The Torana GTR XU-1 shattered the American muscle car theory that high performance was only measured in cubic inches. Shoehorning a 3.0 litre six from a large car into a small one was not only bold but also marketing gold for Holden, because the XU-1 just couldn’t lose in the public’s eyes. When it lost to a larger car, it was courageous. And when it won, it was a giant killer!

How the XU-1 went from inspired thought to a super successful race and rally car is a testament to the lateral thinking of GM-H management and Holden Dealer Team boss Harry Firth. And to the local company’s determination to keep its clandestine racing program alive, despite GM’s global ban at the time.

The key men at Holden that made it happen were national sales director John Bagshaw, his deputy and race team liaison Peter Lewis-Williams and American-born chief engineer Bill Steinhagen. In an interview with AMC magazine in 2006, Lewis-Williams reflected on a crisis point for GM-H in determining the racing future of its big V8-powered HT Monaro GTS.

 

“The rules at the time (Series Production) were that you raced what you sold and a very big turning point was the release of the Falcon GT-HO in 1969,” he said. “Looking ahead, the big concern for us was that to run with the GT-HO, we’d have to ‘out GT-HO’ the GT-HO.

“I can very clearly remember a meeting in Bill Steinhagen’s office just after the 1969 Bathurst race, when we were discussing the way to go for 1970. Steinhagen said, ‘look, I’m just not prepared to release a car (Monaro) that will out GT-HO the GT-HO, because it also has to be sold to the general public for road use’ and ‘Bags’ agreed with him. Then Steinhagen said, ‘however, I think we can piece together a revamped version of the six cylinder Torana that will tackle the issue a different way.”

So Holden shocked everyone by dumping the US-flavoured Monaro in favour of a hot version of its new home-grown LC six cylinder Torana. While many racing ‘experts’ scoffed at such an audacious plan, the decision made sense for several reasons.

By sharing many existing components common to the company’s full-size HT family sedan range, the costs of building and competing in such a car would be far less than a full-house Monaro GTS, with its heavy reliance on expensive imported US parts. And such a Torana could be sold at a retail price far below that of a Monaro, which presented a much stronger business case.

Holden would also have a top class contender in both rallying and at Bathurst, where the Torana would be able to more than hold its own against price-based class competitors like Chrysler’s VG Valiant Hemi Pacer and Ford’s Escort Twin-Cam. But Holden was looking beyond just Bathurst class wins. The switch to Torana would conveniently stop GM-H getting dragged into an unpalatable ‘supercar’ war with Ford by taking a more scientific approach to defeating the GT-HO on outright terms.

With appropriate engine and chassis modifications, it was calculated that a hot Torana six could not only offer a superior power-to-weight ratio to the Monaro but enjoy the numerous additional performance benefits over its Falcon rival of a much lighter weight (about 400 kg less), much smaller overall size for less aero drag, superior agility and handling, plus greatly reduced tyre wear, brake pad wear and fuel consumption. That was all great in theory, but could this little car really deliver?

1970 LC GTR XU-1 (3100X)

Holden’s new Bathurst contender was launched in July 1970.  Harry Firth had been deeply involved in the XU-1’s design and development from the start, working closely with Holden management to stretch the performance envelope as far as such a conservative company (with a global ban on racing remember) would allow.

As the XU-1 was based on the much milder LC Torana GTR, it shared the same two-door body except for a new fibreglass spoiler attached to the rear of the boot lid and a new steel front spoiler attached to the splash guard beneath the engine. Firth’s AMC memoirs about developing this crucial device, which had never been fitted to a new Holden, display Firth’s pragmatic approach to vehicle development.

“During early testing of the prototype, I was driving along at high speed out near Digger’s Rest (Victoria) and there were three humps on the highway which were similar in size and shape to those on Conrod Straight at Bathurst. At about 125 mph (200 km/h) the nose of the Torana came right off the ground over those humps, so I fitted a temporary full-width front spoiler which immediately fixed the problem. However, it then looked like a race car which GM-H would not accept.

“The problem was solved when one of Charlie Patterson’s boys (Chassis Dept) fitted one underneath the nose on the under-tray between the front wheels. Rather than call it a front spoiler though, we called it a ‘wind deflector’. It also couldn’t be seen, which kept the hierarchy happy. We also lowered the front of the car to the minimum allowable ride height, which made it more effective. It was quite sufficient and by making it at an angle (V-shape) it also spilled air out onto the front brakes to keep them cool.” Not surprisingly, the rear spoiler was also called a ‘wind deflector’.

The front suspension was further modified for racing by lowering the upper control arm pivot shaft mounting in the cross-member. This was a tweak common in GT-HO Falcons, too. The lower pivot point for the top arm effectively shortened its reach, resulting in a lot more negative camber on the front wheels for greater cornering power.

