Reseña histórica:
Toyota was the first Japanese company that tried, and later succeeded, to beat European manufacturers in the World Rally Championship. Their Celica has gone through many mutations since it first took part in world class rallying back in 1988 in the Tour de Corse rally. As usual Japanese manufacturers come up with a new version of their cars every two years. This didn't seem to cause too many problems to Toyota Team Europe, the team that prepares the racing cars. There was always a period of adapting a new model to rally racing but this usually took less than three months.
The commercial versions of the Celica went through a number of updates starting with the original ST165 (1987-1989) going to the ST185 (the bio-design car, 1990-1992) and lastly the ST205 (1993-1999). The competition cars followed this evolution closely.
The first 4WD version (ST165) suffered mainly from heat problems not having enough air circulating in the engine compartment. This problem was partially fixed in the ST185 with the addition of an engine bonnet vent. The ST205 was the most accomplished version, aerodynamically speaking.
The Celica has been a hard to beat contender ever since its introduction in the WRC when it raced against the Lancia Integrale in 1989-90. Toyota won 38 WRC rallies and 2 WRC Championships ('93 and '94) with it.
The Toyota team was promised to success up to the Catalunya rally in 1995 when an FIA commissioner discovered a weird device in Didier Auriol's Celica ST205.
To limit the horsepower in rally cars the FIA has regulated the use of a turbo restrictor. This is device, resembling a tube, with a regulations specified dimensions fits in the turbocharger's air intake to limit the air flow and consequently the engine's output.
Toyota engineers had mounted the restrictor in a way that it would slightly move from its original position, allowing more air into the turbocharger, when the car was running. This of course was prohibited and as a consequence Toyota was excluded from the World Rally Championship. Too bad for their drivers, Juha Kankkunen, Didier Auriol and Armin Schwarz at the time, who declared they knew nothing whatsoever about the presence of such a device in their cars. No one ever found out whether the device came from Toyota Japan or from Toyota Team Europe. Either way each party must have known about its presence.
That was a really sad moment for the rally racing world. Especially so because Toyota was one of the most (if not the most) innovating teams around. They, first, introduced hydro-electronic differentials, they introduced the A.L.S. (a.k.a. bang-bang) engine management system as well as the "joystick" gear change interface (in the Corolla WRC) among many other innovations.
Anyway back to the car now, the Celica GTFour was based on the production Celica versions and looked almost exactly like one. The latest street version of the car contained some very fine engineering. The 2 liter 4 in-line engine was derived from the atmospheric (non turbocharged) version and delivered anywhere from 220 Bhp in its first versions to 242 Bhp in the latest street GTFour. Turbo lag time was kept within reason due to the use of a small, in-house, CT-20 turbocharger. Many technical innovations where present in this engine and car. You may note among others:
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An electronically controlled turbocharger (Toyota Computer Controlled System) which also handled injection and ignition
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Specially shaped intake and outlet tubes
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A very cleverly designed two-way catalytic converter which reduced back pressure on the turbo
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A water to air intercooler whose water was cooled in an extra water cooler
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Increased water and oil flows compared to older versions of the engine
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The Fresh Air Intake System, a device producing almost the same effects as an A.L.S. (this was unfortunately disconnected in street cars due to excessive exhaust tube stress and noise)
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4 piston aluminum brake calipers in the front wheels and 315!mm vented brake discs
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Many parts of the body where in aluminum including the engine bonnet, parts of the chassis, etc.
The specification of the street version ST205 Celica can be found here. As you might have already guessed this was some car. Toyota delivered more in the Celica GTFour than one could hope for. The Torsen (which stands for Torque Sensing) rear differential was a very good surprise too. Previously used in the Lancia Integrale and the Audi Quattro this device generates extra costs to the overall price of the car. No wonder the Celica GTFour was the most expensive street versions of the homologation specials. The one problem the street Celica version was suffering from was its weight. A laden weight of around 1450Kg is way too high for a "sports" car and generates important inertia-induced parasitic movements. This fact influenced badly the car's handling abilities.
Even more technology was packed in the competition version of the Celica GTFour. You see Toyota really wanted to win the WRC title. Rally used to be a very important part in Toyota's marketing budget at the time. The team hired two of the most talented rally drivers ever: Juha Kankkunen and Carlos Sainz and invested huge amounts of energy and money to beat the Lancia Integrale, at first, then the Ford Escort RS Cosworth and finally the Subaru Impreza. They managed to succeed.
he latest Group A version of the Celica GTFour was a very balanced car to drive. The factory cars used XTrac gear boxes and where equipped with a system called Hydraulic Torque Sensor. This system continuously varied the part of engine torque sent to the front or rear wheels depending on whether the car was accelerating or braking. As usual in rally cars all chassis where reinforced and many more welding points applied than in normal, street, cars.
The biggest disadvantages of the Celica GT4 when compared to other successful Group A rally cars, were its dimensions and the driver's limited visibility. Most Celica drivers used to complain saying they were feeling as if they were sitting in a Porsche when driving the car. Ove Anderson (an ex-rally driver himself), Toyota Team Europe manager, spent many years trying to convince Toyota Japan that the Corolla class of vehicles was much more suited to rallying. With the new WRC car regulations in effect since January 97 he finally succeeded to develop a WRC version of the Corolla.
