The Radical Approach
Sir With regard to the views apropos motor racing and the environment expressed by Mike…
Good hard fun
When we arrived at the Thames Ditton base of AC Cars Ltd, we were surprised to find a virtually empty factory. It soon transpired that the company was in the middle of transferring to a smaller building on the same site, as Sales Manager Keith Judd explained. With the demise of the three-wheeled invalid carriage which formed an important manufacturing base for the company during the Sixties, the emphasis of the Group has shifted away from cars to the manufacture of lorry trailers at a separate plant. Nevertheless, AC’s 73 year tradition of building sports cars, including the legendary Cobra, is being maintained with one of the few British mid-engined sports cars in current production, the 3000ME.
The body of the 3000ME is virtually that of the Diablo, first seen in 1973, but the car underneath is entirely different, and given that it involved a small company developing chassis, suspension, and a special gearbox, as well as making jigs and moulds and obtaining Type Approval, the five years which elapsed before the first sales in 1979 becomes understandable.
The quality of the engineering is obvious when one sees a car being assembled. A Ford 3-litre V6 sits transversely in a steel perimeter chassis of very neat design whose all wishbone suspension is fabricated by AC. The exhaust is outrigged directly from the engine to avoid flexing, and the 14 gallon fuel tank is tucked tidily between engine and cabin. Cooling air for the front-mounted radiator is vented through a grille above the nose, leaving room for a storage well between the front wheels which accommodates the spare wheel and tools.
Why the Essex 3-litre rather than the Cologne 2.8? Essentially because AC’s unique tailor-made five-speed gearbox will not fit any other block. We will return to the engine later, but it is worth looking at the ‘box, because it is beautifully, even extravagantly, designed. Using Hewland gears and driven by a triplex chain, it runs on needle-roller bearings and has centre bearings on the shafts. Lubrication is ensured by feeding oil through the hollow mainshaft. Even the final drive pinion is machined up by AC, and the result is a very strong box which is capable of very fast changes.
Clothing all this is a GRP body of flawless quality in which the junction between the two main mouldings is frankly impossible to detect, even before painting. A steel frame ensures the doors shut with a satisfying clunk: in fact all panels are assembled and adjusted for fit before being separated for painting. And there are a lot of opening and closing panels — eight in total including the pop-up lights.
Production has settled down to one a week now that the cars are sold direct from the factory (list price £12,658) but at the moment it is only a question of assembly, as AC have built up a healthy stock of chassis, bodies, and components which is drawn on as required. Delivery time runs at six to eight months, and being such a small operation allows for the customer’s own specification to be incorporated.
After exploring the factory we climbed into the glossy white demonstrator for an acclimatisation run. The first lesson to learn is that it requires a rump-first entry technique because of the high sill, but once installed the position feels natural, helped by fully adjustable seats and steering column, and pedal-pads which screw in and out. The left hand falls easily onto the gearlever, although the handbrake is too far back, and the speedometer and rev counter are perfectly visible within the thick-rimmed leather wheel. Other instruments, however, require the neck to be craned. Visibility is superb, barring only the small rear three-quarter panel, and while the bonnet drops out of sight, the short overhang offers no manoeuvring problems.
Unusually for a car with a remote change, the gearlever operates in a gate, which demonstrates AC’s confidence in their assembly tolerances, and demands similar accuracy from the driver. Even upward changes must be carefully judged, and the ‘box is not forgiving — bungle it and it is back to square one. Driven hard it works well, but it demands a lot of concentration.
With the engine so close to the occupants’ heads, there is a fair but not unpleasant amount of noise—it is just a shame that it is not ora more exciting variety. The Essex V6 is a slogger, and its reluctance to reach high revs means that the car feels slower than it is (AC claim 8.5s from 0-60 mph).
Handling is of course the raison d’être of the mid-engined car, and there is no doubt that the AC with its 205/60 Pirelli tyres offers a very high level of grip. It turns in at a twitch of the wheel, and at any reasonable road speed corners virtually flat with the merest trace of understeer. The front wheels are sensitive to the smallest corrections by the driver, which is good, but also noisily impart the shock of every bump through the steering wheel. This characteristic amplifies the effect of the ride, which can only be called hard on country roads, although it absorbs single bumps smoothly. One should never be silly enough to back off completely in a fast corner in any car, but in the AC there is a curious wriggle if the throttle is lifted just to trim the speed. The rear tyres stay confidently attached to the tarmac, but the body appears to move just slightly in relation to them.