The solid front brake disc rotors were also increased in thickness to combat heat-induced rotor distortion under racing conditions. The internal dust shields were also removed for better cooling and the single power booster was replaced by a tandem unit, to reduce the brake pedal pressure required.

A much larger 17-gallon (77-litre) fuel tank replaced the GTR’s tiny 10-gallon unit, to allow the XU-1 to get through Bathurst with only two fuel stops.

The GTR’s 161S engine was replaced with the largest and most powerful six cylinder Holden engine available at the time, the 3048cc 186S which in single two-barrel, hi-comp 145bhp spec had replaced the twin-carb X2 in mid-1967. However, for this application it carried engine prefix 3100X (or 186X) and was clearly redesigned with motor sport in mind.

A new cylinder head based on the 161 cid engine featured a stronger valve train, higher compression, bigger valves and a hot camshaft matched to a new cast aluminium inlet manifold with three 150 CDS Stromberg side-draught carburettors. There was also a revised ‘big bore’ free-flow exhaust system, heat shielding between the carbs and exhaust manifold plus a heavy duty radiator and low drag cooling fan.

The smaller case battery and tray from the four cylinder model was specified for the XU-1, primarily because the front Stromberg carby and its air filter canister wouldn’t clear the standard battery and tray. Of course, the additional benefit of this change was less weight over the front wheels.

The alternator drive pulley was increased in diameter to reduce the alternator’s rotational speed at the higher engine revs used in racing. Without this simple but effective change, the alternator bearings would turn molten real quick.

The GTR’s German-made Opel four-speed gearbox (M20), which was shared with the six cylinder  Monaro GTS, was considered strong enough for the task. A choice of two diff ratios - 3.36:1 and a taller 3.08:1 - was available for the banjo live rear axle’s cone-type LSD.

All this fine tuning work resulted in a healthy 35 bhp boost at higher revs over the GTR, with 160 bhp (119kW) at 5200 rpm and a crucial 40ft/lb increase in torque to 190 ft/lbs (257 Nm) at 3600rpm. Combined with a feather-like 1030 kg kerb weight, this potent power train sliced a full second off the GTR’s standing 400m blast, with magazine tests at the time recording a best quarter-mile pass of 16.1 seconds and a stunning top speed of 125 mph (200km/h). 

Whilst no doubt impressive figures, on face value Holden’s ‘David’ still paled against Ford’s ‘Goliath’ - the XW Falcon GT-HO Phase Two - which with 5.8 litre Cleveland V8 grunt could torch the standing 400m in mid-14s and was expected to top 140 mph (225 km/h) on Conrod Straight.

The underdog goes belly-up at Bathurst

“We went into our first Bathurst (1970) with the XU-1s full of confidence and with a genuine crack at winning the race outright,” Firth recalled. “We knew the Fords, particularly the works cars, would be faster than us in qualifying. However, we also knew that we could race all day at our qualifying pace but that the Fords would have to come right back to us in race trim because of the amount of fuel they had to carry, the harder tyre compounds they had to use and the fact they had to nurse their brakes the whole way.

“They also needed to change tyres during their stops because the Detroit Locker diffs they used really murdered the rears.  However, we could run the full race distance on one set of tyres, with our much lighter weight and smoother cone-type limited slip diffs. This was a critical advantage because in those days it took longer to change wheels than refuel a car.

“Like the Fords we had to make two fuel stops but we could refuel much quicker than them, with only 17 gallons (77 litres) to tip in compared to their 36 gallons (164 litres) through single filler necks. With all these factors on our side, we calculated that we could push the Fords very hard early on and with sustained pressure we’d break them.”

As expected the new XU-1s were all over the GT-HOs as famously demonstrated by Colin Bond when he shot past Moffat under brakes at the end of Conrod Straight on the first lap of the race to take the lead.

By quarter distance Moffat was back in front, but with the HDT Toranas of Bond and Brock/Morris not only leading their class but hounding Moffat in second and third outright and looking very threatening. However, valve failures caused by a simple manufacturing fault soon shattered the factory Torana attack, allowing the two works GT-HOs of Moffat and Bruce McPhee to cruise home in first and second places.

Sure, the XU-1 didn’t win Bathurst on debut, but it didn’t disgrace itself either. Sydney’s Don Holland, in a privately entered XU-1, not only won Class C but also finished third outright a lap behind the two works Fords.

The XU-1s were clearly a growing threat to the Falcons, particularly in the five long distance races which made up the newly announced 1971 Australian Manufacturers Championship. The HDT Toranas got off to a flying start, with Brock finishing second in round one at the Easter Bathurst meeting before Bond and Brock delivered a 1-2 in the second round at Warwick Farm. And there was more to come.

1971 LC GTR XU-1 (CK) ‘Bathurst’

A refinement process resulting from extensive racing and rallying through the later part of 1970 and early 1971 had allowed GM-H and HDT to weed out any weaknesses and determine what was needed to give The General’s ‘pocket rocket’ its best chance of winning Bathurst.

