Equally, at the rear face of the engine, the stiffer block mounts both the gearbox and the rear suspension.

While Ferrari have already placed the rear upper wishbone mount between engine and gearbox, Toyota have now mounted both the rear upper and lower wishbones onto the rear of the engine. This allows weight to be taken out of the gearbox, as it no longer needs to feed the large loads from the front of the wishbones through its casting and into the engine.

When viewed from the rear, the lower wishbone mounts to a simple clevis, which mounted to the back of the cylinder hear, while the upper wishbone appears to mount on an extension of the cam cover.

Rear suspension

The first Toyota F1 chassis struggled with performance over bumps. Even with the use of the seven-post rig to test the suspension's compliance (the action of the dampers and springs on wheel travel), this problem persisted.

Gascoyne made progress with the TF105, and by testing through the year he highlighted more issues with the rear suspension.

For the TF106, the rear suspension needed to be mated to the improvements with the front suspension and the new tyres. A major redesign has gone on, with the neat installation eschewing the Sachs rotary dampers for new telescopic Penske units.

Its not clear if the change was due to inherent advantages in a telescopic over rotary designs, or whether Penske had a product that worked better for Toyota.

Either way, the change in damper format lead Toyota to redesign the torsion bar arrangement and the rocker that operates the dampers and roll bars.

The inclined torsion bars now operate rockers that push on forward mounted dampers and a T-shaped anti roll bar/third spring. This is a neat set-up and doesn't need the large blister on the engine cover to clear the third damper on the old car, which should also be an aerodynamic improvement.

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- The Autosport.com Team

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