Marques and Models
Graham Hull casts a designer’s eye over the Hillman Imp, trying to decide whether it is an embarrassing example of British manufacturing and political ineptitude or perhaps the best rear- engined saloon car ever.
We get a designer’s view on that perennial underdog, the Hillman Imp.
You really couldn’t make it up – four years after Alec Issigonis and Alex Moulton delivered the Mini which convinced everyone that transverse, front- engined, front wheel drive was a game changer, the venerable Rootes Group introduced a small saloon that contrarily employed the opposite layout. It seems incomprehensible that a company building the ultra- conservative Hillmans and Sunbeams of middle England could pursue such a mad course of action, and then also open its new factory 300 miles from their traditional base. But of course, there was method behind the apparent madness.
Conventional wisdom leads you to the 1956 Suez crisis as the pivotal point for UK economy cars. With petrol in short supply, getting maximum mpg was suddenly high on the agenda. This encouraged the unconventional small- engined lightweights of bubble cars and fellow travellers, prompting the Rootes Group to add an economy car to their Minx and Rapier line-up. This is mainly true, but a year earlier Rootes already knew they needed something in the lucrative under 1000cc class that Ford, Austin and Morris were exploiting, so the Imp story really begins in 1955.
The fundamental question to the Imp story is, given the Rootes Group’s experience of conventional front- engined/ rear-wheel drive, why didn’t the designers pursue, say, the 1953 Austin A30 approach? This design and its heirs served Austin well for many years, pretty much achieving
the design brief for the Imp. Some say that left to their own devices the Brits will always try to come up with something original. If that is true, such quests are noble, but not guaranteed to make money. It may be less interesting to finesse existing mousetraps, but successful manufacturers often do just that.
Instead, designers Michael Parkes at just 24 years old and Tim Fry at a mere 20 seemed to have been given carte blanche to create a small family saloon. Parkes’ own brief proposed carrying two adults and two children, returning 60mpg and 60mph, being rear- engined and fun to drive. Granting design engineers this degree of freedom wouldn’t happen today as Engineering, Styling Design, Purchasing, Branding, Production and Marketing would be synchronised with regular Board reviews.
However, it would be wrong to conclude that Parkes and Fry interpreted their brief too liberally. Regarding engine location, you have to remember that across the channel the majority of small cars from VW, Fiat, NSU, Simca and Renault were rear- engined, and so known quantities for engineering and marketing. Rootes executives obviously still regarded rear- engines as modernistic. Also, some argued that the way FWD forced a wheel to do two things (steer and drive) was not ideal. The Imp may have been launched into the teeth of Issigonis’ triumphant Mini tearing up the rule book, but from 1959 it took a little while for the Mini to catch on – and of course Ford famously calculated that each one sold at a loss.
Parkes and Fry’s resulting prototype was a stubby, narrow, rounded, rear- engined, two-box car intended to be powered by a new, horizontally opposed, 600cc air- cooled Villiers twin. Its nickname of the Slug probably explained why, on seeing it, Lord Roots is said to have refused to even sit in something so reminiscent of the more eccentric continental lightweights. Regardless of any dynamic abilities, visually it was a non-starter.
As the 1950s progressed, the petrol situation improved and the Slug morphed into a less controversial shape, able to carry four adults and with a more conventional four- cylinder engine. Now a three-box shape, it was codenamed Project Apex.
Turning now to the location of the factory in which it was to be built, it is impossible to overstate the socio- economic impact of the car industry and decisions of where a company builds its cars, with all the associated investment and employment implications. The UK government has long used the carrot of grants and loans to engineer regional development, greatly influencing vehicle manufacturing – just think of BMC at Bathgate, Ford at Halewood, Standard-Triumph at Speke, Vauxhall at Ellesmere Port and DeLorean at Belfast as examples. But second to none as an example of implacable government manipulation is Rootes at Linwood.
Rootes were well established in the Midlands, but were refused permission in the 1950s to expand adjacent to their Ryton plant. Government development policy coaxed (some would say ‘forced’) Rootes up to Linwood near Glasgow and the Hillman Imp was locked into a 1963 Celtic debut. This site was over the road from a new, governmentencouraged Pressed Steel plant (eventually Rootes Pressings Ltd). By 1962 Rootes had invested £23,000,000 at Linwood to build the Imp, the new plant employing 3000 people and a further 2000 at Pressed Steel. As with most car manufacturing, interior soft trim employed a high percentage of females. There was a capacity to build 3000 cars a week, though ultimately only 440,032 were built in total over 13 years.
