The MG Midgets
In America in the ‘50’s bigger was better, and biggest was the best, and the normal label for the smallestsize product was "giant." The US car makers from Detroit were loathe using the term “compact” and would avoid using the term when they could. Therefore it would seem that there would be little room here for a car called the "Midget." There was one, the King Midget - but it had never been one of the all-time big sellers.
With the demise of the TF and the birth of the MGA, in 1955, MG allowed the "Midget" name to disappear, ending a series that had been unbroken since 1929.
Only six years later the name was revived for a new line of MG cars with a price once again under AU$2,500 - cars that were small in size but “Midgets" in name only.
In 1957 the British Motor Corporation centred most of its sports car manufacturing at the original MG factory at Abingdon-on-Thames. One of the cars that made the big move was the Austin-Healey Sprite, then being readied for its mid-1958 debut. The bug-eyed Sprite, the handiwork of Donald and Geoff Healey at their design office at Warwick, was cleverly designed to use many parts from the BMC bins at Longbridge in a neat and very simple structure.
After three years or so BMC decided to update the Sprite, handing the job to John Thornley and the staff of Abingdon. As Thorn1ey said “We managed to get rid of that rather distinctive frog-like look just when it had latched on and become an acceptable gimmick, but we were driven into this by probably misplaced adverse criticism." Sprite fans resented the loss of the distinctive headlights, but lovers of MG's, of whom there were many, benefited from the change to a more conventional front end, which made it possible for BMC to indulge in a little more of what its critics sometimes call "badge engineering."
As it did with most of its small and medium-sized cars, BMC decided to put two different nameplates on the revised small sports car. The new wide grille opening was laid out to accept the vertical MG bars as well as the Sprite grille. In July 1961, the MG Midget was reborn, as a slightly plusher companion car to the Sprite. It cost a little more, $2,300 versus $2,278 for the Sprite II which had a more deluxe interior trim and some Sprite options as standard. In spite of the added cost the appeal of the MG name was such that the Midget soon outsold its sister.
The Power Unit
The first post-war Midgets had engines smaller than one litre, a type not seen since the overhead-cam PB of 1936. The unit was the BMC A-type engine, one that dated back in design to 1951. It was introduced then to power the Austin A30 sedan, a little 803cc unit developing 28bhp at 4800rpm. It was a typical British long-stroke pushrod engine of 58 by 76.2mm. In 1956 the bore was enlarged to 62.9mm, bringing the displacement to 948cc.
This change, along with a compression ratio increase to 8.3 to one, was made possible by the use of more durable Vandervell thin-wall bearing shells. It also required the joining of the front and rear pairs of cylinder walls. This little engine was now lively enough to be chosen to power the new Midget, spiced up further through the use of some of the data gathered by BMC when it was developing Formula Jumor racing engines for John Cooper's successful cars.
Slightly larger intake valves and longer intake cam timing helped extend the rev range, bringing the peak output to 49.5 bhp at 5500rpm. With twin 290cm S.U. carburettors and a 9 to one compression ratio, peak torque of the engine is 7.26 metre-kgs at 4000rpm. Formula Junior breeding gave the engine a wide range as well as useful power. There was a noticeable vibration period between 5000 and 55000rpm, but the engine will rev easily past 6000 to its valve bounce speed, in stock form, of 6500rpm. When driven normally, it was capable of returning fuel consumption consistently above the 7.84 litres per 100 kms mark, which is an important feature in a car with a 33 litre fuel tank.
Major engine refinements were made late in 1962, when the bore was increased yet again to 64.6mm, and the stroke stretched to 83.7mm. With the new displacement of 1098cc the compression ratio was lowered fractionally to 8.9 to one. Output rose to 56bhp at a slightly higher peak speed, 5750rpm, and torque also rose to 8.43 metre-kgs, the peak figure on a very flat, strong curve. Valve bounce set in a little earlier on this engine, at 6300, but through the rest of its range it was smoother than the earlier Midget engine.
These early Midget engines were modified in several different styles for racing, again using Formula Junior techniques. A popular conversion was to a 45mm side-draft twin-throat Weber carburettor, on a special cast aluminium ram-length manifold. These were used on the special GT Midgets built by the factory in 1962 for the Dick Jacobs team.