The Corolla WRC car (photos here and specs here) was first introduced in the Monte Carlo WRC event in 1998. Toyota officials stated that during its development stages the car was already 0.7 sec/Km faster than the Celica on tarmac! The Corolla WRC has proved a very competitive car and ultimately made it to become World Champion. The car was driven by Didier Auriol and Carlos Sainz in the 1998 and 1999 WRC. The Corolla is everything David Richards (Subaru/Prodrive manager) wanted WRC cars to be but was unable to deliver in the first incarnation of the Impreza WRC. The car vaguely looks like the street Corolla version but the resemblance stops there. It was a 4WD turbocharged monster (whereas the commercial Corollas are 2WD and have no turbo engines) which was compact and powerful enough to defeat any competitor. To produce a Corolla WRC chassis from a street version chassis, 400 work hours were necessary. Imagine the work put into it. The WRC Corolla engine was a derivative of the Group A Celica engine with all the little (and big) tweaks the WRC regulation allows. Hence the car was very well balanced (54.4% of its weight on the front wheels as compared to the Celica's 61% !!) and tame. It's 11cm shorter than a Ford Escort RS Cosworth and 24 cm shorter than a WRC Subaru Impreza. The Corolla WRC engine (i.d. ST 205) developed 300 Bhp (that's what Toyota said to comply with the 300Bhp limit set by the FIA, please read 350+) and a huge amount of torque (at least 500Nm). The engine was receded by 20mm in the Corolla body and inclined towards the back as WRC class cars regulations allow. The car used a custom Toyota turbocharger (model CT20) which rendered the engine usable from 3500 rpm up to 7250 rpm (the Celica's engine was only usable up to 6000 rpm).
The biggest innovation the Corolla WRC brought to rally cars was its gear box (made by XTrac). This box is a sequential one (i.e. non H-pattern based) but was coupled with a "normal" H-pattern command in case the sequential command fails (which is often the case in sequential boxes). The sequential shift was assured by a joystick fitted right next to the steering wheel. The joystick control was linked to the gear box through electronic circuitry, there was no direct mechanical connection. Once again Toyota innovated. Take a look at the WRC Corolla's interior here. Otherwise the car's transmission was based on hydro-electronic front and center differentials that were soon joined by a rear differential of the same kind. Beginning with the 1999 season the team reverted to a "classic" sequential gearbox operated by levers.
Toyota employed, in 1998, Didier Auriol and Carlos Sainz as its main team drivers while drivers such as Grönholm in Finland, Fujimoto in Indonesia, Aghini at the San Remo, Loix at Portugal and Schwartz in the RAC were used occasionally.
Another important feature implemented in the Corolla WRC car was its huge suspension travel. Suspension travel is what makes a rally car really efficient on the road. The more of it you have the better. In the Corolla Toyota Team Europe managed to implement a whole 20cm ! of suspension travel. You'd think its an off-road car... By the way, the very limited suspension travel was the major problem that used to plague the Lancia Integrale and continues to handicap the current Mitsubishi Lancer Evolution VI especially at the rear wheels for the latter car. Lancia never managed to provide enough travel in the Integrale's suspension not even in the evoluzione version. Toyota where able to provide that much of suspension travel because the WRC regulations allow major body and suspension modifications in a WRC car that are not possible in GroupA cars such as the Lancia or the Mitsubishi. All the complexity fitted in the new WRC Corolla was subject to problems in racing conditions. Toyota used as many duplicate/alternative/redundant parts as possible in the race car to avoid unpleasant surprises.
The Corolla's anti-roll cage is made up of 48 meters of steel tube. It provides the car's body with additional rigidity and it is quoted to be 30% more rigid than an equivalent Celica body.
A total of 57 Toyota Corolla WRC cars left the TTE workshops between 1997 and 1999. Among these 33 were used by the works team while the other 24 were sold to private teams.
The Corolla WRC's evolution, throughout its existence, can be summarized as follows:
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1997: First prototype (chassis number 601) used for tests and development. A total of 13 works cars where manufactured during that year 5 of which were used for testing and development
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1998: 21 works cars manufactured 7 of which were used for testing and development. Main differences compared to the previous series comprise: Braking system, new fireproof engine bay, new exhaust manifold, engine electrics and turbo
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1999: 15 works cars manufactured 2 of which were used for testing and development. Main evolutions include: 3 active differentials, new engine block and head (Lexus derived), new exhaust manifold, new inlet manifold with 4 butterflies, use of more lightweight materials to bring weight down including a aluminum bonnet. The last Corolla WRC ever manufactured was carrying chassis number 639 (chassis numbering was not linear as the highest number is 677)
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2000: No new cars were manufactured. Some evolutions were applied to already existing ones including a modified suspension layout and a joystick gearlever.
There are still private cars competing in WRC events even though Toyota officially retired from the WRC. These are managed by private teams and are available for renting by private drivers.
The Celica was the last of this breed of rally cars to go out of production. 2wd versions of the Celica will remain in the manufacturer's catalogue but the 4wd turbocharged car is doomed (you know, marketing...). Thus the Celica GTFour joins the Lancia Integrale, Ford Escort RS Cosworth and Audi Quattro (amongst others) in the cemetery of gone kings of the road.
Sadly, in mid 1999, Toyota announced that their competition department, the TTE, would retire from the World Rally Championship to concentrate on F1 racing and CART. The team managed to conquer the World Manufacturer's title for that same year with the Corolla WRC although the car was in desperate need of development. A beautiful ending for the TTE rallying history. Some private teams, like the Italian Grifone, were to still develop the Corolla and participate to some rallies but TTE's announcement effectively meant that Toyota was to stop its rally campaign. Both team's drivers, Didier Auriol who ended up with Seat and Carlos Sainz who signed with Ford, an acquaintance of old had to look for driver seats elsewhere.