Bodyshells were made on one side of the road and transported via a bridge to the assembly plant. The Rootes plant included a diecasting facility for the Imp engine block and transaxle, but these had to go down to Coventry for machining and build completion. Units were then transported back up to Scotland for installation in cars. Completed cars were then carried 100 at a time on a special quarter-mile long British Rail train down to the Midlands.
Apart from somewhat imperfect logistics, the biggest drawback at Linwood was the lack of an experienced labour force. What labour was available had shipyard experience, not automotive. Of course this sort of detail wouldn’t have been an issue with Whitehall mandarins. Despite these problems, the Linwood plant in 1963 was regarded as one of the most advanced in Europe, the paint shop for instance using stateof-the-art automatic spraying techniques.
Let’s look now at the Imp itself in more detail. Like the 1958 Lotus Elite, the Imp
used a Coventry Climax FW (Featherweight) all-aluminium unit that had originally been built to a government specification as a portable pump for fire engines. An overhead camshaft and an ability to run at high revs led to the FWA (Automobile), which attracted the motor racing fraternity from the 1954 Le Mans 24 hour onwards. The Rootes team of Parkes and Fry, realising the potential of this unit for project Apex, asked Coventry Climax to make a FWMA detuned 875cc version giving 39bhp at 5000rpm.
The internals were modified to ensure robustness for road use. Recommended maximum speed in each gear was 20, 34, 52 and 70mph, and it could return a frugal 40-50mpg. Autocar’s May 1963 road test regarded these recommended speeds as conservative, stating that 7000rpm could be safely used. Their best top speed was 83mph, and at a constant 50mph they obtained 50mpg. ( The 1965 998cc Rallye Imp and Rallye Chamois specials produced 70bhp at 6500rpm, giving 93mph.)
For the transmission, a new aluminium lightweight transaxle was commissioned (a combined gearbox and differential) with a baulk-ring all-synchromesh gearbox. All road tests commented on a superb gear change. Driveshafts employed Metalastik Rotoflex inboard couplings, these eliminating sliding splines and cushioning shock loads.
Suspension was by swinging A arms with coil- over- dampers on the front, semi-trailing arms and coil- over dampers on the rear. Brakes were 8in drums all round, with a servo on the Imp Sport and Sunbeam Stiletto. Steering was by unassisted rack and pinion, while wheels were 5.50 x 12in.
As for the body, the monocoque bodyshell construction was typical of late 1950s technology using approximately 250 separate pressings. These needed hundreds of sets of dies, with each pressing (stamping) usually requiring more than one process for cropping and piercings etc. Individual pressings were welded into sub-assemblies, then into one unitary shell. By modern standards this required a high spot weld count and was not conducive to robotics, but it did reduce the number of large, expensive, matched dies which tend to be used today to press complete areas of a car in one hit on very large presses. The fuel tank mounted against the front bulkhead contributed to overall torsional rigidity, while the body panel below the boot lid could be unbolted for engine/ transmission removal.
In the 1960s, Rootes like everyone else was trying to eliminate lead filler on bodyshells. Lead had been used for years to cover panel joints (and sometimes to improve shut gaps), lead solder being melted by welding torch and applied onto a joint, then worked by hand while hot before being disked or filed off. The fumes and dust particles were toxic, and it’s said that high- exposure operatives rarely reached retirement age. Apart from health and safety issues, skilled lead loaders wouldn’t have been available at Linwood, so the Imp was designed with little or no need for filler (although the Hillman Avenger from 1970-1978 built at Ryton did use lead, the lead station being in a special area with craftsmen wearing ‘space-suits’ and breathing through air lines).
The biggest no-lead challenge for Styling Design was how to join the roof to the rear wings. On the Imp this required a visible, separate, body- coloured infill strip on the rear quarter. Today, variations on the Imp solution are still often employed. The trouble is that aesthetically joint strips suggest cost cutting, even if subliminally. An expensive solution is to press all of the side of the car (apart from the front wings) in one; the joint to the roof can then hopefully be less obvious, adjacent to guttering sections on top of the car. Rolls- Royce and Bentley after the Silver Shadow brassbrazed the wide rear quarter joint, which avoided the health hazard but still required expert hands. Lead could occasionally erupt with micro blisters under paint, so the demise of its use was good news for everyone, apart from stylists who continue to struggle with joints no- one wants to see.
