The Kangaroo Minis
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The Kangaroo Minis

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By JoeKenwright - 08 February 2013
By packaging a detuned Mini-Cooper as the volume-selling Mini De Luxe with wind-up windows, remote gearshift, luxury trim and hydrolastic suspension, BMC Australia could offer the hot Cooper S version at a modest premium under strict local content rules.

After developing the original Mini-Cooper version as the starting point for its unique Australian Mini range for 1965, BMC Australia could offer a local Cooper S version that was devastatingly effective and unexpectedly affordable.

Many Australians thought that the early Mini was a practical joke in 1961 with its tiny wheels, low hanging sump with its shared engine and gearbox oil, small boot, hard-working engine and crude sliding-window cabin. Against the odds, its 5426 end of year sales following its March 1961 launch had rocketed to almost 21,000 by 1963. To meet tough new local content requirements after 1964, BMC Australia, like Volkswagen, had to create a local specification that wouldn’t need costly annual changes. 

After Australian and US marketing carefully avoided any references to the Mini name with the first Morris 850 and Cooper in case either was perceived as anything less than a full strength car, BMC Australia could officially embrace the Mini name in 1965 after Australians had adopted it as a term of endearment.  As some of the world’s sexiest women embraced the mini-skirt, Mini soon became code for less equals more!

The cheap and cheerful local Sports 850 with twin carburetors and free-flow exhaust quickly demonstrated the Mini’s potential in 1961-62. Factory-approved, it was driven by Peter Manton’s BMC performance dealership in Elizabeth Street, Melbourne that specialized in local MG and Austin-Healey Sprite models. Manton was a pioneer in positioning the local 850 as more than just a cheap and cheerful runabout in the showrooms as well as the track.

With drilled wheels, extra gauges and carpet, this Mini De Luxe cabin shot would apply equally to the local Cooper S.

It took the first locally assembled Cooper to arrive late in 1962 to catch everyone’s attention. At a considerable cost premium ($1900 versus $1550), its bigger engine, front disc brakes and plusher interior was a better fit with Australian expectations and distances than the poverty packaging of the Morris 850. The remote gear shift, extra instruments, wheel trims, bumper extensions and classier grille had car spotters around the country on green alert. Spotting a definitive green example with white roof was worth bonus points. 

Its 997cc engine was BMC’s second go at producing a decent 1-litre version of the A-series engine. The Healey-Sprite featured a tuned version of the Morris Minor 1000’s 948cc engine for a tame 37kW/49.8bhp compared to the first Cooper’s 38.8kw/52bhp on a compression ratio lowered for local fuel with near identical weight to the Sprite. It had an instant impact on local race results. Because this Cooper engine was a longer stroke version of the 948cc version, it soon ran into longevity issues with its increased piston speeds. 

Meanwhile BMC in the UK had to act quickly to give its sports-luxury Riley Elf/Wolseley Hornet versions of the Mini a bigger engine to counter their extra weight. This led to a third 1-litre A-series engine, this one boasting 998cc after the 997cc engine’s bore was increased from 62.4mm to 64.5mm and stroke reduced from 81.3mm to 76.2mm. Released in single carburetor form with the same 8.3:1 compression ratio as the local Cooper, its development was especially significant to local Minis as it brought a big boost in torque and would soon address the 850’s noisy and busy engine room over longer distances. 

At first, a tuned 998cc engine was seamlessly fitted to the local Cooper in early 1964, delivering a freer-revving, longer-lived new engine just as the earlier version’s shortcomings were becoming apparent. By early 1963, the 1071cc Cooper S version had already displaced the Cooper as the Mini performance king globally. 

An early Cooper S Mk I. Note the early wiper location, the wider drilled wheels, the bumper overrider extensions but no wheel arch extensions.

Because this oddball interim Cooper S with its Formula Junior-derived engine had no place in BMC’s long term local plans, its short model life would have wreaked havoc in planning and pricing at the critical 1964 changeover point in local content. In the interim, it reached Australia as an import badged as a Morris or Austin and gave a generation of young drivers a head start on the track in the touring car categories. For BMC Australia, it would later deliver a pool of trackside expertise as soon as a local Cooper S was ready for production racing.