This process culminated in a special batch of LC GTR XU-1 ‘evolution’ models equipped with Holden’s latest Bathurst package. This limited production run (299 units) occurred between August and November 1971. The former 3100X or 186X engine number prefix was replaced by the letters CK - the ‘C’ identifying the model application ‘LC’ and the ‘K’ identifying the new engine specification, which included numerous upgrades to increase power and durability.

A new cylinder head assembly boasted carburettor and valve train refinements plus a more aggressive camshaft. Piston rings were also revised and lubrication was improved with a new ‘hinged gate’ sump baffle design and lowered oil pump pick-up to combat surge. A revised exhaust increased power and a thicker radiator boosted cooling in this higher-revving Bathurst engine.

All these revisions resulted in a useful 20 bhp increase for the CK over the 3100X, with a claimed 180 bhp (134 kW) at 6000 rpm (versus 160bhp at 5200rpm) and a small increase in torque at higher revs with a claimed 195 ft/lbs (264 Nm) at 4200 rpm (versus 190 ft/lbs at 3600rpm).

The CK XU-1s also blooded Holden’s new ‘Aussie’ four-speed gearbox, which was the existing Opel-based M20 unit fitted with a revised close-ratio gear set. This was also used in the 1972 LJ XU-1 and is often confused with the venerable M21 Aussie four-speed. A tougher clutch plate was included to cope with the CK’s greater power and potential increase in clutch abuse due to its taller first gear.

Oil baffles were also fitted to the inner ends of the rear axle tubes, to prevent excessive oil surge during high speed cornering from starving the diff. CK suspension was also toughened up with a new front lower control arm heavily reinforced around the ball joint mounting, to stop the arm bending under hard cornering loads - an early XU-1 racing problem.

There were also new steel wheels with thicker centres, as XU-1 wheel failures in racing were common in the early days and Holden would not approve Firth’s request for much stronger and lighter one-piece alloy wheels to fix the problem. Well, not yet anyway.

The CK XU-1’s taller first gear made it a little harder to launch from a standing start, but magazine tests of the era claimed a best 400m time of 15 seconds (a full second faster the 3100X) with most runs averaging mid-15s.

Engine redline was now 6500 rpm (versus 6400 rpm) and top speed increased to 130 mph (209 km/h) at 6250 rpm (versus 125 mph at 6000 rpm). Most impressive - but Ford had a big surprise waiting for the Toranas at Bathurst in the form of its third phase of the GT-HO program.

Despite the CK XU-1’s many engine, drivetrain and suspension refinements, it was impossible to compete with the XY Phase Three’s immense power on a circuit like Mount Panorama. Allan Moffat blitzed the competition, winning the race by a lap from two more Phase Threes in second and third.

However, the uprated XU-1s weren’t totally outgunned, as Class C winner Bond claimed fourth outright on the same lap as the second and third-placed Falcons. The CK XU-1s also finished what the 3100X models had started, by winning two more rounds to wrap up the inaugural 1971 Australian Manufacturers Championship for Holden in fine style.

The LC XU-1 also proved to be a brilliant rally car. Its light weight combined with a powerful engine and sharp handling response made it a formidable forest racer. HDT also welded lengths of 3/8-inch steel rod reinforcement throughout the body shells to hold them together, along with two-pack expanding foam (or ‘bread as Firth called it) to fill all the chassis members and lower sills for even greater strength and rigidity. These things were tank-tough.

The LC XU-1’s rallying achievements were emphatic, with Colin Bond and George Shepheard winning the 1971 Australian Rally Championship, Dulux Rally and International Southern Cross Rally to name a few. And its dominance was destined to continue with the more powerful LJ.

1972 LJ GTR XU-1

In February 1972 Holden launched its face-lifted LJ Torana range which continued to share componentry with its full-size sedan sibling, which in this case was the HQ series. 

The LJ GTR and its competition-bred XU-1 offspring were given a boost in engine capacity with the HQ’s new 202 cid (3.3 litre) six. The GTR got the standard donk but the unique XU-1 version was served much hotter with the LC XU-1’s well developed 186 cylinder head plus higher compression, more aggressive camshaft profile and a trio of larger Stromberg CD-175 side-draught carburettors.

More powerful than its predecessor, the LJ XU-1 was factory rated at 190 bhp (142 kW) at 5600 rpm and 200 ft/lbs (271 Nm) of torque at 4000 rpm. The close-ratio M20 gearbox introduced in the late 1971 CK Bathurst cars was carried over, as it was considered tough enough to cope with the mild increases in power and torque of the larger 3.3 litre engine.