Ah yes, the stylists! The Imp exists in that no man’s land of car aesthetics where one could hardly dislike it, but would anyone have its photo on their bedroom wall? Rootes’ in-house Styling/ Designer Bob Saward did a sound job on this little rear- engined package. Some cite the Chevrolet Corvair as generally influential (a charge also levelled at the contemporary NSU Prinz 4), and the Imp’s front end is undeniably Corvair. However the Imp’s heavily undercut, tapering, lower waistline feature adds a dynamic thrust
to what could otherwise be something of a plain Jane and helps the short bonnet neutralise the protruding rear- engined tail, thus neatly avoiding the push-me/pull-you feel of the NSU.
The rather tall cabin gives a deep and generous glasshouse, although in side view the rear glass is too long compared to the front. This is probably the price of slimming the rear quarter panel to avoid a long joint line. Front and rear lamps are conventional, the castellated Americana headlamp eyebrows allowing for twin units on some of the upmarket variants.
The hinging rear glass hatch was novel, giving access to a luggage area which could be supplemented by foldable rear seats. By modern standards the 12in wheels look small and date the car somewhat. The interior was simple with good ergonomics, Singers having walnut veneer elements and cars like the Rallye featuring a rev counter. The facia had a restyle in 1968.
Recognising the Imp’s sporty aspect, Rootes went to the trouble of making a coupé version with a 1.5in lower roof, more raked front and rear screens and slightly curved side glass. The steering column was also lowered. Styled by Ron Wisdom who went on to Rover, Imp devotees regard the Sunbeam Stiletto Coupé with its four headlamps and black vinyl roof as highly desirable.
As for aerodynamics, the Imp was tested in MIRA’s wind tunnel and achieved a Cd figure of 0.385 (0.395 for the Coupé), helped no doubt by the lack of a front air intake. Unsurprisingly for a rear- engined car, key issues were cooling at high speeds and directional stability. The Commer van and Husky estate version were less affected by side gusts.
Talking of handling, with FWD now reigning supreme, there is a tendency in some quarters to regard a rearmounted engine as dated, deluded and dangerous, yet the Imp in standard form handled well, and when modified it was outstanding. The Imp’s engine and transmission weighed 176lb, about half that of a cast iron unit, and it was cantered over to lower the centre of gravity. This reduced the potential for ‘pendulum effect’ of the rear overhang and aided front-to-rear weight distribution. Rootes’ engineers learnt from the VW Beetle’s swing arm rear suspension’s propensity to oversteer, and likewise the notorious Corvair which the Coventry boys predictably crashed. So Imps employed an expensive but effective semi-trailing arm at the rear to avoid oversteer and a simpler ‘wishbone’ A-arm at the front, thus creating a neutral handling car.
Many period photos show Minis, Imps and Ford Anglias all cornering well together on track, so wherever the engine and drive is, cars can be made to handle – although they’ll cock different wheels in the air! Certainly all the media road testers – doubtless braced for rear- engined bad manners – extolled the Imp’s sweet handling. Rear engines also have better traction than FWD. Plus, in 1967 the front wishbone pivot was lowered by ¾in, eliminating positive camber, reducing ride height and helping stability if power was taken off mid-bend. This production tweak reflects how quickly Imps were being cornered, ½in wider wheels being an earlier upgrade.
Unfortunately, due to government and company pressures, the 1963 Imp was launched about 12 months prematurely, leaving frustrated owners to effectively complete basic development. That’s why there were so many modifications that the 1965 Imp became the Mk2. This featured a new water pump, the pneumatic throttle was replaced by a cable and there was a new manual choke. The clutch was uprated (taken from the van), the facia reinforced to stop scuttle shake, plus there were minor inlet and exhaust valve changes and additional sound proofing. This fix list explains why early Imps had a poor reputation – development engineers must have been tearing their hair out as they’d repeatedly logged problems such as water pumps.
As well as different marks, Rootes’ Marketing Department also dusted off several previous names, Singer and Sunbeam in particular having luxury associations. So over time we had the following:
• 1963 – Hillman Imp Basic and De Luxe
• 1964 – Singer Chamois with cosmetic upgrades and the first use of the wider wheel
• 1965 – Imp Mk2 Commer Van with the roof raised 4in and a low compression engine. ( This was considered by the GPO, potentially a very lucrative contract, but they concluded that drivers would have ‘enjoyed’ the performance too much...)
Hillman Husky – an estate based on the van
Super Imp – cosmetic upgrades towards Chamois
Hillman Rallye Imp/ Singer
Rallye Chamois – these were 998cc homologation specials
• 1966 – Sunbeam Imp Sport/ Singer Chamois Sport – twin headlamps, twin carburettors etc.
