Nissan Skyline HR31 GTS-R: The unsung hero of Nissan's first ATCC victory
“The HR31 didn’t have the biggest horsepower, it didn’t have anything special really, but it was just incredibly consistent,” said Fred Gibson reflecting on the car that played a decisive role in claiming Nissan’s first Australian Touring Car Championship in 1990 after nearly a decade of trying.
‘Whatever we qualified at and whatever time the car would do on the first lap it would do on the last lap and that’s where the HR31 was a real hero act. When the other cars particularly the Ford Sierras started to destroy their rear tyres and fall away, our cars just kept hanging in there.”
The HR31 GTS-R Skyline was Nissan’s second Group A warrior, which in 1988 had replaced the DR30 Skyline that Gibson Motor Sport had campaigned with considerable success since 1986.
Although the turbocharged 2.0 litre DOHC four cylinder DR30 (a hot coupe derivative of the R30 sedan) had been in contention to win the ATCC in 1986 and ‘87, it had narrowly missed out on both occasions.
The HR31 GTS-R with its purposeful-looking front and rear spoilers was a hot coupe derivative of the then latest R31 sedan. Launched in August 1987, it was built primarily as a homologation special to qualify for Group A racing with only 800 being produced.
The HR31 was powered by Nissan’s RB20DET-R turbocharged 2.0 litre DOHC in-line six. Equipped with a five-speed gearbox, it shared similar chassis architecture to the DR30 with MacPherson strut front and semi-trailing arm rear suspension.
Its homologated minimum weight for Group A competition was 1100 kg just like the turbocharged Cosworth-powered Ford Sierra RS500. However, as the Skyline was a heavier car, the best GMS could achieve was 1160 kg – 60 kg more than the Sierra which also had oodles more power.
In its first season of Australian touring car racing in 1988, the GTS-R failed to impress. Its late arrival meant it missed the first four rounds of the ATCC followed by a string of technical failures.
The Gibson team’s troubles were exemplified at Bathurst that year, when Nissan young gun Glenn Seton suffering a high speed crash at the pre-race media day. Then both cars dropped out of the race within 18 laps - one with a blown gearbox and the other with a cooked engine after it threw a fanbelt.
In 1989, with those early failures behind them, Gibson signed top gun Jim Richards as his lead driver, who immediately impressed with his speed and consistency. However, the HR31s were still not a match for the all-conquering Sierras which finished 1-2-3 in the ATCC and 1-2 at Bathurst.
Even so, the works Nissans were getting stronger. George Fury, in his last year with the team, used his renowned rally driving skills to win a wet and wild ATCC round at Winton. Richards and his rising apprentice Mark Skaife also won the Sandown 500 endurance race, after many of the Sierra teams suffered a myriad of problems.
Although Nissan’s surprise Sandown win shortened their odds of winning Bathurst, Fred Gibson’s men had to be content with their two cars finishing third and fourth and a lap behind the winning Johnson/Bowe Sierra which blew everyone into the weeds that year.
So after two seasons of taking a back seat to the all-conquering Ford Cosworth Sierra RS500s, Gibson Motor Sport’s prayers were finally answered in 1990 with the HR31’s much anticipated replacement – the awesome R32 GT-R.
Among the Japanese super coupe’s implausible specifications was a larger capacity engine with not one but two turbochargers, plus a six-speed gearbox and all-wheel drive with electronic torque split between front and rear wheels.
Unfortunately for Nissan, the complexity of the GT-R caused considerable delays in its construction and pre-race preparations, which postponed its debut until the fifth round of the 1990 ATCC.
This fateful timing left the Japanese manufacture with no choice but to soldier on with the HR31 into a third ATCC season and try to salvage as many points as they could until the GT-R was ready.
1990 ATCC: The rule change that changed everything
Although now a potent and battle-hardened warrior, the GTS-R with its ultra-reliable 440 bhp engine and tank-tough chassis package had pretty much reached the end of its development cycle.
For the third season in a row it faced another uphill struggle in trying to topple the Sierras, which were not only lighter than the Nissans but capable of power outputs as high as 700 bhp.
However, the stars finally aligned for Gibson when Australian motor sport’s governing body CAMS made a key technical change for the 1990 ATCC which gave Nissan more than a fighting chance.
A mandatory increase of 85 kgs was added to the 1100 kgs minimum weight for turbocharged cars, to address the obvious imbalance in performance between the Ford Sierras/Nissan Skylines and the naturally aspirated Holden Commodore V8s.
It was expected that the hefty increase of 85 kgs for the Sierras would have a greater effect on their performance than the Nissans, as most of the top Fords had been running at or close to their 1100 kg minimum in previous years.
