Mini masterclass: from Cooper to ERA Turbo

By Simon Charlesworth

| 30 Apr 2024

Classic & Sports Car – Hot Minis: Cooper ‘S’, 1275GT, ERA Turbo and more

What could be better than a Mini?

A car that, in 1999, Classic & Sports Car readers – plus a panel of experts – honoured as ‘the greatest of all time’.

A marvel of packaging so smothered in plaudits that its status has risen from runabout to something closer to a constituent of British folklore.

The answer? A quick Mini.

The Morris Mini Cooper MkI (left) and the MkII Cooper ‘S’ handle beautifully, with great roadholding

Once BMC’s belittler of bubble cars was on the loose, it was but a blink before the 10ft marvel ventured onto race tracks and rally stages.

Its handling prowess took even its designer Alec Issigonis by surprise: “A low centre of gravity, good weight distribution, and suspension which comes near to the theoretical ideal led us to hope for exceptional handling qualities – but the results exceeded expectations.”

Here, ready to lure the unsuspecting into a minefield of references to The Italian Job are the various breeds of officially sanctioned quick Mini; a concept that would be revisited by the car’s parent company almost as frequently as it would change its name.

BMC sold nearly 25,000 MkI Morris Mini Coopers between 1961 and ’64

Among those inspired by the new car’s early motorsport forays was John Cooper.

In addition to revolutionising post-war Grand Prix racing, Cooper had experience in both international Formula Junior and modified road cars, in the shape of a Climax-powered Renault Dauphine.

Cooper saw the Mini’s potential, and it just so happened that his Formula Junior cars were powered by works A-series units.

The Morris Mini Cooper is powered by a 997cc four-cylinder engine with 55bhp

He got hold of a former press demonstrator, to which was initially fitted a 100bhp 948cc A-series and 7in Lockheed front disc brakes.

After experimenting with a 994cc unit, Morris Engines’ Eddie Maher settled on a 55bhp 997cc with a modified cylinder head and cam profile, large inlet valves, higher compression ratio and twin SU HS2 carburettors.

The car went down a storm with all who drove it.

Yet the notion of a quick Mini being officially offered via BMC’s showrooms very nearly didn’t happen.

‘The Mini Cooper is all about building, maintaining and dancing with speed’

When Cooper approached Issigonis, who was technical director of Morris Engines, with a request to build a homologation run of 1000 cars, he was refused.

The decision was only overturned by Cooper persuading Issigonis’ equally doubtful boss, Sir George Harriman, to build the car in July 1961.

They paid John a royalty of £2 per Cooper sold.

In a worrying demonstration of how disconnected BMC management had become from the market, far from struggling to shift 1000 of them, 24,860 had been sold by the end of 997cc production in 1964.

The Mini Cooper ‘S’ MkII’s familiar, well-packaged interior

A-series rationalisation meant that the engine was superseded by the shorter-stroke 998cc unit at the end of 1963.

In September ’64, Hydrolastic suspension replaced the original solid rubber cone set-up; this expensive and arguably less convincing system would last until the final MkIII Cooper ‘S’ was built in mid-1971.

In October 1967, BMH introduced the MkII Mini, which featured a raft of tweaks – but it would last only until BLMC dropped the lesser Cooper in late ’69.

The Mini Cooper ‘S’ MkII packs a 75bhp punch thanks to its 1275cc A-series engine

Lesser Cooper? Since 1962, the racing team had been running an 1100cc A-series in its Formula Junior T59.

A rev-limit of 7800rpm and power of 98bhp was deemed a trifle hot for a road car, so was cooled down by Maher.

Launched in April 1963, the Cooper ‘S’ – with its 70bhp 1071cc unit – gave the Mini a useful boost in Group One racing.

In March 1964, BMC replaced the 1071cc ‘S’ with the 65bhp 970cc variant that was launched alongside the final and fastest ‘S’ – the 75bhp 1275cc.

John Cooper had to put up a fight to get sporty Minis into showrooms

This ultimate evolution would be the only Cooper to be produced post-March 1970 as a MkIII – in a 15-month, 1570-car run – before BLMC axed its UK association with Cooper.

By then, the ‘S’ had competition from a younger-looking sibling in the form of the lower-priced, slower-paced 59bhp 1275GT.

