The Caterham story is one of continual development to find a better mousetrap, a fourdecade process of honing Colin Chapman’s brilliant original design, which, lest we forget, is almost 60 years old. Since 1973, when Graham Nearn’s Caterham Cars took over the rights and manufacture of the flyweight sportster, it’s grown more power, better engines and more sophistication in both suspension and powertrains.
The car’s basic shape has remained unchanged, and is based upon the Series 3 Seven. Above left: marque founder Graham Nearn (in the grey suit) when the Vauxhall engine-supply deal was announced.
Though Caterham completed 42 of the heavier Series 4s, Nearn concentrated on the classic Seven design, the S3: a simple spaceframe chassis clothed in aluminium and glassfibre. The rear suspension is by A-frame and two trailing arms with coilovers – exactly what we saw on the Lotus Cortina – supporting a Ford axle. The first cars had Standard axles, but Dagenham’s light and simple English unit was cheap and came with a variety of final-drive ratios. Front suspension used Triumph Herald/Spitfire uprights and Chapman’s own wishbones, with the anti-roll bar as part of the top member.
At the time of the S3, the power unit was Ford, too, the Crossflow motor producing 84bhp in GTform with a twin-choke carburettor, though Twin Weber DCOEs were never far away. Sevens had started with sidevalve Ford power. That was followed by the 948cc A-series unit as it became available, then Ford’s new four-cylinder engine in capacities of 1340cc and 1498cc, before the head redesign put the intake and exhaust on opposite sides. This Kent engine also forms the bottom half of the Lotus-Ford Twin Cam, which powered, amongst many others, the Elan.
The 1978 Twin Cam here is a Caterham, but in effect it’s a continuation Seven S3, and still wears the Lotus steering wheel. Driving this after the newer cars is a striking step back through the looking-glass. All of the inherent Seven qualities are there – the poised, adjustable chassis, the at-oneness with nature that means you can smell freshly mown grass – but it feels very vintage with its spindly, cranked gearlever and large steering wheel. The cockpit is far more spartan and partly unfinished, with exposed boltheads and sharp edges. The lowerratio steering, however, is as light and fluid as them all, while the clamshell wings accentuate any impression of body roll.
The Twin Cam’s power delivery is as ornery as ever, spitting and banging if you displease it, but with that familiar ‘crobby’ sound off tickover and strong torque delivery past 5000rpm. Maximum power is 126bhp at 6500rpm in this big-valve form. Elan owners will recognise it because it’s the same engine. Pushing 526kg, it’ll do 0-60 in 6.2 secs, the same as the K-series Roadsports but with more drama.
Cherry-picking power units had been a feature of the Seven since it was born. When Ford discontinued the Kent – last fitted to a UK car in 1976 – it caused something of a crisis because that also meant the end of the Twin Cam and Cosworth BDR, of which Caterham had bought 500 over the years. The final pushrod engines came from South Africa, as fitted to Mk2 Escorts – and as in the Seven Classic that the C&SC crew built in 1995 and ran for a year – but eventually Caterham was forced to seek an alternative power unit.
At first, it turned to Vauxhall’s gutsy 2-litre as an alternative for the high-power cars, but Rover had been developing a sophisticated and lightweight new twin-cam ‘four’. It first appeared in the 214 in 1988, and by ’91 the K-series had been adopted for the Seven. Andy Noble, head of sales and marketing at the time, says: “A brilliant engine – innovative, light, powerful (at the time) and commercially viable. It was built in England and Powertrain was very supportive in both engineering and marketing.”
Jez Coates, who joined the company in 1983 and was technical director from 1987-2006, adds: “It came out of a chance remark with an old colleague from my truck days at Leyland, who was by then at Rover, and it turned out to be the K-series. Rover [Powertrain] was incredibly supportive, appointing a liaison engineer to help us, advised us on the sump, and even ran engines on test beds in our configuration, because it hadn’t been mounted longitudinally before.