• 1967 – Sunbeam California Coupé Hillman California Coupé Sunbeam Stiletto Coupé (with sport engine and twin headlamps) Singer Chamois Coupé
• 1968 – Chamois – twin headlamps Chamois Sport – twin headlamps
(Plus in 1968 there was a new dashboard across the range)
Under Chrysler UK ownership from 1967, changes tended towards cost- cutting and the Imp became one of the cheapest cars in the UK. Apart from over 20 factory variants in a production run that lasted until 1976, several sports car manufacturers successfully used the Imp’s engine/ transaxle, including Ginetta, Davrian, Clan, Costin- Nathan – and the Bond 875 three-wheeler. These mainly fibreglass vehicles exploited the 875cc/ 998cc unit with advantage over the much heavier steel saloon, but the Imp’s rear engine mount was attached to a removable steel valance, and this required careful consideration on fibreglass monocoques such as the Clan. Racing sidecars outfits also used it.
If I may add my own personal impressions (as a student I was sponsored by Chrysler UK), the Imp felt dainty to drive, not in a bad way but requiring very little physical effort. The steering was light and accurate, the good brakes didn’t need standing on and the gear change was faultless. The cabin was light and airy with excellent all-round visibility, the engine revved willingly and – like all rearengined cars – tended to leave the noise behind. With such a smooth engine, 875cc never felt like insufficient.
Imps naturally cornered well, but having travelled in several with lowered suspension and wider wheels, I can confirm that they could attack bends with real relish. Despite having owned (and being a fan of) classic Minis, it is hard not to regard the Imp as a generally nicer car, but it’s a fact of automotive history that the Mini is iconic and the Imp never will be. Perhaps in part that’s because the Mini is an up front cheeky chappie and the Imp (despite the name) is like a straight-laced Aunt who could be persuaded to play pub piano.
And yet while the classic Mini became synonymous with motorsport, the Imp had considerable sporting success too. The Competition Department at Coventry run by Des O’ Dell seemed verging on skunk works status, with improvisation often being in evidence. For example, Ford GT40 front-mounted radiators could be seen and Aston Martin silencers on the transverse external set-up for Rallycross, while big bore engines cleverly used Wills rings instead of gaskets. I suspect Rootes never wholeheartedly committed to campaigning the Imp, and certainly not the new American owners, yet an Imp won the 1964 RAC Rally one-litre GT class. A Works 998cc Imp also came first and second in the 1965 Tulip Rally driven by Rosemary Smith and ‘ Tiny’ Lewis. George Bevan’s Imps driven by Bill McGovern won the British Touring Car Championship in 1970, 1971, and 1972, while Fraser Imps with some Works support were very successful in their distinctive blue over white livery with a large white cross on the roof, usually lifting a front wheel on corners. Ray Payne, a Hartwell mechanic, won the 1967 BARC Saloon Car Championship with an 850cc version, beating all the 850cc Minis. Emery and Nathan were other effective tuners of Imps.
Despite the somewhat low key projection of competition success, the Imp’s highest profile was quite late in its life. Rallycross, ‘invented’ in 1967, became very popular on TV into the 1970s, and
ex- Fraser driver Peter Harper’s heroic yumping exploits using 1140cc and over 100bhp made a dramatic finale to the little Imp’s saga as he took on and often beat the Ford Escorts and Minis. Success in this tough sport finally laid the Imp’s wallflower image to rest.
In conclusion, the Imp was a good car that had the odds stacked against it from day one. The old adage that it doesn’t pay to pioneer isn’t really applicable here as the Imp followed numerous other rear- engined designs. Parkes and Fry finessed away this layout’s downsides and created arguably the best rear- engined saloon ever. However, Rootes had no experience of small cars, rear- engines were on the way out as the Imp was launched, and in 1959 the Mini heralded the transverse-front engine/ FWD revolution and became the darling of the in- crowd in a way the Imp never was.
Add to this a government that coerced Rootes to build a new factory in Scotland in an area that lacked automotiveskilled local labour, engine components which had to travel up and down the country several times, initial underdevelopment undermining public confidence even when everything was fixed, a sporty prowess that was never convincingly promoted and new American owners who understood cars like the Hillman Avenger but not the Imp and you get an insurmountable list of odds. The Imp wasn’t a failure, but it never had the success it deserved. The zeitgeist was with Issigonis and Moulton rather than Parkes and Fry, but Imps should be cherished and appreciated as more than just a curio overshadowed by the Mini.