Arguably more of a replacement for the Cooper than the ‘S’, the GT’s 1275cc capacity made comparisons with the latter inevitable.

Morris badging on the Mini Cooper ‘S’ MkII’s small, chunky steering wheel

The 1275GT was the fastest of the Clubman range that was introduced in 1969.

Designed by Roy Haynes and Paul Hughes, it moved the model upmarket, replacing the defunct Riley Elf/Wolseley Hornet while also updating the 1959 alumnus in the face of supermini competition.

It boasted better crash protection and a more comprehensive, ergonomic dashboard, but that boxy Maxi-enstein nose did look incongruous.

Compare and contrast the Coopers and the 1275GT in chronological order, and the differences are notable.

Don Mitchell’s featured MkI feels roomier, lighter (in both senses) and less refined – that lower final drive (3.765:1 versus the 3.44:1 of the ‘S’ and 1275GT) highlighting the frenetic nature of the 997cc unit.

The Mini Clubman has a redesigned front end that’s squarer than the standard model’s

Inside, you’re never alone with the heckling from the A-series overdubbed with the unmistakable scream of its idler gear.

Accelerate, do your best with the gristly four-speed gearchange and you’re awash with gruff noise.

The large two-spoke wheel scarcely needs any noticeable manual input to navigate gentle flowing roads.

Indeed, such is the steering’s gearing and lightness that it feels as if you are tackling snaking complexes via telekinesis rather than expending physical effort.

The Mini 1275GT feels like a more grown-up car compared to the frantic Cooper ‘S’

It doesn’t matter that it rides like a runaway ping-pong ball.

The waspish turn-in, bountiful grip and free-flowing torrent of feedback with little roll compensate aplenty.

Getting reacquainted with a Mini is as easy as blowing dust off a favourite book.

Free from the threat of daydreaming drivers in stop-on-a-sixpence moderns – when the MkI’s unassisted brakes will not be pleaded upon to come to the rescue – the Cooper is all about building, maintaining and dancing with speed.

The Mini 1275GT’s cabin is well appointed

It is this that is one of the biggest differences between the 55bhp MkI and Nick Hunter’s wonderfully original 52,000-mile MkII ‘S’.

The black interior, 130mph speedo, chunky sports wheel and column-mounted pod tacho all suggest a more serious drive.

The servo-assisted brakes and greater mid-range muscle deliver on that promise.

Hunter’s car has been modified to include front dampers and larger rear bump-stops – not for this Mini the two-fold Hydrolastic blight of rebound float and pitching under braking.

The Mini 1275GT makes 59bhp from its single-carb A-series unit

Instead, the ‘S’ remains a rapid, blissful way of flinging oneself through the countryside.

Pass 3000rpm, where peak torque is produced, and reach for 6000rpm.

Its greater performance and slightly quicker, heavier steering really up the intensity of its rewards in relation to the 997.

Not so Terry Harrison’s 1972 Mini 1275GT, a car that feels less punchy, less frenetic and more mass-market.

The Mini 1275GT wears tiny 145 SR10 tyres

Gone is the round-nose view ahead, as are the original interior and doors – those thicker vinyl seats, wind-up windows and internal hinges all doing their bit to chomp away at the Coopers’ squash-court roominess.

The three-spoke wheel and three-clock dashboard certainly don’t lack charm – even if it’s more cosmic ’70s than groovy ’60s – but Leyland has done its darnedest to cut costs.

Only the instrument graphics prevent the vinyl interior from being damnably dismissed as a coal-hole.

After the 1275GT, enthusiasts had wait nine years for the next hot Mini: the 1989 Mini ERA Turbo

Over enticing roads, the 1275GT’s relative lack of power and torque, plus higher final drive, combine to make this Mini feel more laid back and less feisty.

As the engine thrums and tappets jig – the tacho is on strike, comrades – the cone-suspended 1275GT just doesn’t have the Coopers’ sharp-toothed cornering edge.

Packing an all-synchro ’box and carrying less hubbub and commotion, this go-faster Mini is a more mature, calmer all-rounder.

The Mini ERA Turbo sports a very 1980s interior

Although Leyland Special Tuning could provide owners with a Sports Performance Kit with enough ginger to overcome its sparkle deficiency, the 1275GT could not replace the ‘S’ in the public affection.

