Road Test

The Exciting Chevrolet Corvette String Ray

In distinct contrast to Ford of America, General Motors make little effort to sell their U.S.-built cars in Britain, so we entertained no hopes of ever testing the Chevrolet Corvette Sting Ray. But, much to our surprise, Vauxhall Motors called us up three or four months ago and offered a Sting Ray for road test. This offer was naturally accepted and before long a staff member was driving a bright red Sting Ray away from the Lendrum and Hartman workshops in London. Unfortunately, he had not gone very far out of London before one of the drive shafts broke at the outer universal joint, the flailing shaft clearing away some of the undertray, the brake pipes, the shock-absorber and sundry other bits and pieces. In addition, the wheel fell drunkenly inwards as the drive shaft acts as the upper locating member. The car was luckily brought to a stop with no great drama and it was towed ignominiously back to Lendrum and Hartman, where it languished for many weeks while parts were obtained from G.M. in Detroit. Eventually it was in one piece again, and this time a different staff man went to collect the car as the previous driver had suddenly decided he didn't want to drive the Sting Ray any more!

However, this time nothing untoward happened and we were able to put over 1,000 miles on the speedometer of this interesting car. The interesting development story of the Sting Ray can be found on page 250. The Sting Ray features a box-section frame, although it was originally intended to be tubular, but this was found to be uneconomical with a projected output of over 20,000 cars a year. The front suspension is by double pressed steel wishbones with coil-spring/damper units, while the rear end uses a transverse leaf-spring with single lower links, pressed steel radius arms and the unsplined drive shafts acting as upper locating members. Finned drum brakes of 11 in. diameter are fitted all round and steering is of the recirculating ball type. The engine is the typical Chevrolet V8 of 5.3-litres capacity, which is available in 250, 300, 346 and 360-b.h.p. versions. Much to our surprise, when we lifted the bonnet we found we had the most powerful model with the Rochester fuel injection. With this engine one must have the Borg-Warner 4-speed gearbox and the Positraction limited slip differential as this engine is a bit too much for the standard set-up. Other options on our test car were sintered iron brake linings, larger anti-roll bar, stiffer shock-absorbers, larger-than-standard tyres, and electric winding windows.

Naturally, the emphasis of the Sting Ray is on performance, and perform it certainly does. Despite the fact that the 7.60 x 15 in. Firestone Super Sports tyres on the rear wheels had used up most of their tread, our performance figures are some of the best we have ever obtained. We covered the standing-start ¼-mile in 14 sec., with a terminal speed of about 98 m.p.h., without ever straying into the red section of the rev.-counter which commences at 6,500 r.p.m., and from a standstill to 100 m.p.h. occupies only 14.3 sec. The Positraction limited slip differential prevents wheelspin unless the clutch is banged in with over 3,000 r.p.m. on the rev.-counter, and then the car departs very rapidly with large black tyre marks, clouds of smoke and bags of opposite lock correction for the driver. In actual fact, while this impresses bystanders, acceleration times do not benefit greatly from this technique, and as the expensive tyres wear down very timidly indeed, owners will not start in this fashion very often. However, it is not on the test track that the performance is best appreciated, but on the road, where the staggering performance is shown up to its best advantage. Other cars which are travelling quite quickly disappear to a dot on the horizon in an incredibly small space of time once the Sting Ray is past, and there are very few cars which can attempt to hold the Sting Ray for any length of time. Within a few seconds of leaving a built-up area it can be cruising at 100 m.p.h. at a modest 4,500 r.p.m., and at this speed the car feels like most other cars do at 50 m.p.h., for engine and wind noise is kept to a minimum. So confident does one become in the Sting Ray that 100 m.p.h. is used between lorries on short stretches of main road, and the Motorway speed is limited only by bravery and common sense, although with the test car the accent was on bravery for there was a violent transmission vibration which came in at speeds of over 120 m.p.h., and this caused us to desist from determining the car's maximum speed, which should be well in excess of 140 m.p.h. It is unlikely that this vibration is present in other Sting Rays and was probably a legacy of our original drive-shaft breakage. In addition, an irritating gear-lever rattle, equal to anything inflicted on owners of B.M.C.'s Mini, often caused us to drive one-handed, holding the gear-lever with the other hand, or if a passenger was being carried press-ganging this luckless individual into the job.