For a mid-engined car, the AC is a model of practicality. The forward storage compartment, unencumbered by the radiator, not only swallows the spare wheel (and remember that is of seven inches width) and the inevitable automobile oddments, but also takes the large detachable roof-panel in its leathercloth storage-bag which is a standard fitment. This leaves the 12 cu ft boot which occupies the tail free of clutter and able to cope with considerably more than the expected “weekend” luggage. The boot has a handle, but the front compartment and engine cover are released from inside the cabin by cable. All covers are self-supporting by hydraulic strut, and engine access is surprisingly good.
Interior appointments are sober, comfortable and, in common with everything about the car, beautifully finished. Leather seats are standard, and the small glove-box and rear bulkhead pocket will not about cope with everyday odds and ends.
Having experienced faint disappointment about the out-and-out performance of the the unobtrusiveness of the standard model, it was interesting to be allowed the opportunity to try a turbocharged version. Robin Rew, whose premises areas Silverstone Circuit, has been converting the Ford V6 for several years, first in the Reliant Scimitar and latterly in the AC, and has been using his own 3000ME in hill-climbs as well as developing a lightweight car for Reg Hill to compete with in the Hillclimb Championship. He offers a standard package, axon the car we tried, but will install any combination of boost and camshaft that a customer requests.
“Our” car was one which was newly converted, and its owner, Sirnon Carlton, very kindly allowed us to try it before he had driven it himself in its faster guise. Like most of Rew’s conversions, this one ran at 7 lb boost with the combustion chambers machined to lower the compression ratio to 8:1, although Cosworth pistons are available with a 7.2:1 ratio for higher boost engines. The system has been carefully developed; for instance, there are no gaskets in the exhaust system. Instead, metal sleeves machined into head and manifold form a seal within each tract. Similarly, the heads are grooved to take a copper wire which bites into the flame rings, improving the cylinder seal.
An IMI turbo blows through the standard twin-choke carburetter, which is repositioned to minimise fuel surge via a small circular airbus which evens the flow to each choke. Two valves protect the system, the wastegate diverting exhaust gas to limit boost, and a dump valve releasing intake pressure when the throttle is closed to maintain turbo speed. This also operates in the event of a backfire, or of the wastegate socking. On the test car, this operated with an annoying chatter every time the throttle was released, but as Rew demonstrated on his own car, a simple change of spring can alter this to a loud sigh.
One of Rew’s modifications is to the geometry of the rear suspension which results in a little pre-loading being applied to the tyres before the car turns in to a bend. It is perhaps a matter of personal opinion as to whether this is preferable, but we found that the car felt more settled entering a bend, and happier about throttle alterations halfway round.
But of course the instantly obvious difference is in the performance. The boost starts to build below 2,000 rpm, and by 3,000 the car is rocketing forward, and it is time to try for the next gear because the rev limit is only 5.500 rpm. The engine is ideal for this form of tuning because of its low speed torque, and this helps to smooth out overall performance, but it is a pity there is not a little more top end. Nevertheless, the car is very rapid. It can be pushed into corners at very high entry speeds which saves the leg muscles a lot of effort operating the heavy but effective brakes. In addition, the turbo car seemed very nervous under braking, unit was good not to have to brake every time. Perhaps this had something to do with the mixture of tyres it sported — Dunlop 04 on the front, Pirelli P6 on the rear.
It is undoubtedly quick (Rew estimates it has a little over 200 bhp, compared to the standard 138 bhp) and certainly practical. It is tremendous fun to drive, but rather tiring, what with the gearchange, hard ride and sensitive steering. If you are prepared .to work hard you will enjoy an AC foe its sprinting ability and for the attention it generates and Rew’s package at £1,180 (until December 31 — £2,000 thereafter) is worthwhile investment. But if you are lazy or easily bruised… — G.C.
Sir With regard to the views apropos motor racing and the environment expressed by Mike…
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