Gardner Douglas Sports Cars has been standing out in the Cobra crowd for ten years. Not for this company the slavish adherence to a box section ladder frame with yet another 427 body on top. The GD427 benefits from MD Andy Burrows' vision, engineering sense, appreciation and ability.

Besides a unique chassis design and a body shape that is subtly different to those of its rivals, the GD427 additionally offers two mechanical specifications, a build format that allows the chassis and body to be built up separately, the best hardtop in the business and the engineering development benefit of back to back race championship wins. That said, the company is keen to kill the myth that GD means race spec Cobra clones. Instead it would like to stress that the knowledge gained from top flight motorsport contributes much to the dynamic ability of its road cars.

Although the company offers its Euro chassis for Ford components, by far the most popular kit format is Jaguar­based. In addition to kits the company can offer every stage of build up to a brand new, fully built car. The test car is a recently completed, Jaguar­based, factory built car that cost £35,000. It also carries the factory fitted hardtop.

However, most GD cars are amateur built and hit the road in exchange for an investment the right side of £15,000.

Company Profile

Gardner Douglas MD, Andy Burrows, had extensive experience of kit cars before he ever set about the design of the GD427. A much in demand coded welder with a wide experience and knowledge of the structures his skills fused together, he started off with an NG TC which he modified to accommodate a Toyota twin cam engine, fivespeed box and back axle.

From there his appetite for design was whetted and he set about drawing a chassis originally intended to carry a variety of bodies. The result was the backbone spaceframe that distinguishes the GD427 today. The body was a 427 shape supplied through a tieup with local manufacturer RW Kit Cars. The first few cars were sold as RW427s before the partnership was dissolved by mutual consent in order for Andy to develop a far more ambitious car. To that end, he established Gardner Douglas Sports Cars in 1989.

Initially the company operated from purpose built workshops alongside Andy's house but, almost two years ago, the success of the marque prompted a move to much larger premises.

Whilst continuing to develop the GD427, the company's latest project is the GD GT; a two seater luxury GT car based on the GD backbone chassis.

Design and Engineering

The backbone spaceframe chassis fulfils several design aims among which the desire to accept alternative bodies was the one that sealed the backbone spaceframe route.

This design also allowed the frame to be light, which, at 140lbs, it is. As ever, there is a drawback somewhere along the way and that presented itself in respect of less torsional rigidity than a wider frame. To redress the imbalance, the upper and lower main rails of the frame are in 14gauge ERW box section steel with the triangulation in 1" 16 gauge round section tube. On its own the chassis records an impressive torsional stiffness figure of 2750 ft/lbs per degree. The figure is dramatically enhanced when the body is added.

Mechanically, the GD can accept a choice of Jaguar XJ6 or Ford parts. For Jaguar builders, GD recommends Series3 XJ6 parts simply because they are the most up to date but Series2 parts are equally useable.

At the front the GD follows a familiar route in using the XJ6 double wishbones with a modification to the lower one to accept the lower mounting of the adjustable Avo coilspring damper unit. No antiroll bar is fitted. The chassis structure at the front has removable bars to facilitate engine installation and removal. There is also a bolton radiator mounting frame which, together with the composite structure of the body, forms a deformable crumple zone.

At the back the GD differs from its rivals in using a full width Jaguar IRS installation. GD's Andy Burrows cites the reason as: "The wishbone and drive shaft are drop forged parts which are heat treated. Cutting and rewelding them causes a weak spot which we would rather not create". He's right too, but owners of Cobra replicas with narrowed rear suspension need have no fear. As long as the job is done properly with a stepped centre joint that's sleeved, welded at both ends and balanced, there's no way it will fail under the loads exerted by even the most potent Cobra copies.

In truth, the only reason manufacturers shorten the components is to give an authentic offset to the rear wheels. GD has some customers who have shortened their axles to achieve the look but the full width system doesn't preclude fitting wide wheels, while it also allows the car to carry centrelock wires on standard Jaguar tyres for a more period look.

The other unique aspect of the rear suspension is the lack of a trailing arm. Again Andy Burrows explains: "The trailing arm on a Jaguar is not an aid to axle location. All it does is feed forces into the floor which is the strongest point of the monocoque. The needle roller bearings of the lower wishbone mounting are specifically designed to accept power, while the hollow wishbone is a torque tube designed to dissipate the forces fed into it.