We expected that the fuel injection engine would be temperamental but it behaved perfectly, starting instantaneously from cold and warming up very rapidly indeed. The rich mixture control on the fuel injection ensures a first-time start and the engine runs cleanly at all times except that it would occasionally stall if the car was braked heavily. If necessary, the car can be left in top gear all the time except for dead stops, and under these conditions the engine showed no sign of temperament at all, while the top-gear acceleration is sufficient to see off most other cars on the road. Indeed, there can be few people who would

willingly go back to a "buzz-box" after sampling the torque of a big V8. The unit is not at all noisy except when running near its rev. limit, and in this respect is undoubtedly quieter than the E-type Jaguar's twin-camshaft engine, although, strangely enough, the American V8 is not as smooth in its delivery of power as the venerable straight-six of the Jaguar.

The gearbox is quite superb, having a great similarity in its feel to the gearbox of the small English Ford range, with short, quick, notchy mechanical movements between the gears. This box cannot be likened to the "knife-through-butter" variety but it has that slight mechanical "clunk" as the gears engage which is, in fact, preferred by many drivers. Reverse is selected by lifting a catch on the gear-lever and moving it beyond 1st gear position, while the other gears are in the normal H-pattern, all of them having synchromesh. First gear is rather high, being able to encompass 65 m.p.h. at 6,500 r.p.m., while 2nd gear will only take in a further 20 m.p.h. Third gear is good for 110 m.p.h., which is about the same as the E-type Jaguar achieves in 3rd gear. If it were not for the gear-lever rattle the gearbox would be very quiet indeed for there is very little gear whine. The same cannot be said of the final drive, which emits loud clonks on occasions, especially when turning sharp corners, and unless the car is cornered with a fair amount of throttle there is some judder from the final drive. This is fairly commonplace with limited slip differentials, and is also noticeable when going forward after a spell of reversing.

It is inevitable that comparisons will be made between the Sting Ray and the E-type Jaguar for they are the only two cars capable of real high performance which are sold in any numbers. One could cite the Aston Martin DB5 or the Ferrari 250GT but these sell in such minute quantities and cost so much that they are not really comparable. In any case we have no experience of them. The E-type and the Sting Ray compete on fairly level terms as regards price in the States, the E-type coupé costing about £1,900 while the Sting Ray lists at £1,400. However, a fairly long list of extras is required on the Sting Ray to bring it near E-type performance, handling and braking, etc., so the cars work out fairly evenly in the long run. In this country there is a colossal difference for the Sting Ray costs nearly £3,500, and not even those enthusiasts who walk around with stars and stripes in their eyes can say that the Sting Ray is worth two E-types. This is probably why there are only one or two Sting Rays in Britain, for even our test car was a left-hand-drive example imported specially from Belgium for a series of road tests.

Fortunately for British enthusiasts who may be regretting the price of the Sting Ray, the car falls short of the standards set by the E-type in respect of handling, steering and braking. The ride is on the firm side, which is not unduly worrying on smooth main roads as any minor undulations are taken quite well and, indeed, under these conditions the floating sensation imparted by the suspension gives the impression that it is too soft, but as soon as rougher roads are reached the ride becomes rather choppy and directional stability becomes affected. We would have liked to have tried the car on a different tyre, like Dunlop RS5 or R6 racing tyres, for the Firestones were badly affected by road surfaces and any longitudinal road imperfections caused the tyres to flick over them laterally. This was especially noticeable on centre white lines and cats-eyes, which produced audible thumping from the suspension. This harshness and wandering tendency is not so pronounced at the lowest recommended tyre pressures of 24 lb. all round, but with the 10 lb. additional pressure recommended for high-speed work the suspension is very firm indeed and at high speed the driver has to concentrate pretty carefully to keep the car on a straight course.