By comparison, the GTS-R despite Gibson Motor Sport’s best efforts had never been under 1180 kgs so the small amount of ballast required to meet the new 1185 kg minimum would have a negligible effect on its performance. And on its tyre life, which was aided no doubt by its less powerful engine.
And given that each round consisted of one 50 minute race, which typically covered a distance of between 100 to 150 kms, the Sierra’s extra weight was going to place more stress on rear tyres that were already struggling to withstand the turbocharged Ford’s immense power and explosive throttle response.
It was a situation custom-made for the HR31 and Nissan’s star driver Jim Richards to show their true strengths. After joining the Nissan team in 1989, Richards - already a multiple ATCC and Bathurst winner - had a full season of racing experience with the GTS-R and had mastered what was required to squeeze the last drop of performance out of it.
He would also be fighting a lone hand in the early rounds as his younger team-mate Mark Skaife was dedicating most of his time and energy to testing and development of the new GT-R to get it ready for its belated track debut.
Richards’ performances in the eight-round ATCC were flawless. He took full advantage of the HR31’s attributes on the tighter and twistier circuits, with gritty determined drives to win the Amaroo Park and Winton rounds.
With points awarded for the first ten places in each race and with only the seven best results from the eight rounds counting for the championship, Richards kept piling up points at the high-speed tracks with two excellent third places to the faster Sierras at Phillip Island and Mallala.
A fighting fifth at Lakeside and seventh at Symmons Plains provided the springboard Richards needed when he got behind the wheel of the new GT-R for the final two rounds.
At Perth’s abrasive Wanneroo track he salvaged fourth place after suffering tyre wear in the new all wheel drive supercar, before blitzing the field at Oran Park’s final in a flag-to-flag win that secured the first title for Nissan in emphatic style.
SUBHEAD: How the HR31 GTS-R became a winner
Although never sold in Australia through Nissan dealers, the HR31 GTS-R coupe’s on-track success provided plenty of polish for the brand’s local credibility.
It was an effective marketing tool because the HR31 shared many styling and engineering cues with the locally-made R31 four door sedan and, most importantly, the Skyline name.
Gibson Motor Sport never gave up on its development of the HR31 over the three years it competed, including a switch from Dunlop tyres to a full factory deal with Yokohama in 1989.
The GMS Nissans were renowned as the fastest in the world, boasting a huge amount of local development that made them faster and tougher than factory cars racing in Europe and Japan.
The Gibson team developed and homologated many of their own components in Australia, including more robust front suspension strut assemblies that could withstand enormous punishment and use of the Australian-made Holinger five-speed racing gearbox in place of the Nissan-supplied unit that proved troublesome in the early races.
“We virtually did all the homologation for the DR30 Skyline because we wanted to design and use our own parts right from the start,” Gibson explained. “So when the HR31 came along, we just carried across things that we’d developed for the DR30 like uprights, suspension arms etc.
“The engine was completely different to the DR30, though, so it was a whole new engine program. Then we also had to convert our Electromotive (engine management) system that we put on the four cylinder DR30 with the Americans to the six cylinder HR31 Skylines here, so that was difficult to do as well.
“All the Nissan race cars since the (Group C) Bluebirds had independent rear suspension but that was their downfall because they were all pretty bad independent race cars. The thing that made the biggest difference was when radial race tyres came in during the DR30 days (mid-1980s).
“They really suited the rear suspension because what a radial tyre needs to work properly is a lot of static negative camber. It made a huge difference to the back of the car because the independent suspension had lots of negative camber in it, so we learned a lot from that and ended up running something like five degrees of negative on the front as well to make the radial work there too.
“We transferred all of that suspension knowledge to the HR31 but it was still not a great handling car. It was a very difficult car to get the handling right, but we just chipped away at it.”
Gibson is rightly proud of what his team achieved with the HR31 GTS-R, considering the car’s humble origins and how hard they had to work to make it a Sierra beater.
“The main thing to remember is that HR31 was never a race car like the Sierra RS500 and the BMW M3, so my instructions to my drivers were that you’ve got to drive the cars like you hate them; do whatever you have to do to go fast.
“That’s why our guys drove the wheels off them and were quite brutal with them. They never had the power of the Sierras, so they had to attack every race lap like a qualifying lap (to try to make up the deficit).
“Having said that, the HR31 did have consistent handling, good brakes, good tyre life and whatever you started with you finished with, whereas the Sierras would tend to fall away because they had so much grunt their rear tyres would start to melt after a few laps.
“The HR31 won ‘Richo’ the championship, without a doubt. The GT-R wrapped up the title at the final round and got all the glory, but the HR31 did all the hard work getting there.”