To my mind, an additional trailing arm running from the hub to the centre of the chassis merely impedes the free arc of suspension movement." The alternative to Jaguar parts is Ford derived components mounted on GD's own adjustable, double­-wishbone suspension all round. The Ford based frame is referred to as the GD Euro chassis. Its development was prompted by a desire to endow the car with ultimate handling through use of the most modern components. At the same time the availability of allnew parts allowed the construction of a brand new car that has attraction for European customers.

On the engine front the GD is designed to carry a small­ block V8. The Rover 3.5 or 3.9 ­litre is a popular choice in either carburettor or fuel injected form. Most other cars use a 302, 350 or 351 unit from either Ford or Chevrolet. Transmission is the Rover five-­speed for the Rover V8 or a T5 Borg Warner unit for Ford engines and the GM equivalent for the Chevys. An alternative is a T56, sixspeed box for the topspec cars. With the GD race car pumping out a stonking 500bhp, the chassis' ability to handle the power of road going engines is not a question that arises.

The body, too, is unique. Firstly it reflects the halfway house lines of the Mk3 289 coilsprung Cobra. It's subtly beefier than the flatarched 289 but not as pumped up as the big bruiser 427. With its underslung exhaust it has Qcar potential. It can look fairly innocent until the power is summoned.

Constructionally, the body is a semimonocoque design chosen for its ability to supply what the chassis lacks. It's a doubleskinned structure moulded in two halves and then jigbonded together with all internal panels in place. The hollow sections of the sills and scuttle are foam injected to create the massively strong side impact protection the chassis lacks. The floors are in 3/4" marine plywood sandwiched between layers of GRP, and the doors are fitted with sliding steel antiintrusion beams to enhance occupant safety.

The body is fitted to the chassis on fourteen rubber isolation bushes, which are easily released for body removal. The wiring loom is fitted with snap connectors allowing the body loom to be separated from the chassis loom while brake and clutch lines feature aircraft specification joints which can be released and reconnected without the necessity to bleed the system. The body can be removed in about an hour.

At the Wheel

Unique is a term much applied to the GD427 as a result of the long and well directed thought seemingly invested in every aspect of its design. The immediate thing that strikes you looking at this car is the hardtop. Of course we've seen Cobra hardtops before and all followed an identical approach in using a GRP roof along the lines of the soft-­top and a choice of sidescreens.  Produced by after market manufacturers, they have to be persuaded to fit, the fixing system usually scratches the paint and weather sealing is far from perfect. Not so the GD427 hardtop.

This car has a hardtop designed to turn an open, two-seater sports car into a closed GT car offering all the comfort and practicality that comes with it. The upper section of the door is a gullwing that releases to rise on twin gas-rams. When fully raised the door is well away from the head of the average height driver, after which you open the conventional door section and get in, pulling the gullwing down behind you.

Inside the GD427 you sit low. You're down behind the screen looking through it rather than stooping forward trying to see under the top screen rail, as is sometimes the case. The low seating position is achieved in the absence of chassis tubes running underneath the seat­well. The seat runners bolt to the plywood sandwich floor.

The driving position is very comfortable with all the controls well placed. The influence of SVA is readily apparent in the recessed instruments with their bezels flush with the dash and in the twin banks of three rocker switches either side of the ignition. The two toggle switches are for indicators and dip beam but they are located in the SVAexempt area behind the steering wheel. The GD uses the Jaguar column, which is fully collapsible but also carries the two universal joints in the extension linkage. The hardtop offers sliding side glass, a well positioned overtaking mirror that allows clear vision even in the rain, a heated rear window, a stereo CD player mounted in the forward roof above the interior mirror and speakers mounted in the rear threequarter roof panels. It's a clever job and has recently been subjected to an SVA test, which it passed.

The trim is a quality job as you would expect from such a prestige manufacturer and the cockpit amounts to a comfortable, well equipped and businesslike office in which to work.

Performance

Performance in Cobra replicas really amounts to as much as the individual driver wants. The GD race car has regularly achieved speeds in excess of 175mph from its Huddart, 500bhp Chevy engine while first Jaguar, and later Euro chassis parts, have carried it round the bends. However, there's a vast difference between a race car and a road car, while few will fit such a big power engine.