On smooth, dry roads the handling can be quite exhilarating and after practising on the test track we felt more confident in the car than we had in our previous experience on the road. There is quite strong understeer, which is especially noticeable on the lower tyre pressures, and fast driving on winding roads could well become tiring. With 360 b.h.p. available little effort is needed to provoke the tail to come round, and with practice corners can be taken in gentle tail slides. However, care has to be taken with the throttle for even as little as ¼ in. too much throttle can turn an expert slide into an ignominious spin! This technique must be used with care on the roads, for an unexpected bump on the apex of a corner can send the car off line easily. The car is not too keen to corner on a trailing throttle or light throttle opening and when the driver opens up after so doing the tail tends to swing. On wet roads, with our near-bald tyres, we set off on trips with some reluctance, and it was necessary to drive very gingerly indeed for the tail would slide quite easily even when the car was travelling in a straight line.

The recirculating ball steering is commendably light for a non-assisted layout but of course it cannot compete with rack-and pinion for lightness and precision. It does not suffer from the rack-and-pinion's tendency to kick back and is, in fact, a very good compromise. It is geared 3.4 turns lock-to-lock but the steering arms have two attachment points for the tie rods and by remounting the rods the ratio is reduced to 2.9 turns. The slowest ratio is quite adequate for most normal uses but with a car having the power of the Sting Ray you can hardly have too quick steering. Power assistance is an optional extra. The steering column is not adjustable for length and most tall drivers felt that they could do with the wheel a little farther away. This could be easily organised as the present wheel is deeply dished and a replacement wood-rimmed wheel would give another 2 in. reach.

The brakes are still of the drum variety and one can only assume that this is because the disc brake is a virtual British monopoly, for the drums have little to recommend them. Despite having the optional sintered iron linings the brakes seldom reacted consistently and if used harshly without warming them up gently beforehand they would grab to one side or the other, and whilst it was difficult to provoke fade they never felt 100% efficient when driving hard on winding roads. A vacuum servo gives light, progressive pedal pressure.

The fuel tank in the tail of the car holds 20 U.S. gallons, which is approximately 16½ Imperial gallons, and a racing option is 36 U.S. gallon tank. With a car weighing 1½ tons and a claimed output of 360 b.h.p. we expected the consumption to be ruinous but we achieved an overall consumption of 15 m.p.g. and averaged nearly 17 m.p.g. on a cross-country trip using plenty of acceleration and a top speed of 100 m.p.h. However, it is a sobering thought that it costs over £4 to fill the tank of this car, which will suffice for only 220-240 miles.

It is the external appearance and internal layout of the Sting Ray that the British enthusiast will find most distasteful, for it is as vulgar and over-ornamented as the E-type is simple and functional. The basic shape of the car is quite pleasing but it is completely spoiled by dummy louvres in the bonnet, and false vents in the front wings and body sides, while various insignia are scattered over the body announcing that the car is a Sting Ray, has fuel injection and is made by Chevrolet; in addition, the opportunity is taken several times to place crossed flags in prominent places, including the large petrol tank flap. The surface finish of the car is the best we have ever seen in glass-fibre and many people would not believe that it wasn't steel until they had tapped it with their knuckles. It is impossible to tell from the under surface whether it is glass-fibre for there are none of the straggling bits and pieces normally seen on glass-fibre bodies. The test car was actually a 1963 model but the 1964 models have slight modifications, including the deletion of the central dividing strip in the rear window, which allows some measure of rearwards vision.