“We waited for the multi-point engine because it was easier to package – with singlepoint injection something would have stuck through the bonnet and we didn’t want a bulge. We launched on the same day that the engine came out in a Rover Group car – the Metro GTA – which shows how far behind us Rover was. The press criticised the first cars, which were 1400s, saying they lacked torque. That led directly to us developing our own close-ratio six-speed gearbox, which, at 29kg, was 6kg lighter than the Ford Type 9 five-speed that we were using. But as larger capacities became available, we adopted them, ending up with the VVC. That gave us a Euro emissions-legal 160bhp.”
The regular 1.6 K-series makes a nice, reliable 120bhp – similar to a Supersprint 1700cc Crossflow on twin Webers – and it likes to rev, with maximum power at 6000rpm, 750rpm under the redline. Driving the yellow car that Stuart Wylie brought along reminds you just what a sweet engine this is, and so well suited to the Seven. The chassis feels more solid than the older car, the ride chunkier and the wheel smaller – though the steering is still light, even with a quicker ratio than the Twin Cam. Caterham started making its own racks in the mid-1990s and the 8% faster option has become the standard fitment. On more modern Yokohama rubber – but of the same size as the 185/60NCTs on the Twin Cam – this is less squirmy, and the cycle wings bobbing up and down give a better impression of what the front wheels are doing. A middling K-series Seven like this is in the sweet spot, weighs 550kg, has a top speed of 112mph and accelerates to 60mph in 6.2 secs.
But if you wanted big power – and gollops of torque – there ain’t no substitute for cubes. In the late 1980s, the hot power unit, replacing the twin-cam BDR, was the Vauxhall ‘red-top’, beloved of rally boys who still stuff them into Mk2 Escorts today. As Trevor Griffiths, who is here with his JPE-spec car – the last HPC – says: “When it was built, it was giving 240bhp, and it still amazes me every time I drive it.”
And he’s right. Even at 25mph, it feels brutal, especially with the plate-type LSD clattering away behind you. The numbers are 3.5 secs to 60mph and on to 145mph; in practice, it just keeps pulling and pulling in every gear towards the 7750rpm redline. There’s immense grip from the sticky Toyos, this time 205/60s on 7in rims at the rear. The steering is chunky feeling, and it needs its big vented discs up front, with Caterham’s own calipers. It’s not quite the heaviest of our quartet, at about 540kg, but feels it.
Jez Coates: “The Vauxhall happened for the same reason as the K-series – the pushrod Ford was dying and with it the BDR, though Formula Ford prolonged its life until Ford realised that it didn’t want to be promoting an engine that it last fitted to a road car 10 years before. The Vauxhall was a nice, compact engine and packaged well, with the intake on the right, which is more comfortable for right-hand-drive markets, though we used carburettors rather than injection.
And it led directly to our first race series.” By the time the K-series and the Vauxhall came along, interiors had become more plush, with a long-cockpit option and even a wider variant, the SV. There were proper bucket seats instead of a plywood back and push-fit cushions, and in 1996 the handbrake moved from under the dash to the transmission tunnel. That required extra tubing in the chassis, one of the ongoing changes that made the Seven 80% torsionally stiffer during Coates’ tenure.
The front suspension had gained a proper top wishbone and separate anti-roll bar, but the biggest single change came with the adoption of de Dion rear suspension. This was as much about the lack of live rear axles as sophistication – there had been a switch to Marina van axles after the Ford units ran out – and typically it used existing parts, such as the Sierra differential.
Coates: “My first job was deciding the length of the driveshafts. When I joined the company the name of the game was keeping the car in production, and this was the first time that Caterham had engineered something itself.
Ameeting about it was convened in the local pub and, in the end, the de Dion was a no-brainer: it kept the rear wheels linked and parallel to each other with a great big tube. Independent is fraught with a lot more problems, though I did have the ambition to do a fully independent car and eventually got my way with the CSR in 2004. Also, there was a precedent because there had been de Dion Sevens in the past and that was a way of keeping the Lotus tradition.”
