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Caterham Seven | PH Used Buying Guide

Like having a baby, Seven ownership is life-changing. And, like a baby, you'll want help. Here's a start...

By Tony Middlehurst / Saturday, January 04, 2020

There can't be many PHers of a certain age who haven't entertained the notion of assembling a Caterham 7 kit in their garage. Just about every magazine, website or TV programme that's taken on the job has found that it's not exactly the work of a weekend though, even when you're starting from the Complete Knock Down kit. Caterham says between 80 and 100 hours, which doesn't sound much when you read it on the screen, but if you're only able to spend an hour or two a night with the spanners it can seem like a stretch.

The good news is that you don't have to spend your evenings and weekends putting the 'no profane, no gain' theory to the test while repeatedly turning the Caterham build manual to (you hope) ever more helpful angles and then, when it's all up and together, going through the IVA (previously SVA) testing and registration process. That's because you can buy a new, ready-to-go car from Caterham at prices starting from £27,490 for the now 135hp Ford Sigma 1.6-engined 270 (which started off as a 125hp car). Today you'll pay £28,990 for the 152hp 310 version, while the 180hp Duratec 2.0-engined 360 is £31,490, or £34,490 for the 210hp 420 version.

You could even have £50k's worth of supercharged 310hp 620, but our first bit of Caterham advice would be not to get too wrapped up in the idea of a high-powered Seven just for the hell of it or because you're not sure if your powerfully-built ego will be able to handle the prospect of telling your mates that you've gone for the weediest option. Unless you're planning on haunting the trackday grids on a regular basis, you may find that even the least powerful modern Seven, the aforementioned 270, will be ample for your needs.

The car weighs between 530 and 550kg, ish, allowing the 270 to breeze through the 0-60 in 5.0sec and hit 120mph, plenty in an open car whose in-cabin wind patterns are dictated by a flat slab of glass and your bony elbow poking out of the side. Spindly 4.5J x 14in wheels and a typo-sounding weight of 490kg add up to fun even in the tiny three-cylinder 660cc Suzuki kei-motored 80hp Caterham 160 on sale from 2013 to 2018, when Suzuki stopped making those engines.

Here are the performance stats for all the recent Sevens:

80hp 160: 0-60 6.9sec, top speed 100mph
135hp 270: 0-60 5.0sec, top speed 122mph
180hp 360: 0-60 4.8sec, top speed 130mph
210hp 420: 0-60 4.0sec, top speed 136mph
310hp 620: 0-60 2.8sec, top speed 155mph

All this stuff about new Sevens is by way of an introduction to your third and some might say best Caterham option, which is to scout the PH Classifieds for a used example. Buoyant secondhand prices reflect the timelessness of the driving experience, the relatively low mileages put onto these cars, the simplicity of the design, which knocks on positively to reliability, the lightness of the finished product, which keeps consumable costs surprisingly low, and the whole Caterham 'thing'.

For all these reasons you won't find many Seven bargains about. At the time of writing there was a 2015 Suzuki-engined 160 on PH at £16,900, which is around a thousand quid less than what they were new. A 2017 example of the 160 with 4,000 miles on the clock is only £95 cheaper than the then-new list price.

As we're now in 2020 and we like to think that we're modern round here, we're going to concentrate on the Ford-engined cars that began taking over from the light, powerful but mechanically edgy K Series cars after Rover collapsed in 2005, but which continued to be available in one form or another right up to around 2013.

You should be able to pick up a 2007 Sigma Roadsport with under 20,000 miles for £18,000-£19,000. Roadsport, as the name implies, has been the badge for more everyday road-oriented Sevens since the mid 1990s. The Supersports name was adopted in 2012 to describe a slightly tuned up and stiffened 1.6 Sigma-powered car with a closer-ratio gearbox and a lightened flywheel.

The high-performance CSR of 2005 was touted as the first 'new' Seven in 48 years. Built on the SV platform, it had fully-independent double-wishbone suspension all round with pushrods linking coilover spring-and-damper units. Superlights are more extreme, pared-down models, and you'll occasionally find Tracksports, ex-Academy and LSD'ed SuperSprints for sale.

Whichever Seven you go for, you'll be buying into something more than a lightweight confection of aluminium and composite panels tacked onto a steel spaceframe chassis and shoved up the road by engines designed to propel cars that were twice as heavy. You'll be buying a car that you or just about any garage will be able to work on - and you'll be buying into a legend.