The interior was trimmed in a rather lurid red plastic, matching the bright red bodywork, the facia being arranged in two symmetrical cowls with a central console. The driver is plentifully supplied with instruments, including speedometer, tachometer, oil-pressure, water-temperature, ammeter and fuel gauges. A large and erratic electric clock is mounted centrally, while the passenger merely has a glove locker, above which is a grab handle. The minor controls are fairly conventional. The 2-speed wipers tend to lift off the screen at over 80 m.p.h., while the washers prefer to spray passing cars rather than the screen. The handbrake is an umbrella type under the facia, which isn't much use on a sports car but has a flashing warning light to remind the driver that it is on. The headlights are hidden behind flaps normally and these are raised by a switch under the facia. This takes a long time so daylight flashing is out of the question unless the lamps are permanently raised. A normal push-pull switch and foot dipper controls the excellent lights. The two switches for the side windows are on the central tunnel and, while we normally class electric windows along with automatic transmission, it must be admitted that it takes much of the fag out of raising and lowering the windows. A good fresh-air heater is fitted and cold air vents are also supplied. The test car was fitted with a radio, which failed during our test.

The seats are quite comfortable but are not of the true bucket type. They have a good range of fore-and-aft adjustment and six-footers can make themselves comfortable. The standard rake of the back-rest is rather upright but small adjustments can be made. The driver has an excellent view but gains the impression of sitting on the car rather than in it as with most sports cars. The seat backs fold forward to gain access to the large rear compartment. Seats could be fitted for small children in this compartment but an adult would be very uncomfortable. It is somewhat difficult to load large items into the space behind the seats.

Despite its various shortcomings it is impossible to ignore the appeal of the Sting Ray for it offers tremendous performance even by American standards, and while it falls below the ideal in respect of ride, handling and braking, it is still an impressive piece of machinery by any standards. As a status symbol in Europe it is unsurpassed for you are hardly likely to meet another, and wherever we went people stopped us and questioned us closely, and even asked if they could take photographs. At present Jaguar have little to fear from the Sting Ray but in America development seems to go ahead very rapidly and next year's Sting Ray may well be a vast improvement. Now if only Jaguar had that engine and gearbox!—M. L. T.

Chevrolet Corvette Sting Ray Sports Coupé

Engine : Eight cylinders, 101.6 x 83.5 mm. (5,363 c.c.). Push-rod-operated overhead valves. 11.25-to-1 compression ratio. 360 b.h.p. (gross) at 6,000 r.p.m.

Gear ratios : 1st, 8.15; 2nd, 6.06; 3rd, 4.85; top, 3.70.

Tyres : Firestone Super Sports : front, 6.50/6.70 x 15 in.; rear, 7.10/7.60 x15 in.

Weight : 1 ton 9 cwt. 0 qtr. 5 lb. (without occupants but with 10 gallons fuel).

Steering ratio : 3.4 turns lock-to-lock.

Fuel capacity : 16½ gallons. (Range approximately 230 miles.)

Wheelbase : 8 ft. 2 in.

Track : Front, 4 ft. 8¼ in.; rear, 4 ft. 9 in.

Dimensions : 14 ft. 7¼ in. x 5 ft. 9½ in. x 4 ft. 2 in. (high).

Price : £2,750. Total with tax, £3,323 9s. 71. (Prices of extras not available.)

Manufacturers : General Motors Corporation, Detroit, U.S.A.

Performance Data

0-30 m.p.h. .. 2.5 sec. (2.4 sec.)

0-40 m.p.h. .. 3.5 sec. (3.3 sec.)

0-50 m.p.h. .. 4.6 sec. (4.5 sec.)

0-60 m.p.h. .. 6.0 sec. (5.9 sec.)

0-70 m.p.h. .. 7.9 sec. (7.9 sec.)

0-80 m.p.h. .. 9.7 sec. (9.5 sec.)

0-90 m.p.h. .. 12.2 sec. (12.1 sec.)

0-100 m.p.h. .. 14.3 sec. (14.3 sec.)

Standing-start ¼-mile .. 14.0 sec. (14.0 sec.)

(Figures in parentheses are best times)

Speed in gears : 1st, 65 m.p.h.; 2nd, 85 m.p.h.; 3rd, 110 m.p.h.; top, 145 m.p.h. (estimated). See text.