This particular car has a standard Ford 302 supplied by Real Steel. Ford claim a power output of 285bhp for these units but Real Steel say dyno tests regularly reveal a power output between 305 and 310bhp. This one has 305bhp @ 6000rpm with 320ft/lbs torque @ 4500rpm. Drive is via a Borg Warner T5 fivespeed box to a Jaguar 3.07:1 differential.  This car has 15" wheels fitted with Toyo rubber. Jaguarbased cars can go to a 16" job for a better choice of high performance rubber while the Euro chassis, by virtue of the more vertical suspension movement of double wishbones, especially at the back, can go up to a 17" wheel.

On the move, this car feels nothing like a race car. The suspension is soft, seemingly too soft, and endlessly compliant, but it's ever ready and willing to summon some urge. You can cruise along in seeming silence as you let the crystal clear sound cement the argument in favour of a CD but the calm is shattered the moment you press the throttle. With 305bhp on board, the 2420lb GD427 (the Euro chassis car is 110lbs lighter) musters a power to weight ratio of 280bhp per ton, which is a hell of a lot for a road car. That will fire it to a benchmark 60mph well within five seconds, while your knuckles will turn white way before the power tops out.

Handling and Roadholding

In terms of handling and ultimate grip, the GD427 is a car that will never be coaxed towards its limits by anyone other than a very competent driver. This means that it has large safety margins built into the suspension and steering geometry that keep life endlessly exciting for road drivers.

Acceleration and speed are no problem even for the less muscular, Rover powered cars while the car's sheer accomplishment round the bends greatly increases its point-to-point pace.

On a hard charge, the car is supremely stable with no twitchiness creeping up the column despite a speedy two and a half turns between locks. As stated, it feels too soft for a top handler but, come the bends, its performance is pin sharp. The day of our drive provided reasonable weather but the roads were wet, despite which the Toyo tyres seemed well up to staying in touch.

On a fast approach to a bend the alldisc, nonservo braking system is well up to scrubbing off speed due to the car being half the weight of the donor XJ6. It's the same for the Euro chassis car, which reflects the same fraction of the Ford Granada Scorpio's allup weight. Braking is powerful and progressive but, despite the lack of a servo, you don't have to stand on the pedal. There's bags of feel coming through the sole of your shoe and you can detect the approach of a frontend lockup well before it happens. It's also a very responsive pedal that reacts to short steadying stabs as you set the car up.

Turnin is not quite in the kart class but still razor sharp, especially at speed, and you've got to be going bonkers before the front tyres lose interest. On a wet road the grip available was surprisingly high, so on a dry road it'll be unshakeable provided you do things right. Out back the general tendency is to follow the front, but 305bhp will easily break traction if you're a little too early or enthusiastic on the loud pedal. Overall the car is pretty neutral, and that probably reflects the classic handling habit of mild understeer giving way to oversteer only I never felt the understeer.

What I did feel was natural controllability and great balance. The Jaguarbased car carries a slight rear weight bias while the Euro chassis exhibits a perfect 50/50. Not that it makes much difference. This car has been cleverly and sympathetically developed specifically as a road car. It may feel cosseting in a straight line but attacking the bends soon reveals its committed intent through its sharp and precise reactions to driver inputs.

Says Andy Burrows: "Actually, chassis rigidity is far more essential to a road car than it is to a racer. In the latter case you can drive round any shortcomings of the car; on a road you can't. This car is specifically set up to give top line performance with maximum safety".

Following our outing in the latest spec GD427 we can only agree. It's an exciting, fulfilling and rewarding car to drive.

The Everyday GD427

Any kit car can be used on an everyday basis. It's merely a question of what you are prepared to put up with in less than ideal conditions in order to enjoy the car's assets when conditions are right. However, the addition of the new GD hardtop greatly increases the car's everyday credentials. What do you want in an everyday car? You want comfort, equipment, convenience, storage, and reliability. Well, this car's got the lot.

It's very comfortable and completely weather proof. It's warm and dry with good all-round visibility when it's pouring outside and, come the sun, you can pop the gull-­wings off and store them in the boot where they stow over the centrallymounted tank.

