Monday 12th March 2007


CATERHAM 7 ROADSPORT

Can the new Ford-engined Seven still cut it, or will you pine for the K-Series? James Mills reports.

Caterham 7 Roadsport
Caterham 7 Roadsport

Itís doubtful that Colin Chapman could have envisaged such a prolonged shelf life for the Lotus Seven, his greatest gift to petrolheads.

But here we are, shortly to celebrate 50 years of the car which refreshes driversí parts other cars canít reach. And just like Chapmanís first Lotus Seven to fire to life, the latest Jubilee spin-off from Caterhamís Dartford factory features Ford power beneath its flyweight, louvred aluminium bonnet.

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New engine

It goes without saying that this is a big deal. As the bread and butter offering of the family, the Ford Sigma engine is trading places with that venerable stalwart of the Sevenís history, the Rover K-Series.

No need to spell out why that is. But why Fordís 1.6-litre Sigma to take its place? Because itís light, modern, has the delivery characteristics to suit the Seven and is clean Ė crucial if Caterham is to meet current EU4 emissions regulations Ė and comes with the R&D muscle of Ford, which will develop the powerplant further to satisfy 2009ís EU5 legislation.

In an age of nanny-state legislation governing the publicís consumption of cars, without Fordís assistance Caterhamís future would be none too bright. And the world without Caterham would be very dull indeed.

The 1,595cc unit is an all-alloy lump with a cross flow, 16-valve cylinder head and twin overhead camshafts. With a higher compression ratio than the K-Series, and Caterhamís own tweaks Ė modified inlet cam timing, Caterham throttle body, engine management system and exhaust - your right foot is treated to 125bhp at 6,100rpm and 120lb-ft at 5,350rpm.

That may not sound a great deal but as any seasoned Seven driver will delight in explaining that, in a car weighing 550Kg (in Roadsport 125 trim), it equates to 227bhp per tonne and 0-60mph in just 5.9 seconds.

Move up the scale to the Roadsport 150 and thereís 150bhp at 6,900rpm but a slightly disappointing 120lb-ft at 5,600rpm. which means 270bhp per tonne and 5.0 seconds to 60mph. Do the right thing and tick the Superlight box on the order form and with 300bhp per tonne youíre talking 0-60mph in 4.7 seconds.

Torque about change

Torque is claimed to be the biggest single improvement over the K-Series, and it has to be said the 1.6-litre engine is flexible, pulling cleanly from 1,000rpm in fifth, but is equally happy hunting out the red line.

And when you do get it wound up thereís all the noise, performance and excitement you could reasonably expect from the baby of the range. At times I canít help feeling it doesnít have the crisp sweet-revving character of the ĎKí, but nonetheless itís a great starting point for any Caterham virgin. Especially if all the customer cars can boast a gearshift as light and smooth as our test carís five-speeder.

Shoe-horning the Sigma engine into the Sevenís chassis was no simple matter, however. It didnít fit. At the same time as the engine programme, the new management wanted to further refine and improve the chassisí spaceframe design, which resulted in an end to the firmís relationship with Arch motors Ė whose enginers bronze welded each chassis by hand Ė and an increased commitment with Caged (now Steel Fabrications Ltd) which designed and constructed all the Sevenís roll bars and race cages.

The company talks proudly of CAD modelling, FEA finite element analysis, computer controlled tube and sheet laser cutters and robotic welding cells. So the rise of the machines even touches Caterham. Whatever next -- snow in the Sahara? The question is, what does it have to show for it on the road?

On the road

I have to say, the spaceframe chassis feels a lot stiffer than the couple of Sevens Iíve run in the past. Caterham claims an increase of 12 per cent, but the impression on your backside and fingertips is far greater. The trademark flexing and creaking of the chassis is less noticeable. Which is good news, as the suspension geometry can work as it was intended to, keeping the wheels in contact with terra firma.

Driving any Caterham is usually a life-affirming experience. And Iím glad to say thatís still very much the case in the new baby of the range. There may not be a glut of power, but if you havenít driven one in a while thereís still a whole new world of sensory stimulation that comes as a sharp wake-up call.

The test carís Avon ZV3 tyres wouldnít be my first choice, but thereís a lot of fun to be had trying to maintain momentum once up to speed. The DeDion chassisí natural balance is nicely neutral. Push beyond that into understeer and you can play around with the throttle, coaxing it into gentle lift-off oversteer and then a whiff of power oversteer if you gas it again in tighter second and third gear bends. And the beauty is, with the touchy-feely tactile feedback Ė through the ever-wondrous steering and seat of the pants - you trust it intimately.

Criticisms? The brakes showed an unnerving willingness to lock up at the front on our car in the wet, but thatís easily fine tuned to taste. And the four-point harness really should be five, as it slips up your torso no matter how tightly you fasten the lap strap.

Meanwhile, the hood remains as quaint as ever. (Donít slow down and you wonít get wet.)

Driveability

It goes without saying that you shouldnít approach the Roadsport 125 expecting 100mph-plus thrills, or the ability to hold court at track days.† And it also goes without saying that not everyone craves the full-blown, mind-numbing performance of top-end versions.

As a starting point, then, the Roadsport 125 does all you can realistically ask of it. The Sigmaís day to day drivability is excellent, top-end performance is stirring enough and the Sevenís chassis is better than ever. And as a pointer of what to expect, it should have Caterham fans excited about the Sevenís future. Roll on the R300...