Come 1980, the Clubman would make way for the Mini Metro.

Quick-Mini enthusiasts had to endure nine years of abstinence before Engineering Research and Application Ltd (as ERA had been renamed in the 1950s) provided a car to feed their need.

The famous three-disc badge on the Mini ERA Turbo

Based on a partially built Mini City supplied by Rover and modified by ERA prior to assembly, the Turbo is a quintessentially ’80s interpretation of a Cooper ‘S’ successor.

Bearing a bodykit designed by Dennis Adams of Marcos fame, plus the 94bhp A+ engine from the Metro Turbo, the 30-year-old saloon was punted from 0-60mph in 7.8 secs and on to a claimed 115mph.

Ensuring that the ERA’s handling would remain uncorrupted and Mini-ish, the suspension was modified and lowered, and there were Metro brakes plus 6J x 13 alloy wheels.

This Mini ERA Turbo’s A+ engine has been tweaked

The ERA featured an improved driving position, too, with a Connolly leather-trimmed interior and bespoke dash, wheel and seats to bolster the car’s sense of plush refinement – and, perhaps, to justify a price that trespassed onto hot-hatch territory.

Available through selected Rover dealers, the ERA tapped into Japan’s blossoming Mini romance – an affair that would not only keep the car in production but encourage Rover and John Cooper to resurrect their offspring.

Meetings between Longbridge and Cooper – who had developed a successful dealer-fitted twin-carb conversion for the Mini 1000 – led to the idea of fitting a lead-free, catalysed version of the MG Metro’s single-carb 1275cc A+ into the Mini.

The Mini ERA Turbo’s five-spoke alloy wheels

The development work was undertaken by Rover Special Products, and the reborn Cooper was launched in July 1990 as a ‘Commemorative’ (or ‘RSP’) limited edition of 1000 UK cars, plus a further 650 for Japan.

History would be repeated because these figures were not enough to quench demand, and the Commemorative model was replaced by the slightly de-specified ‘Mainstream’ Cooper, which became a permanent addition to the range.

The most obvious difference between the two is the loss of the John Cooper-signed bonnet stripes, the red leather steering wheel, sunroof and colour co-ordinated wheelarch trims for the 12in wheels.

Mini Coopers blend modern usability with old-school entertainment

Later in 1991, the Cooper lost its SU carb in favour of single-point fuel injection.

In 1996, the Cooper inherited the last of the Mini’s improvements, when the MkVI became the MkVII.

Notables included multi-point fuel injection, a front-mounted radiator, full-width dash, driver’s airbag and optional Tonka-esque 13in ‘Sportpack’ alloys.

Both single-point and multi-point injected Coopers would sire a host of limited-edition variants, before the end for the quick Mini came in 2000.

The Cooper name returned to the Mini line-up in the 1990s

Ricky O’Hara’s featured ERA Turbo is the third prototype – it went to Jack Knight for experimental engine and gearbox testing – and is the earliest-known survivor.

Modified by its previous owner, it is fitted with a high-boost 1293cc MED engine that boasts a charge-cooler, plus steel springs, upgraded brakes, a Jack Knight straight-cut gearbox, a KAD quickshift and limited-slip differential.

Inside, the ERA is as plush as it is ’80s – an impression reinforced by the grey leather trim, which is very ‘M&S slip-on loafer’.

The Mini Cooper’s interior remained resolutely old school

It currently produces 140bhp with 12psi of boost (170bhp is possible with 22psi), which represents a healthy increase over the factory’s 94bhp, and O’Hara advises that it should be driven hard.

Approaching 4000rpm, the ERA’s power delivery has all the subtle progression of Frank Spencer experiencing ‘a spot of bother’ with a bazooka.

Go for extended acceleration on the stiffer throttle and your eyes will widen when a front tyre snaps at a drain cover or a chunky road marking.

It should put you off, but it doesn’t – for by then you are already addicted to boost.

The Rover Cooper S-Pack’s 1275cc engine has a twin-carb set-up and a Janspeed top-end

The ERA is a surround-sound hoot.

Its turn-in is not as pure and true as its lesser-shod brethren, but in isolation the ERA negotiates a convincing truce between the argumentative demands of furious torque and unfussed straight-line acceleration.