They were also used by Speedwell for their "Clubman 85" version of the Midget. Speedwell fitted special pistons giving an 11-to-one compression ratio in the 1098cc engine, balanced and polished all the internal rotating and reciprocating parts, and wound the pushrod four out to 7000rpm for its peak power of 87bhp. The engine didn't have much below 4000 but it would wind safely to 7500rpm.
Shifting and Stopping
A tiny clutch, only 1,560cm in diameter, was used on the 948cc Midgets for which it was just barely adequate for hard driving. A 1,813cm clutch came in with the 1098cc engine. Both the clutch and transmission were encased in one-piece aluminium housing with a rearward extension for the remote-control lever. Reverse gear was to the right of neutral and rearward, a reversion to the layout used on the TD and TF.
The standard Midget gear ratios were perfect for enjoyable road driving, giving speeds of 48, 80 and 112kph in first, second and third. In fourth the Midget cruises nicely at 104kph, with just 4000rpm at 60mph, recalling the identical relationship on the TC. Optional ratio sets were offered for the early Midgets, one a wide-ratio gearbox with a 3.63-to-one low, standard being 3.20. The close-ratio option had a 2.93-to-one low gear.
Early Midgets had very simple cone-type synchromesh
for the top three forward speeds, a type that can easily be overcome in fast shifting. In racing this was no problem because speed was the objective, and the early box shifts fast. But in road use the later box, introduced with the 1098cc engine, was more pleasant. It had a type of synchromesh
that kept the gears from engaging until their relative speeds were close to identical.
Like the clutch, the original Midget brakes
were fine for normal driving but not up to really hard road use or racing. Only 18cm in diameter, the drum brakes
called for a fair amount of pressure on a pedal with a "dead" feel. They would stop the car, but then fade could become a factor also. In acknowledgement Abingdon made various options available for racing, including 20cm front brakes
(part number AT A 7154), aluminium brake drums made by the Al-Fin process, and sets of disc brakes
for the front wheels and also for all four wheels.
A vast improvement in the production car was made in late 1962, along with the 1098cc engine. Lockheed disc brakes
were standardised for the front wheels. At 20.95cms in diameter, with shields warding off road dirt and splash, these brakes
greatly improved both the stopping power and the fade resistance.
At the front wheels (disc in early Midgets, optional Wires later), the suspension was conventional coil and parallel wishbone type. The upper arm, as on the larger MG, was integrated with the input shaft of the lever-type shock absorber. Rack-and-pinion steering
was mounted ahead of the wheel centreline, and its quick ratio gave only 2 1/4, turns from lock to lock.
Front-end grease nipples were among the 12 total on the Midget that need servicing every 1,600 kms on early cars, every 4,828 kms on the later models. The number of points was still excessive by maintenance standards. At the rear the Healeys worked out a novel means of springing the live axle of the Sprite, and hence the Midget, which by the way had a normal axle ratio of 4.22 to one. Optional ratios are 3.73, 4.55, 4.88, 5.12 and 5.38 to one. Brackets at the ends of the axle tubes attached them to high-placed trailing radius arms and, below them, to trailing leaf springs which both suspend and guide the axle.
Each spring located the axle laterally and did quite a lot of work considering it was a short spring.. Fifteen slim leaves composed each spring, which was clamped firmly at its thick end to the integrated chassis frame, just behind the seats. This means that all the main rear stresses go into the centre part of the body/frame, none were fed into the overhung rear boot portion.
The layout looked correct, but in practice it did limit the rear axle travel, making the ride very bouncy on rough roads. It also guided the axle in such a way as to highlight any oversteer, which was no fault in a lively sports car but which gave the early Midgets a super-responsive feel. These cars are "thought" rather than steered around corners, calling for just a finger-touch on the wheel for most driving. Heavy-handed thrashing at the wheel sent the little car darting all over the road.
MG recommended rear tyre
pressures that were 2 p.s.i. higher than those at the front, which was an imbalance in the direction to reduce oversteer. Some drivers found that a differential of 6 p.s.i.-for example 22 front and 28 rear-helped a great deal to make the Midget more stable on expressways and modified its superquick steering
response. An optional front anti-roll bar
could also add a dose of understeer that improved stability in fast corners.