Where's the spare? Most Cobra owners carry a tube of tyre sealant for use in the event of a flat. If you've ever used one you'll know what a messy job it is, especially for the poor bloke who has to repair it. GD's answer is a 145x15" spacesaver spare comprising the outer rims of a splitrim wheel bolted to a 1" aluminium centre disc. This stows flat on the boot floor thus providing good luggage space even when the gull­-wings are stowed.

You can fit a week's shopping or touring luggage in there, with oddment storage available in the cabin.

The secret of the car's all-round usability is the hard­top that will add about £1500 plus VAT to the cost of the build. It's a factory fit only as it's a skilled job to ensure it fits without scratching the paint as well as keeping out the draughts, but it's well worth the investment for the yearround Cobra user. The gullwing upper door sections may appear a little odd but they are very simple to use and entry and exit from the car is as easy as with a conventional door.

You want an everyday Cobra replica? The GD427 is it.

Verdict

Quite apart from being a Cobra replica, the GD427 is a first class car that has been thoroughly developed to excel in its performance and handling. As a Cobra replica, there are obviously competitors but, despite the unquestioned quality of the main opposition, none can offer what the GD can. The closest rival is the Dax and while the GD offers one chassis and two mechanical formats, the Dax offers one mechanical base for a choice of chassis. However, one is better than t'other, while both GD formats add up to a great car. Certainly where kitform Cobra replicas are concerned, the Gardner Douglas shares the very top branches of the tree.

Over the years Gardner Douglas has won a reputation for fine engineering and innovative thinking, a reputation its two race championship victories have confirmed. However, it's also fostered the image of an expensive car, which is not true. GD's Andy Burrows maintains that when you've done your homework with the legion of brochure material covering all the top Cobra copies, the GD will work out cheaper. That's always a dodgy statement to make but, certainly, the GD is more than price competitive with its rivals. What is perhaps more important, and the prime reason GD customers tend not to stint on their builds, concerns resale values. These tend to be very favourable, thus confirming the reputation of a fine car.

Project Profile

So, should you decide to build a GD427, what's the bottom line? Well, as ever, it depends entirely on how much work you want to do and how much parts hunting you care to undertake.

The starting point is the backbone spaceframe chassis, which comes for the excellent price of £1,950 plus VAT. In addition to the chassis itself, the price of the Jaguarbased chassis includes the steering rack, steering arms and track-­rod ends, the extension shaft and universal joint, the wishbone damper mountings, radiator frame, the differential mounts, body isolation fitting and a nut and bolt pack.

The body comes for £2165 plus VAT, after which you can source your own parts or return to GD for the finishing items.

If you want to go for a more advanced stage of build, the company can supply a fully rolling chassis less engine and box for £4745 plus VAT or a rolling chassis with body fitted for £7205 plus VAT.

Alternatively if you can handle the mechanical bits but fight shy of trim finishing, the unique aspects of GD427 construction allow you to purchase a fully finished body with seats, trim, electrics, brake pipes, pedals etc all fitted and finished for £5750 plus VAT. You then build up the chassis and drop the body on top.

The prices may initially seem a bit high, but looking through the company's promotional literature and totting up exactly what's included in each package tends to confirm the company claim of price parity with the opposition.

In respect of assistance, there is a GD owners' club under the heading of the Gardner Douglas Register, while many GD owners also belong to the Cobra Replica Club. Both clubs can offer endless technical assistance to builders, while the fact that there will be several owners in your immediate area also bodes well for physical assistance when required. Overall, the Gardner Douglas 427 is a fine car that presents the home constructor with a well designed, easily built, quality Cobra that performs and handles in an exemplary manner. We have been familiar with the company's products throughout the ten years of its existence and during that time they have just got better and better.

We congratulate Andy Burrows and Gardner Douglas Sports cars on what they have achieved. The GD name has become one of the major players in the kit car league and seems perfectly set to achieve much, much more over the next ten years.

SPECIFICATION

GARDNER DOUGLAS 427

Owners' Club:           The Gardner Douglas Register, c/o Paul Jubb, 1 St Mary's Cottages, Grove Road, Windsor, Berks SL4 1JF. Tel:  01753 858875.

Full details are available from:

Gardner Douglas Sports Cars, KCi, Pinfold Lane, Bottesford, Nottingham NG13 0AR    Tel: 01949 843299