On the over-run, the orchestra of shrieking straight-cut gears, sneezing dump-valve and screaming idler gear strikes up a disjointed, scratchy, psychedelic cacophony.

Anything that follows the ERA should be as disappointing as returning to work after a fortnight of sun, sea and shandy, yet Bob Needham’s 1991 RSP ‘S’ Pack is anything but.

The Mini John Cooper LE S Works from 1999 has an airbag

One of 78 conversions carried out by John Cooper Garages for the not-inconsiderable sum of £2900, the 80bhp Rover-supported Janspeed kit included a flowed cylinder head, sports exhaust system, twin HS2 carburettors and high-lift rockers, plus a 3.44:1 final-drive ratio (RSP 3.1:1), a damper/tyre handling pack, and a host of cosmetic flourishes and badges.

Janspeed’s top-end has transformed the A+.

It euphorically zings around the tacho emitting a cheeky, fruity exhaust parp.

Its Metro gearbox proves a revelation – changing positively, lightly and consistently from one ratio to the next without any four-lettered encouragement.

Just 25 Mini John Cooper LE Works cars were converted to ‘S’ spec

The 12in wheels don’t get distracted by surface imperfections, while corners are casually tossed into the past with Cooper ‘S’ zeal – plus the added benefit of less noise and a better ride.

It’s a very resolved blend of ‘S’ capability and 1275GT usability.

Peter Farley’s 1999 car is the 15th of only 25 LEs that were converted into S Pack spec by John Cooper Garages.

The interior and the 6J x 13in wheels are the obvious changes, hinting at the ‘boutique’ direction in which its big-bottomed successor would take the Mini name.

Multi-point fuel injection made its way into the Mini Cooper from 1996

Refinement is this car’s key quality.

The greater torque from the MPI engine allowed the use of a higher 2.76:1 final drive to make it a quieter cruiser – although the deep sports exhaust is far from shy and retiring.

A front-end pedant could moan about the wider wheels having a slightly detrimental effect on this, that and t’other – but the steering is lighter than that of the ERA and I suddenly find myself having daily runabout ideas.

After all, this Mini even has side-impact bars and an airbag.

The Mini John Cooper LE S Works has 6J x 13in wheels that give a purposeful look

A decision has to be made.

In truth, any of these wheeled elixirs would merrily tickle the most jaded of drivers, but with its ‘stop and go’ performance, unadulterated handling, roominess and 1960s décor – glazed with a glimmer of uncouth glee – it is the Cooper ‘S’ that edges it, and blows my bloody doors off.

Damnation! Talk about falling at the final hurdle.

Images: Tony Baker

Thanks to: the Mini Cooper Register; Curborough Sprint Course; Gerard Hughes

This feature was first in our February 2015 magazine; all information was correct at the date of original publication

Factfiles

Morris Mini Cooper MkI

Sold/number built 1961-’64/24,860 (including Austins)
Construction all-steel monocoque with subframes f/r
Engine all-iron, overhead-valve 997cc ‘four’, twin SU HS2 carburettors
Max power 55bhp @ 6000rpm
Max torque 54lb ft @ 3600rpm
Transmission four-speed, three-synchromesh manual, FWD
Suspension independent, at front by unequal-length wishbones rear trailing arms; rubber cone springs, hydraulic telescopic dampers f/r
Steering rack and pinion
Brakes discs/drums
Length 10ft ¼in (3054mm)
Width 4ft 7½in (1410mm)
Height 4ft 5in (1346mm)
Wheelbase 6ft 8in (2032mm)
Weight 1315lb (597kg)
0-60mph 17 secs
Top speed 85mph
Mpg 27-35
Price new £679

Mini Cooper ‘S’ MkII
(where different to MkI Morris Mini Cooper)

Sold/number built 1967-’70/6329 (including Austins)
Engine 1275cc
Max power 75bhp @ 5800rpm
Max torque 80lb ft @ 3000rpm
Transmission all-synchromesh post-Oct ’68
Suspension interconnected Hydrolastic displacers f/r with rear helper coil springs
Brakes discs/drums, with servo
Weight 1435lb (651kg)
0-60mph 11 secs
Top speed 97mph
Mpg 28-34
Price new £719