With the same layout of A-frame and twin trailing links – plus similar geometry – de Dion Sevens don’t handle too differently to a live-axle car on a smooth track. The difference is most apparent on a bumpy road, where the ride is smoother, traction better and the car feels better planted – a great confidence booster. Almost all Caterhams have been built this way since 1984. De Dion cars have twice the boot space because there’s no need to accommodate the travel of the live axle, and A-frame bushes last longer because they don’t get contaminated by oil.
The collapse of Rover in 2005 meant another engine change – a quick alternative to the K-series was needed, and by this time Ford had caught up with its Sigma range. Noble says: “Ford was the best option and the motor fitted – a lot of modern engines are just too tall!”
Caterham’s quickest offering in 2016 is the 310bhp 620S, but adding power to a Seven is an exercise in diminishing returns because of the relatively poor aerodynamics. Now the wheel has turned full circle with the 160 – as with all the current cars, the clue’s in the title, that being its power-to-weight ratio. This uses a 660cc Suzuki ‘kei-car’ turbo triple, has reverted to a live axle (from a Jimny) and offers similar power to the classic single-carb pushrod Ford. The base 160 costs £16,995 but the featured example has the S pack, meaning carpets, leather seats and full weather gear, plus a Moto-Lita wheel.
Fire it up and it sounds much mightier than a tiddler, even with the turbocharger damping the noise. At tickover, it’s as imperceptible as a coffee percolator, though it vibrates a little. As you take off, the sudden slug of torque at 3500rpm – along with various turbo whistlings and blowings as you quickly work through the gears – is a concept that’s initially a little odd in a Seven. You soon revel in it, though.
With just 79lb ft and weighing less than 480kg, it doesn’t need fat rubber. On narrow 155-section tyres it’s a joy, akin to early Sevens, and it moves around even more than the Twin Cam, though with so little weight it doesn’t so much corner as change direction. It is hilariously adjustable – you can prod the tail out on the power if you use second gear, but then you keep running into the rev limiter at 8000rpm.
There’s quite a large gap between third and fourth, most noticeable when changing down, and the fifth-fourth shift is a little imprecise in this Suzuki ’box (most have MX-5 five-speeds). At 14mph per 1000rpm in top, it is ridiculously low geared, which makes it fabulous fun in a ‘pursued by an angry swarm of bees’ sort of way – 75mph comes up at about 6000rpm, with 2000rpm to go, though 70mph is about your lot without sidescreens. Top end is just 100mph but that doesn’t matter. Up to 90mph is a Seven’s best envelope. Its sparkling acceleration at road-legal speeds (6.5 secs to 60mph) means that in practice you’re ahead of everything away from traffic lights and roundabouts, and there’s enough squirt for safe overtaking.
It really isn’t that quick – it’ll just stay with an Audi A4 TDI up to about 70mph, for example – but that’s not the point. Less is more, and the 160 is a little gem. It’s just great fun, as nature and God (Chapman) intended. Casual observers love it, too, and appreciate its delicate stance on narrow steels. Who needs more? I can’t wait for a 1-litre turbodiesel version.
How long can the Seven continue before it’s legislated out of existence, like the Citroën 2CV and Land-Rover? Simon Lambert, who’s the current chief motorsport and technical officer at Caterham, says: “At the moment, we’ve no indication that it’ll ever be taken off the road, as long as we continue to comply with emissions regulations. There’s not much car to develop, so it’s not so much about that as fine-tuning – if you’re not careful you can end up with a heavier car; see what happened to the Elise.
“People have been saying ‘five to 10 years’ for as long as I can remember, but I’ve been with the company for 16 years and was a supplier for 10 before that. In fact, we might even be able to start exporting to the US soon thanks to legislation changes under the 25-year rule.”
With production at around 500 cars a year and about 16,000 Caterham Sevens built to date, it’s often said that if you park 100 together no two will be alike – even our foursome confirms that. With the 160, Caterham has shown that it can pull new rabbits out of the hat, so there’s life in Chapman’s remarkable concept yet. Truth is, you’d be overjoyed to own any of them.
Thanks to Stuart Wylie of Woodcote Sports Cars: www.woodcotesportscars.com; Paul Clugston of UK Sports Cars: www.uksportscars.com; Richard Denham of RDD Automotive; Jez Coates; Caterham Cars: www.caterhamcars.com; Trevor Griffiths.
