The Toyota Celica GT-Four is a high performance sports car and variation of the Celica Liftback, produced from 1986 to 1999, with a turbocharged 3S-GTE engine, and full-time AWD. It was created to compete in the World Rally Championship, whose regulations dictate that a manufacturer must build road-going versions of the vehicle in sufficient numbers. These vehicles are referred to as "homologation special vehicles".
The Celica GT-Four came in three generations; the ST165, based on the fourth generation Celica, and manufactured between October 1986 and August 1989; the "super round" shape ST185 produced from September 1989 to September 1993; and the ST205, built from February 1994 to June 1999.
The Celica GT-Four production cars were built at Toyota's Tahara plant in Aichi Prefecture, Japan, and the rally cars were prepared by Toyota Team Europe in Cologne, Germany.
The Celica GT-Four ST165 made its World Rally Championship (WRC) debut in the 1988 Tour de Corse, with its first WRC victory coming in the 1989 Rally Australia. The ST185's WRC debut was in the 1992 Rally Monte Carlo, and its first WRC win was in the 1992 Safari Rally, which was one of its four victories in that year. The ST185 was Toyota's most successful rally car for more than two decades until this position was taken by Toyota Yaris WRC, and now the GR Yaris Rally1. The Celica ST185 won the WRC Drivers' Championship in 1992, and the WRC Manufacturers' and Drivers' championships in 1993 and 1994. The ST205 came in late 1994, and became the official rally car in 1995 with one WRC victory before disqualification. It also won the 1996 European Rally Championship.
The significance of the Toyota Celica GT-Four in WRC history, previously dominated by European manufacturers, is that it was the first time a Japanese car manufacturer entered the WRC with an AWD turbocharged car, took trophies and won the titles. Since then other Japanese manufacturers have been successful in the WRC. Toyota preceded the Mitsubishi (Lancer Evolution and Galant VR-4) and the Subaru (Legacy and Impreza), but not the Mazda (Mazda 323GT-R & 323GT-X). Toyota later exited the WRC to concentrate their racing efforts in Formula One, but in 2017, 11 years after the Celica was discontinued, Toyota returned to WRC with the Toyota Yaris.
Toyota Team Europe (TTE) was also the first to introduce the anti-lag system (ALS) in their Group A ST205 Celica GT-Four rally cars, a technological breakthrough that was later adopted by other teams.
GT-Four Full-time 4WD / AWD System
The Celica GT-Four introduced Toyota's first performance drivetrain that powered all four wheels. Transverse layout AWD systems typically are front biased, only capable of up to 50% torque as it relies on the front axles to power the rear axles. However despite using a transverse layout for the engine and transmission, the GT-Four system cleverly used hollow splined shafts to provide power to the centre differential first to produce a true 50:50 system. The transmission's driven shaft is geared to the centre differential. Then from the centre differential, the left side gear is connected to the front differential through a short hollow shaft while the right side gear powers the rear through another hollow shaft connected to the transfer pinion. The most important piece is a driveshaft inside both hollow shafts to power the right front wheel completely isolated from the shaft powering the rear wheels.
The use of hollow shafts isolates the front power delivery and rear power delivery. They are both powered by the centre differential. This allows for a torque split capable of 100:0 to 0:100 rear bias. However to control power split, Toyota also included a viscous limited-slip coupling joining the left and right side gears of the centre differential to keep it steady at 50:50. In certain conditions such as no grip to the rear tires, one can visibly observe rear bias as only the rear tires will spin before the viscous coupling gives back some torque to the front. Early ST165's (86 and 87 models) used a vacuum-operated actuator to lock the centre differential. This would allow for full range of torque split from 100:0 to 0:100 without the centre locked, and it would be stuck at 50:50 with the centre locked and as such only recommended for off-road use.
The GT-Four system is closer to a 4WD system rather than an AWD system because it is powering 4 wheels equally at the same time and there is always a coupling keeping the fronts and rears locked. This is especially true of the early ST165, as the solid-locking centre differential cannot be used on pavement when turning without risking damaging the drivetrain.
All three generations of the Celica GT-Four used the same basic system. However, the ST185 RC and ST205 also have a rear Torsen limited-slip differential (LSD) as standard. For the regular ST185, the rear Torsen is standard or optional depending on the year and original market.
ST165 (1986–1989)
The Celica GT-Four concept started with a convertible prototype displayed at 1985 Tokyo Motor Show. It was the first car to be officially called Celica GT-Four with the theme "Open Air 4WD Sport". The convertible never went into production, but the concept went to the liftback model which began production in October 1986.
The ST165 GT-Four can be distinguished from the front-wheel-drive Celica by its front bumper, which has larger openings and round fog lights on each side, and the "GT-Four" decals on the doors. Inside, the original GT-Four has a differential lock switch near the hand brake for the pre-facelift model built from October 1986 to September 1987.
The Celica GT-Four was updated in October 1987. As with other front-drive Celicas, the ST165 received a new grille, tail lights, and alloys. The export version also has ground effects, noticeably the side spoilers. The center differential was changed from a manually lockable unit (either open or locked) to a viscous-coupling limited-slip type. The GT-Four was marketed in the US as the All-Trac Turbo and in Canada as the Turbo 4WD.