In mid-1964, BMC Australia announced a comprehensive list of engineering upgrades across the Mini range reflecting similar upgrades for the Morris 1100 as the first stage in preparing it for increased local content. Three months later, the local Cooper was given its third engine specification, this time a special high-compression version of the 998cc engine built locally as the first stage in a unique local Mini and Cooper heritage. 

Although new output figures were not widely released, the early-1964 version of the 998cc Cooper with the lower compression ratio brought a welcome boost in torque over the 997cc version but no power increase. It is fair to assume that the late 1964 high-compression version delivered a discernible torque boost and at least restored power to the 55bhp/41kW of the British 997cc Cooper. British figures showed that both the power and torque peaks arrived earlier. It was enough to allow the local Cooper to fill class podiums in production racing around the country after its high local content kept a lid on its new price. 

It was also a critical step in establishing credibility for the 998cc engine and the 1275cc Cooper S version that would soon define the new Australian Minis. 

The requirement for a more powerful engine for the heavier Wolseley and Riley versions of the Mini generated the perfect powerplant for the Australian Mini De Luxe.

 

1965-71: The Australian Cooper Years

Although the 850 would continue as a short-term entry model for another year or two, BMC Australia was about to build its mainstream Mini range around the Cooper. 

In March 1965, the first stage was announced as the Mini De Luxe followed by the Cooper S in September.  The plan was to build a single Cooper specification starting with the same grille, fluid-filled Hydrolastic suspension instead of rubber cones, remote gear change, wind-up windows and plusher pleated seats based on the original Cooper. By offering the choice of the Elf/Hornet-spec single carburetor 998cc engine in a Mini Deluxe version of the lighter Mini body or the hot 1275cc engine in a unique Aussie Cooper S derived from the same starting point, the Sydney company gobsmacked the Australian market with not one but two improved performance Mini models. 

The Mini De Luxe sold for just $1666. Significantly faster and more luxurious than the 850, it cost just $108 more.  The local Cooper S was offered at an unbelievable $2280, barely $380 more than the relatively tame 1962 Cooper. It also explains why local marketing often referred to the two cars as Mini De Luxe and the Mini S when they were more closely aligned than in other markets.

Because the initial September 1965 batch of local Cooper S examples was geared to homologating the model for Bathurst, they featured the special British Cooper S drivetrain in a body that had yet to feature all the local improvements. Its twin fuel tanks and oil cooler arrived several months ahead of the British model. 

The new range brought further engineering upgrades including bigger brakes on both models, key start, a diaphragm spring clutch, mechanical fuel pump on the Mini De Luxe, door operated courtesy light, multi-adjustable front seats with wing nut tilt adjustment, front three-point seat belts, and a heavily revised gearbox with needle-roller bearings on the mainshaft, new selector fork and wider, stronger teeth on the mainshaft gears. 

Missing on the Mini De Luxe were the Cooper’s bigger instrument pod, front disc brakes, carpets and bumper extensions. The Mini De Luxe price cut of almost $300 over the previous 998cc Cooper along with the wind-up windows, Hydrolastic suspension and better gearbox more than compensated.

The big winner was the Australian Cooper S. Because the shared interior was based on the first Aussie Cooper and current Mini De Luxe, its expanded-vinyl pleated seats with plump under-thigh bolsters, extra adjustment and matching carpet were very different from the UK version. The three point front seat belt mounting points were just as useful for racing harnesses.

This brochure shot shows a later Australian Cooper S Mk I with the revised wiper location that was introduced as a running change.

The wind-up windows were also a unique Australian development (exported to South Africa where they were combined with the British specification cars sold there).  

The Hydrolastic suspension, with its unique local underbody protective recesses and covers for its interconnected fluid lines, was given extra line pressure and thicker fluid to stiffen it for the Cooper S although the first cars missed out on the underbody recesses for the fluid lines. A Cooper S power booster allowed harder pads for the thicker and bigger diameter front discs while a pressure lock-up valve kept the fatter rear drums tidy. As Cooper S production settled into a long term routine, items like the heater and Girlock power booster were replaced with local bits.

