The passage of time has served to obscure the Toyota Celica GT-4 ST165’s significant place in WRC history, and we think that’s a shame. For all its faults (and early on there were plenty to pick from) and at times maddening unreliability, the ST165 Celica was the first Japanese car to beat the established European teams on a consistent basis. It very nearly took to Toyota to its first ever constructors’ title and enabled Carlos Sainz to claim his maiden Drivers’ championship, not forgetting a British Rally Championship for Dai Llewellin.
Perhaps more importantly from a sporting perspective, the ST165 effectively routed the Lancia Delta Intrgrale, or at the very least ensured that it was no longer a foregone conclusion that the men from Turin would be stood at the top of the podium come Sunday evening!
We’ve touched upon the role Group A played in the rise to dominance of the Japanese car makers here before, and Toyota was no exception – despite having signed off the advanced Group S MR2 project 2 years previously. Willing to partake it might have been, but Toyota made little secret of its preference for road-based cars with clear links to the forecourt fodder being flogged throughout the dealer network. The banning of Group B therefore acted as bait, luring the company into fully committed, multi-million pound rally programme and setting the stage for the brilliant ’90s squabbles we came to know and love.
The Group S project did at least give Toyota (well, TTE) a solid foundation on which to build its new, Celica-shaped Group A car, and this was reflected in one of the project’s defining traits, its active Xtrac-penned active centre differential. Mike Endean’s systems had proved their worth in the previous decade, effectively taming the likes of Martin Schanche’s Escort Rallycross and John Welch’s Astra, both of which had demonstrated that there was now another, more nuanced way of getting a four-wheel drive car to handle off-road.
The tech underpinning the TTE-Xtrac system was fairly jaw-dropping, certainly for the late ’80s. The hydraulically actuated centre ‘diff could split torque to the front and rear axles to take changes in acceleration and braking into account, while the handbrake was configured to automatically revert the system to a 28:72 ratio ideal for tackling tight corners. It was a far, far more polished means of splitting drive than anything seen beneath a Delta, and pointed the way to the cutting edge differentials which would come to define World Rally Cars in the decade that followed.
Advanced it might have been but the Xtrac system was initially nothing but bothersome, prone to sending sudden stabs of torque to either end with little warning – with predictably disastrous results. The issue, eventually traced to a software fault, was finally put to rest as the ’80s gave way to the ’90s, but not before Juha Kankkunen (the ex-Lancia man who’d taken the plunge with TTE in 1989) had had quite enough and re-de-camped to Lancia.
While its transmission grew to become the envy of the service park and undoubtedly one of the car’s ‘trump cards,’ the Celica also showcased clear evidence of Toyota’s relative inexperience at the sharp end of the WRC, with a story from David Williams proving especially telling. The highly respected rallying journo relates one of TTE’s attempts to keep the Celica’s hard-working engine cool by re-locating the indicators to the side lights. The resulting holes horrified the Toyota ‘top brass’ back home in Japan, and a pair of blanking plates were swiftly manufactured, both of which were in place when the Celica came to be homologated.
The addition of these beautifully designed, incredibly innocuous looking plates had a dramatic impact on the Celica’s subsequent performance, making the new car susceptible to overheating.
This lack of communication and understanding between TTE and Toyota would have dramatic consequences. The tight wording of the Group A regulations ensured that, while painfully aware of the cause of the Celica’s subsequent shocking reliability, TTE’s engineers were restricted in what they could do to cure it. It meant that Works Toyota drivers were destined to spend the ’88 to ’91 seasons with one eye glued to the temperature gauge, well aware that a dramatic drop-off in performance (at best) was at stake if needle strayed too far into the red.
Excess heat could also lead to engine failure, while it was also found that the Xtrac system, very much the ST165’s trump card, was less than happy functioning in scorching hot conditions.
Rally engineers are nothing if not resourceful though, and with their collective back against a wall and WRC wins potentially at stake, TTE’s set about devising a partial solution to their cooling woes. Big strides in intercooler efficiency would ultimately come closest to curing the problem once and for all (and this despite the ‘cooler being located in a less than handy position, atop the engine), but not before the team had trialled an increasingly creative set of solutions.
The first was the most logical; the team simply redesigned the front headlamp units of the Celicas used in ’88 and ‘89, replacing the ‘pop-ups’ of the road car for smaller, fixed examples. Not only did the fitment of these constitute a minor weight saving, their more compact dimensions allowed a small stream of air to pass into the engine bay unimpeded. The lights provided a fractional advantage at best however, and in case, Toyota’s rivals were swift to voice their displeasure at the move, citing the clear differences between TTE’s competition machines and those produced for the initial homologation run.
1991, and by this point TTE had begun to get a little more creative. The most obvious instance occurred on the Safari Rally, where a specially designed lamp pod sprouted from the bonnet of the Works cars. (Incidentally, this was also the same event as the even more thermodynamically challenged Nissan GTI-R made its competition debut.)
Much was expected of the ST165 in East Africa, and not merely because Waldegard had driven one to victory 12 months previously. Works Toyotas were expected to win on the Safari, it’s just what they did; generations of Celicas had built the firm’s sporting reputation on the twin virtues of strength and reliability.
Things initially appeared to be sticking to script, Sainz driving in a measured manner to carve out a handy lead from the chasing Delta of Kankkunen. He looked set for a sensational victory until, mere miles after the restart at Eldoret on the penultimate leg of the rally, his engine temperatures soared. It didn’t take long for things to reach critical levels and even less time for the block to crack, forcing the lead Celica into retirement. A deeply frustrated Sainz could only watch as this team mates cruised home to a muted 2nd (Ericsson) and 4th (Waldegard) respectively.
Other, less finessed attempts to prevent the 3S-GTE from poaching itself were trialed at various points that year, the most obvious being a tendency for the Celicas to compete with their bonnets ever so slightly ajar. The overall effect might have looked a tad crude by the WRC’s high standards, but there was no denying that this configuration enabled a greater volume of air to enter the engine bay. It also appeared to be an effective short term fix; Sainz took victory in Greece and Argentina whilst at the wheel of a ST165 with a flappy bonnet.
Sainz would ultimately lose out to Kankkunen in the race for the 1991 Drivers’ championship, a scant, 7 point deficit enough to give the Lancia man his third title. The Celica’s twin retirements in Africa and again on the opening leg of the inaugural running of Rally Spain (an ECU glitch) had proved very costly indeed.
Initially troublesome it might at first have been, but the ST165 was eventually engineered to to become one of the most successful rally cars of the early ’90s. It won 12 international rallies over the course of its 3 year career, plus the 1990 title for Sainz. More significantly, the Celica proved that the Japanese had what it took to best Lancia at its own game and encouraged the likes of Subaru and Mitsubishi to up their respective WRC programmes, meaning it effectively laid the foundations for the present, multi-national championship we now enjoy.