The ST165 was not sold in North America before 1988 except for seventy-seven special-edition cars sold to commemorate Toyota's IMSA GTO championship win. These Celicas are all white with white wheels and blue interiors and have "IMSA GTO Champion" printed in small letters on the side moulding, as well as white stripes on the grills. One car was sold at each of the 77 Toyota dealerships in California. They were sold in 1987 as 1988 models, and have viscous-coupling center differentials.
When the Celica GT-Four was launched in the United Kingdom in March 1988 it was the first car sold in the United Kingdom designed to run only on unleaded gasoline.
The ST165 was the only car to be sold with the first version of Toyota's 3S-GTE. It developed 182–190 hp (depending on the market and model year) and of torque.
ST185 (1989–1993)
The first 21 units of the Celica ST185 were built in December 1988 as prototypes for various tests. The production model was launched in Japan in September 1989, and delivery began a month later.
The 3S-GTE in the ST185 GT-Four features an air-to-air intercooler and CT26 twin entry turbo to eliminate exhaust gas interference. The Japanese market GT-Four has of power and of torque, a result of more aggressive ignition advance and ceramic turbine. The Full-time 4WD system in the GT-Four has viscous coupling center limited-slip differential and some models are equipped with a Torsen rear differential.
All export market GT-Four are wide-body Liftback models with flared fenders. The Japanese market GT-Four was also offered as narrow body for the pre-facelift model.
In August 1990, the wide body GT-Four A was added into the Japanese lineup. It shares the same wide-body shell as the export version models. Super Live Sound System with 10 speakers became standard on the GT-Four A. ABS, automatic air conditioner, leather seats, and sunroof were optional.
Japanese market ST185 Models Production Date Body Style Model Code Model Name Intercooler type Base Price (¥'000) Remarks October 1989 – August 1991 Normal-body Liftback E-ST185-BLMVZ GT-Four Air-To-Air 2,685 Optional: ABS, Auto A/C, Leather, 10-Speakers Super Live Sound System, Sunroof. October 1989 – August 1991 Normal-body Liftback E-ST185-BLMVZ(V) GT-Four V Air-To-Air 2,427 Economy model with wheel covers (no alloys), no fog lights, limited options. October 1989 – August 1991 Normal-body Liftback E-ST185-BLMVZ(R) GT-Four Rally Air-To-Air 2,385 Rally model with close ratio gearbox, steel wheels, no power window. August 1990 – September 1993 Wide-body Liftback E-ST185H-BLMVZ GT-Four A Air-To-Air 2,900 (Aug '90 launch); 2,975 (Aug '91 facelift) Similar to all export models, equivalent to All-Trac in the US. Facelift model is simply called GT-Four. August 1991 – September 1993 Wide-body Liftback E-ST185H-BLMVZ(R) GT-Four Rally Air-To-Air 2,691 Rally model with close ratio gearbox, steel wheels, no power window. The rarest ST185 model. August 1991 – February 1992 Wide-body Liftback E-ST185H-BLMQZ GT-Four RC Water-To-Air 3,171 For WRC Group A homologation. Export version is called Carlos Sainz Limited Edition in Europe and Singapore, or Group A Rallye in Australia.
There are three different types of gearbox for the ST185 GT-Four. The E150F with 4.285 final gear ratio was installed in the regular Japanese models and All-Trac. The European and Australian specs come with E151F with 3.933 ratio. The Japanese market only GT-Four Rally has E152F with close ratio on the 1st through 4th gear and 4.285 final ratio. All the RC/Carlos Sainz/Group A Rallye have E151F.
Anti-lock braking system (ABS), Leather interior, Sunroof, and System 10 Premium Sound System are optional on '90–'92 All-Trac Turbo, and standard on '93 model year All-Trac Turbo. With its sport-style interior, power-operated driver's seat, auto tilt-away steering wheel, SRS Airbag, and cruise control as standard equipment, the ST185 All-Trac Turbo was the most expensive Celica yet. With a 2.0 L turbocharged 3S-GTE producing and of torque, it was the most powerful Celica ever sold in the US. In Canada, the ST185 was simply marketed as the Turbo 4WD. It was similar to the US All-Trac, but has a different lighting system with the fog lamps as Daytime Running Lights (DRL) for the compliance with local regulations.
The European versions have standard ABS and small bonnet spoiler near the windscreen. Headlight washers and heated door mirrors are also offered. Sunroof came standard in the UK models, or optional for cars in the Continent. However, System 10 Premium Sound System and Leather interior were only available as options in selected European countries, and were not offered in the UK.
The Australian spec was less luxurious than for other market. Cruise control, leather interior, sunroof, and System 10 Premium Sound System were not offered. Early models didn't have ABS and fog lights which became standard a few months after introduction.
Like other 5th generation Celicas, the GT-Four received minor changes in August 1991 for the 1992 model year. This facelift included the new Toyota ellipse emblems on the hood and trunk, restyled tail lights with smoked red frame, and shorter gear shift. The Japanese GT-Four also got round-shape front fog lights with yellow bulbs. Option packages for the Japanese market GT-Four were Cruise Control Package (Cruise Control and sunroof), SD Package (ABS, driver-side SRS Airbag, and Ultrasonic raindrop removal door mirror), and Luxury Package (10-speaker Super Live Sound System, Leather seats, and Wireless door remote control). However, the Cruise Control Package could not be combined with the SD Package. The cruise control and Ultrasonic raindrop removal door mirror could not be ordered without package.