Body and Assembly
The basic structure of the Midget was a very simple platform type frame, integrated with the body and strengthened by its front and rear portions, as well as the cowl structure. On the Sprite the whole front part of the body lifted for access to the engine and suspension; this was discontinued on the Midget and Sprite II but the original separation lines on the side of the body remained. It was not an elaborate frame but it was one that worked, offering high rigidity over a 203 cm wheelbase with a curb weight of only 714 kgs.
From the Sprite the first Midgets inherited a flat, simple dash panel with an adequate supply of dials and a yellowish two-spoke plastic steering
wheel which was perhaps the car's least sporty feature. The seats were comfortable, with adequate if not excessive front-rear adjustment. An option was a cushion for the carpeted area behind the seats. Kids could crouch on this in a knees-up position but otherwise it was more for ornamental than practical.
A huge duct through the engine room took fresh air to the heater fan, and then through the heating core, which was connected to the engine's water system through an under-hood tap which was to be turned off during the summer. On later cars of the first series, the heater's output was gradually and significantly improved.
All these final touches were installed along the assembly lines at Abingdon, not the facility owned by British Leyland Motors but one well suited to specialised manufacturing. The complete and painted body/chassis units arrived on trucks, then were placed on dollies for their ride down the line. Wiring harnesses, instruments and lights went in first before the exterior trim and windshield arc were fitted.
Front and rear suspension assemblies rose from below for attachment to the nearly complete body. After this, the engine/ gearbox assembly was swung down and threaded into the tunnel. The 33 cm wheels were spun on and the Midget rolled down to ground level for the fitting of the radiator
and the MG grille.
Finally the top was put up, the battery
connected and the car driven out of the factory for a routine 11 km road test. Was the driver aware that he was handling
"a racy, rocket-swift, roadhugging gamester with the grace, dash and power of a lion," as MG's U.S. ads proclaimed? To him the job was probably a routine one - as routine as it could possibly be to drive sports cars for a living.
Midget Marks II and III
The most important changes in the history of the later Midget were made public in March, 1964, with the unveiling of the Mark II version. Immediately obvious was the adoption of front quarter windows and real wind-up side glass, bringing the smaller MG in line with the MGB. Outside door handles and locks, as well as burst-resistant door handles, added both convenience and safety. The only drawback of the change was the reduction in the already limited elbow-room in the 135cm wide Midget, through the door space taken up by the windows.
Vast interior improvements in the Mark II included a new contoured dash, with the main dials angled towards the driver and a low package shelf ahead of the passenger. A new three-spoke steering
wheel recalled the design used on the MGB, and another "B" feature was the central windshield tensioning rod along which the rear-view mirror can slide for adjustment. (The original dash mounted mirror was far too low for most drivers.)
In spite of all these deluxe additions, the Mark II increased in weight only 2.7 kgs. At the same time, the rear springing was replaced by a conventional spring arrangement. This eliminated the rear radius rods, part of the spring weight, and much of the body structure stiffening needed to anchor the springs properly.
The new rear suspension proved better as well as lighter. The ride of the Mark II Midget was noticeably improved, though still firm in the British sporting manner. handling
became less jerky and more predictable, though still extremely precise. In 1967
Syd Enever came up with the Mark III version. The engine was completely revised, enlarged to 1275cc with a yet larger bore, 70.6mm, and a shortened stroke, down to 81.3mm. At last the little MG engine was beginning to approach cars of its era that had "square" proportions.
The compression ratio remained high, at 8.8 to one, still calling for premium fuel. In its latest guise, burdened with an air-injection pump to reduce exhaust
emissions, the Mark III engine produced 62bhp at 6000rpm. Much more substantial compared to earlier Midget engines was its torque. A better idea from Abingdon for the Mark III was an installed top, a major improvement over the old bullfighter's-cape style. After all these changes the Midget's price naturally rose, but at AU$2,701 with wire wheels, now standard equipment, it was an amazing bargain. You literally couldn’t buy more fun for the money.
Also see: MG Heritage
| Sprites and Midgets