Given the LJ XU-1’s slight kerb weight increase to 1048 kg its performance was similar to that of its LC predecessor, with a standing quarter of just over 16 seconds and a top speed of 125 mph (200 km/h). However, in fully blueprinted and balanced form, like HDT’s Series Production race car, the LJ XU-1 could scorch the standing quarter in less than 15 seconds with a scintillating top speed of 135 mph (217 km/h).

The new XU-1s continued to make life hard for the Falcon GT-HOs in early 1972 sprint races, but all eyes were focused on winning Bathurst. Ford was well advanced with its GT-HO Phase Four program, based on the latest XA Falcon GT sedan.

And behind the scenes Harry Firth and GM-H had also been hard at work on a definitive response, which was to shoehorn Holden’s compact 308 cid (5.0 litre) V8 into the LJ XU-1. With M21 gearbox, Detroit Locker diff, 13 x 6-inch Globe Sprintmaster alloy wheels, long range fuel tank and aerodynamic aids, the proposed XU-1 V8 would have been a genuine 160 mph (256 km/h) supercar that could easily have outgunned the GT-HO at Bathurst.

Sadly, like the Phase IV, the XU-1 V8 was killed off in June 1972 by the politically motivated and media driven ‘Supercar Scare’ when only weeks away from production. Like Ford, Holden planned to build a batch of 200 to meet the race rules, so what could they do with 200 sets of alloy wheels?

1972 LJ GTR XU-1 1972 ‘Bathurst’

In August and September Holden built a special batch of what have since become known as the 1972 ‘Bathurst’ XU-1s. These were fitted with the uprated springs and 13 x 6-inch Globemasters alloys intended for the XU-1 V8, plus a lightened flywheel, wilder camshaft which raised power output to 225 bhp, Detroit Locker diff and a finely matched 3.55:1 final drive ratio.

Had it been dry at Mount Panorama in 1972, the GT-HOs with their new 15 x 7-inch alloy wheels (intended for the Phase IV) and V8 grunt advantage would most likely have continued to trounce the Toranas. It certainly looked that way after dry qualifying, with Moffat on pole more than three seconds faster than his stunning 1971 pole time and GT-HOs filling the first four grid positions.

However, the gods smiled on Holden that weekend when heavy rain started to fall on race eve and continued well into the morning. This was a golden opportunity for Peter Brock and he seized it with a set of super sticky hand-grooved Dunlops fresh from Japan. Team-mate Colin Bond did not have the same rubber and paid the price, when his XU-1 aquaplaned off the circuit and rolled.

The Ford teams were also in a quandary over tyre choice with the big Falcons wobbling around like elephants on ice-skates. The wet weather, combined with improved brake ventilation from the new alloy wheels, caused the Falcons’ front brake pads to run too cool and disintegrate. With the Ford challenge effectively finished, Brock powered home to a famous giant-killing triumph.

The LJ XU-1 with its more powerful 202 cid engine also continued to dominate the local rally scene, with HDT Toranas winning the 1972, 1973 and 1974 Australian Rally Championships and numerous other major events. The XU-1 is unquestionably Australia’s most successful home-grown rally car.

1973 LJ GTR XU-1 1973 ‘Bathurst’

Holden still had one more major upgrade in store for the XU-1 when new ‘Group C’ touring car rules were introduced in 1973. These allowed for limited modifications to improve the performance and durability of road cars in competition.

To take full advantage, Holden built another small batch of homologation specials in August which have since become known as the 1973 ‘Bathurst’ XU-1s. These cars were the ultimate development of the breed, with far too many detailed engineering upgrades to list here.

Suffice to say they were loaded with special parts earmarked for Group C racing which included a stronger and more powerful engine, big breathing inlet manifold, tube-type extractors, close-ratio gearbox, stronger rear axles, bigger brakes, additional body bracing and lots more.

As a result, HDT’s 1973 XU-1 Bathurst cars were sensational. With around 245 bhp from their triple-carbed sixes, they combined a formidable power-to-weight ratio with a huge boost in grip levels thanks to Group C’s much greater wheel and tyre widths.

The works XU-1s were demonstrably superior to Ford’s new XA Falcon GT Hardtops in winning the five-round 1973 Manufacturers Championship, claiming victories at the Sandown, Surfers Paradise and Phillip Island rounds. Brock and co-driver Doug Chivas were also on target for another Bathurst win until a critical miscalculation resulted in the car running out of fuel and having to be pushed uphill into the pit lane by Chivas alone, without any outside assistance. This agonising delay cost HDT the race.

The XU-1’s winning ways officially came to an end in 1974, after Brock and HDT switched to Holden’s new V8-powered LH Torana SL/R 5000 for the final two rounds of the Australian Touring Car Championship. Although these wins sealed Brock’s first ATCC title, the trusty XU-1 he drove to victory in three of the earlier rounds was crucial to his success. So, just as the brilliant Torana GTR XU-1 had won its first race, it also went out a winner.