From top: tiny turbo twincam ‘triple’ in 160 adds lightness and gives good acceleration; even basic cars now have heated ’screen; with Jimny rear axle and inset steels it’s narrower than the others; new branding from 2014; top-mounted intercooler.
‘THE 160 IS HILARIOUSLY ADJUSTABLE – YOU CAN EASILY PROD THE TAIL OUT IN SECOND GEAR’
‘THE JPE KEEPS PULLING AND PULLING IN EVERY GEAR TOWARDS THE 7750RPM REDLINE’
From right: mighty red-top engine – this one is on injection, though most factory cars used carbs; 16-valve badge; brutal acceleration means that this car runs shift lights; vented discs are vital, plus fatter rubber on rear; widetrack front suspension.
‘THE K-SERIES WAS A BRILLIANT ENGINE – INNOVATIVE, LIGHT AND POWERFUL’
From left: light K-series was a perfect match for Seven; wreath badge; note position of handbrake – it had moved to the tunnel from beneath dash when de Dion rear was adopted; Minilite-style wheels; anti-roll bar now separate from the top wishbone.
From top: clamshell wings accentuate body roll – anti-roll bar forms part of the top wishbone on early cars; rather more yellow on this TC than when it left the factory, and the dash is custom; GKN alloy wheels; big-valve Twin Cam on twin Weber carbs.
‘DRIVING THE TWIN CAM IS A STRIKING STEP BACK THROUGH THE LOOKING GLASS’
Plenty of alternative power units have been tried in Sevens, from a rotary to a 500bhp 2.4-litre V8 based on two Kawasaki Ninja engines. Motorcycle power makes sense because of lightness; the relative lack of torque doesn’t matter so much in a lightweight. John Bedford’s car is one of 24 made (with Caterham’s blessing) by James Whiting. It’s powered by a Honda CBR900RR Fireblade engine – and anyone who’s ridden superbikes will know that the quoted power of 127bhp at 10,000rpm is conservative. It retains the six-speed ’bike gearbox and drives through a forward/ reverse ’box to the live axle via propshafts.
“The engine and transmission weigh only 66kg,” says Bedford, “so we reckon it’s just shy of 400kg in total. In such a light car it’s not peaky – it’s less temperamental than the VHPD K-series in my fiancée’s Elise. It’s doing 9000rpm at 100mph, but there’s still good acceleration, and you shift without the clutch. I’ve been timed at 117mph at Snetterton and it would probably do 120. It’s back to basics, very much in keeping with Chapman’s original concept.”
What to look for
Stuart Wylie has been trading in Caterhams since 1988, and reckons that around 1000 have passed through his hands. He says: “I look for general condition and mileage. With the body being aluminium you can’t hide damage, but have a look at the chassis for corrosion because the tubes can lose their powder-coating, resulting in rust. “On cars from the mid-1990s, there was a problem about halfway along the side as the body line changes, where a reaction between the ally skin and the steel of the chassis could result in corrosion. If you scratch the surface, there would be white powder under the paint, so check carefully for bubbles. The windscreen is heated and expensive at £350-400, so have a good look for any cracks or chips.
“Listen to the engine for any odd noises. On a test drive, you might think that the diff is on the way out – it’s just how they are, and you feel more clunks in a live-axle car – but if they’re too noisy it can mean a differential rebuild.
“The A-frame bushes deteriorate faster on live-axle cars – grab the roll bar and pull hard from side to side to see if there’s any movement in the axle – but they are cheap and simple to change.
“I’ve never known a head gasket to go on a K-series in a Caterham, but if you are buying an R500 it must have good service history because the engine is fragile; they can need a refresh after 5000 miles. The Type 9 fitted to most cars is bulletproof but the six-speed Caterham ’box can give problems.”
Expect to pay £12,000 upwards for a pushrod liveaxle car or leggy K-series. Lower-mileage K-series will be £15k-plus, while £20k gets you into a Vauxhall/Sigma/ Duratec. Twin Cams and Cosworths start here.