Local radial ply tyres on wider 4 ½ inch drilled wheels were a local first. All local Minis during this period had clear front parking and indicator lenses when amber indicators were not yet required and amber parking lights were illegal.

The most extensive and expensive changes were under the bonnet, not just for performance but exceptional durability for the period. The new 1275cc engine was a further development of the Formula Junior 1100 racing engine which was quite different to the Morris 1100’s 1098cc engine. It therefore featured the same 70.6mm siamesed bores as the 1071cc Cooper S with its stroke lengthened to 81.33mm. The Morris 1100 engine featured the same 64.5mm bore as the Mini Deluxe’s 998cc engine with an even longer stroke of 83.72mm.

Because this allowed BMC Australia to power all its volume Mini and 1100 models using the same block, the special 1275cc Cooper S engine was the odd one out and had to be imported. A compression ratio of 9.75:1 was beyond what local fuels could handle and required a special fuel mix for its full 75bhp/56kW. The big valve head featured aluminium bronze guides for the higher revs. The nitrided crankshaft was made from billet steel with supersized conrod and main bearings that allowed it to rev all day providing you kept up with the oil consumption.

Although the gearbox was strengthened, it still had no synchro on first.

As an exercise in local production engineering and pricing for a market increasingly hostile to imports, it truly was an outstanding package. 

It didn’t end there. After the Australian cars bypassed the British Mark II facelift late in 1967 with its squared-off grille, a Mini De Luxe Auto was added in January 1968. This coincided with another change that occurred during 1967 that placed the local Cooper S further in front of the British version. A new scuttle panel at the base of the windscreen reversed the sweep of the wipers eliminating the blind spot at the driver’s eye level.

Cooper S police cars with their bigger carburettors and upgraded cylinder heads were a common sight in NSW and often equipped with driving lights, weather shields and sun visors. State government support for local factories would partly explain why the Cooper S was not picked-up by other states.

 

1969-71 The Australian Mini Mk II

It is widely assumed that local Minis caught up with the 1967 British Mark II in March 1969. Not so, as the local operation was still committed to its 1965 body details. The Mini De Luxe instead gained the Morris 1100 engine and was then re-launched as the Mini K, the K standing for Kangaroo. Slight changes in badgework, trim, a dished padded steering wheel, Cooper instrument pod, synchromesh on first gear and alternator were the main changes. 

The big gains in power and torque brought performance within a whisker of the original Cooper while the Hydrolastic ride and fuel economy were superior. It was the ultimate development of the all-Aussie round-nosed Mini, all for a price increase of just $20!!

By May 1969, a unique local Cooper S Mark II was added to the range, also gaining synchro on first gear inside the new Mini K gearbox casing. An elusive and distinctive little car, its oval bonnet badge, normally combined with the squarer British Mark II grille elsewhere, sat above the earlier semi-circular grille in Australia. There were plusher front seats, padded dash rails and wheel arch flares (which had been added to South Australian Mk I examples in 1967). It retained the bumper extensions, original tail lights, exposed hinges and earlier glass of the first Coopers.

By now, the local Repco-PBR VH44 power booster was fitted to all examples. Along with new heater controls and fittings, the Mini-K’s dished centre-padded steering wheel and combined indicator-horn stalk with its indicator warning lights moved to the dash, plus there was an extra muffler to tame the exhaust crackle, all for the bargain basement price tag of $2365. 

A British Cooper S Mk II interior highlighting the different seats and doors.

Because the expensive imported drivetrain remained intact, there was little margin for changes beyond what was required by new Australian Design Rules while keeping it within this price range. Leyland Australia knew its purist road and track market well, which by now included the NSW police force, and its unbreakable drivetrain under duress was still its primary asset.

Yet this wasn’t the last Aussie Cooper S. That honour belongs to an unusual final specification dictated by new Australian Design Rules in 1971. Again, it is incorrectly assumed to be a hybrid of later British Mark II and Clubman parts. 

