The 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 Toyota Corolla WRC
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.