Bodywork & Interior

Both the Roadsport and Supersport Sevens came in two basic chassis sizes, the traditional narrow-bodied Series 3 (S3) and the 110mm wider, 80mm longer and 25kg heavier SV that arrived in 2000 as a £1,000 option for those of a more portly, taller or less snake-hipped aspect. For bigfoot types the SV provided an extra 25mm of vertical space and 55mm of width in the footwell. You could even specify a lowered floor, and that's considered a good option for all but the vertically challenged.

Without the benefit of a side by side comparison, you can spot the difference between the S3 and the SV by counting the hood poppers on the windscreen frame, but someone else will have to come on here to tell you what those numbers are. The SV also had a wider front track and a bigger fuel tank.

Because the body panels are either aluminium or glassfibre (for the nosecone and wings), rust in the accepted sense of the word isn't going to be a problem. However, even aluminium oxidises, and the Seven's aluminium skin is part of the stressed chassis, so don't just leave the bodywork to its own devices in the fond hope that it will look after itself. The powder coating on the mild steel chassis doesn't last for ever either, so keep an eye out for perforations there.

Well-meaning passengers might use the windscreen as a grab point for heaving themselves in, which can cause cracks in the bottom corners of the glass or bends in the frame.

Inside, if you can call it that on a Seven, trim levels on base models can be very austere with little more than rubber floor mats and cloth seats to insulate you from the car's hard points. Owners paying an extra £2,995 for the luxury S pack got carpets (ooh!), a full windscreen and side windows (aah!), a heater (not really all that necessary), a 12V socket (yaroo!), a Momo steering wheel, and leather seats. Removable steering wheels are good for security and for allowing the passage of your big beery tum-tum.

The composite seats you'll see on some Sevens may look a bit punishing, but don't rule a car out just because of that. If your body fits into them they can be surprisingly comfortable even on long trips. This type of seat from a reputable firm like Tillett will cost between £500 and £800 a throw, so even if you don't fancy your chances of getting in or more imporantly out of them, you can always buy the car and eBay the seats for good money.

The Seven's full hood isn't massively loved as it's a bit of a pain to erect and can generate a Turkish bath type atmosphere in summer rain. Many owners prefer to drive with no hood in place, keeping dry-ish when the rain strikes by going quickly enough to divert the watery flow over their heads. Well, that's the theory anyway. If you're on a tour and don't fancy using up most of your luggage space with the full hood, you can get so-called 'half hoods' from firms like Soft Bits, who also do RE-Bag boot bags for extra stowage. These half hoods aren't really meant to stop you getting wet but they do offer handy bonce protection in hot countries.

If the car you're looking at has a roll bar in place, check the height of it. If it's one of the taller FIA bars you might not be able to use the standard hood and sticks.

Engine & Transmission

As noted earlier, for the purposes of this guide we're focusing on Ford Sigma 1.6 and Duratec 2.0 engined cars. You can buy cheaper Ford-powered kit-built Sevens, but the Zetec motor is a little bit heavy and the Pinto is both tall and heavy, raising the car's centre of gravity. The least said about the CVH that was fitted to some Swiss market cars the better.

By contrast, the Yamaha-designed Sigma unit as used in the Focus 1.6 is light, compact and reliable and suits the Seven really well even (or especially) in 135hp form. Timing is by belt with a long 8yr/100,000-mile change schedule. The chain-driven Duratec is equally biddable, and all ancillaries are easily available off the shelf for both engines.

The sporting nature of the Caterham and the extreme cornering forces it can generate mean that regular oil checks and changes are important. Caterham dry sump or Apollo or Pace swirl tank options are worth thinking about if you're going to be giving it large a lot of the time. The Caterham dry sump isn't that well regarded, however. You won't feel much pain on oil change costs as expenses elsewhere are pleasingly low. A complete exhaust system will be under £350 and a new clutch less than £240.

All modern Sevens bar the 420 and 620R (which have Caterham six-speed manual and sequential boxes respectively) have the Focus IB5 5-speed manual gearbox. Like the Sigma engine and the earlier Ford Type 9 box that you'll find on a lot of earlier kit-built cars, this transmission has a good reputation for longevity, although heavy track use will eventually expose the road-car-spec syncromeshes and reverse may become difficult to engage. The differential bearings can go at the 70-80k mile mark too. Don't assume that the six-speed box is more relaxing at speed either because its ratios are very short.