From January 1971, there were strict new anti-burst requirements for the door locks and the traditional house-door style exterior handles were outlawed so they couldn’t spear pedestrians. To meet these requirements, a new centre pillar had to be engineered which dictated new body side panels. A new door design had to accommodate the different locking system as well as the new recessed lift-up exterior door handles. After the old style external door hinges were found to be strong enough to meet the new rules, they were left intact hence these changes were totally independent of the new hidden door hinge design of British Minis.

At the same time, strict new demister requirements applied and for the first time, a proper heater-demister system with a strong fan-booster function within a new plastic assembly was fitted. The Cooper S heater-demister system required special twin-pipe fresh air plumbing different to the Mini K to clear the big power booster under the bonnet. Yet apart from these tweaks, the body design remained faithful to the 1965 specification as defined for long term local production.  Unlike the British Minis which reverted to the earlier rubber cone suspension, the Australian Mini-K and Cooper S featured Hydrolastic fluid suspension until the end. 

Total production for this proud local Cooper S heritage included 4986 Mark I examples and 2419 Mark II examples, of which a tiny fraction was the 1971 ADR special. 

The Cooper S engine bay was crammed with twin carburettors, brake booster and extra plumbing for the oil cooler.

 

What an Australian Cooper S should have

Like the XU-1 Torana and Falcon GT, you can be fooled by a fake Cooper S based on a Mini De Luxe. These are some of the tell-tale bits:

Early Australian Cooper S examples featured some UK-type pressings including the floor that left the Hydrolastic lines proud of the floorpan. These were only covered by plates front and rear of the floor hence the rest was exposed and prone to damage. In later Mk I examples they were fully recessed into the floor and fully covered by plates.        

There were additional straps for the fuel vapour pipes on the panel in front of the fuel tanks as viewed from the boot. There should be two for each tank in the vertical section and three across the top. On very early Mk 1 examples, plastic clips located the vertical section of the vapor pipes which exited through the floor. These pipes did not cross over so that each breather exited on the same side as the tank. later Mk1 examples, the vertical straps were metal and spot-welded in place (not pop-riveted). The RHS tank must have a support bracket that was also spot-welded. 

There should be two holes in each side of the boot floor. On the LHS, one each for the fuel vapour pipe and fuel supply hose and on the RHS, one each for the battery cable and the second fuel vapour pipe. 

On the first Mk1 examples, the oil cooler was located under the generator at 45 degrees.  Its metal pipes were prone to cracking and many had to be replaced under warranty with a BMC kit.  Later cars had a recessed front apron for the oil cooler with a spot-welded diagonal support brace instead of vertical.

For the Australian Cooper S Mk II, the British Cooper S Mk II badge was applied to the earlier Australian Mk I body style which by now featured the revised wiper location and standard wheel arch extensions. Note the correct clear park/indicator lights which were amber in other markets.

Early examples had the Girlock power booster before the Repco-PBR VH44 booster became the long term fit.  Early cars also had a larger capacity full metal brake master cylinder tank. Later cars relied on a plastic extension to boost the capacity of the standard size tank master cylinder. The brake pedal was beefed-up for harder linings in the 7 ½ inch front discs and wider rear drums.

The twin 1 ¼ SU carburetors (boosted to 1 ½ inch on police cars with cylinder head work to match) featured an oval air filter assembly that housed two round air filters. Unlike the Mini-Deluxe, the Cooper S had an electric fuel pump mounted on the LHS sub-frame with a fuel breather valve under the rear seat on the same side. 

Early instrument pods were 850 binnacles with a metal faceplate that located the gauges on each side then covered by a plastic shroud. Later cars had a full one-piece cluster specific to the Cooper S. A tachometer was a glaring omission with gear change points on the special 130mph speedo only partial compensation. Look for the covered dash rails, solid chrome top ashtray in the dash rail and the metal heater assembly.  

Apart from the plastic heater assembly (some police cars also had a handbrake warning lamp and reversing lamps) and the 120mph speedo, the Mk II was more of the same.

As for the special 1275cc Cooper S engine and Australian-build, there are special numbers to identify the local Cooper S along with identifiers around the engine to distinguish it from other 1275cc A-series engines. 

 

References include OZ Cooper, The BMC Experience, Wheels and Modern Motor magazines 1962-71, period brochures and some of the many passionate Australian Mini fans.