If you're looking at older live-axle cars, try to determine the axle's origin. If it's from a Morris Ital, as many were, half-shafts, hubs and bearings are known to be vulnerable, especially on cars that are regularly trackday'd and/or have reasonably poky motors. Escort axles are likely to last longer.

Earlier on we mentioned the 'luxury' S pack at £2,995. Chucking another £1,000 into Caterham's coffers would liberate the R pack which added a limited slip differential, lightweight flywheel, sports suspension, racing harnesses and an uprated brake master cylinder, plus composite seats and a carbonfibre dash with different instrument design and a shift light. Obviously, used cars with either pack are well worth having. So are any cars without the R pack but with the limited slip diff which Caterham would fit to cars if asked.

Rear lights can fail without you realising it, either as a result of dicky wiring, a broken brakelight switch, or mud gathering on the connectors. If you're not using the car on a regular basis buy a trickle-charger to keep your battery perky.

Suspension & Steering

Semi-independent De Dion rear suspension design combining the differential and suspension functions within a rigid tube was first adopted by Sevens in the 1980s. Relative to live-axle cars, this was quite a comfort boon on bumpy roads, albeit at the expense of a little more roll - although compared to most cars Caterhams don't really roll at all.

Front suspension is by double wishbones, with slightly longer ones on the 360. As mentioned earlier, the 264hp CSR (Cosworth Seven Road & Racing) 2.3 of 2005 had fully independent suspension all round, which robbed the car of a bit of boot space but endowed it with exceptional damping and pliancy that will shock anyone getting into a Caterham for the first time and expecting lots of bounce and bump-steer on B roads.

The Suzuki-engined 160 had a live axle suspended via trailing arms and a Panhard rod. This design added a little unsprung weight but the actual componentry was lighter. Live-axle Sevens shouldn't be ignored by buyers. With decent dampers and a rose joint or two they can ride almost as well as De Dion cars.

It's really worth spending some time and/or money on getting the suspension nicely set up on a Seven because it will play such a huge part in your enjoyment of the car. Replacement front dampers from Caterham are about £150 each. If you're going to be doing a lot of trackdaying, quick steering rack options are very much worth considering.

Wheels, Tyres & Brakes

The extraordinary lightness of a Seven means that even hard-used examples won't kill their owners' wallets. Do 6000 miles in a year (which would be more than average for a Seven) and maybe half a dozen track days and you'll probably find that the tyres and brake pads still have plenty of life left in them.

Even when the consumables are consumed you'll be pleasantly surprised by the cost of replacements. A front set of brake pads will be under £50, as will a pair of front discs. A four-pot caliper 'big-brake' kit will enhance pedal feel and modulation, both of which are useful on the track.

14in classic alloys are standard in S pack cars, with lighter 15in Orcus alloys in R pack cars, which can also come with 13in wheels for pure track work. Good brand 185/60 R14 tyres are as little as £33 each.

Conclusion

So, you're finally going to do it. You're going to release the genie from the bottle and buy a Seven. Which model should you choose?

Earlier on we intimated that even the feeblest Seven would provide more laughs than many other self-professed 'performance cars', but if you have specific duties in mind your selection landscape may change. If you're planning on a lot of track work, the stupidly quick 310hp sprint-ratioed LSD'd 620 is an obvious pick, but the somewhat cheaper six-speed 420R isn't going to be far behind.

If you're planning on staying closer to terrible British roads, the mid-2000s CSR is spookily useable for such a light car. The more recent but less powerful 160 and 270 Sevens will also do a great job, but for a strong and more up to date mix of controllable power and pace allied to very acceptable fast touring comfort, the 2.0-litre 180hp 360 may well be the perfect solution. Its only downside against the 270, if you're being picky, is slightly inferior bump absorption.

There's a load of online stuff you can delve through to build up your pre-purchase Caterham knowledge. Blatchat.com and the Lotus 7 Club are good kicking-off points, although to access the info on the L7C you’ll have to be a member which is not cheap at £49.50. Talking of kicking off, it's a shame that the relationship beween the L7C and Caterham Cars is effectively non-existent. That’s the result of a spat about the use of the word ‘Lotus’ in the name of the club. In Caterham’s defence, all references to Lotus were supposed to have been dropped when CC did the deal with Colin Chapman in the early 1970s. It’s all very boring politics, but there’s nowt boring about the car you’ll end up with when you eventually commit.


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