The MGB is a two-door sports car manufactured and marketed from 1962 until 1980 by the British Motor Corporation (BMC), later the Austin-Morris division of British Leyland, as a four-cylinder, soft-top sports car. It was announced and its details first published on 19 September 1962.[3] Variants include the MGB GT three-door 2+2 coupé (1965–1980), the six-cylinder sports car and coupé MGC (1967–69), and the eight-cylinder 2+2 coupé, the MGB GT V8 (1973–76).

Replacing the MGA in 1962, production of the MGB and its variants continued until 1980. Sales for the MGB, MGC and MGB GT V8 combined totaled 523,836 cars. After a 12-year hiatus, the MGB re-entered production as the heavily modified MG RV8 with a limited run of 2,000 cars before finally being replaced in 1995 by the MG F.

History
Development of the MGB started at least as early as 1958 with the prototype known by its Abingdon codename; MG EX205.[4] In structure the car was an innovative, modern design in 1962, utilizing a unitary structure, instead of the traditional body-on-frame construction used on both the MGA and MG T-types and the MGB's rival, the Triumph TR series.[5] However, components such as brakes and suspension were developments of the earlier 1955 MGA, with the B-Series engine having its origins in 1947. The lightweight design reduced manufacturing costs while adding to overall vehicle strength. Wind-up windows were standard, and a comfortable driver's compartment offered plenty of legroom. A parcel shelf was fitted behind the seats.

The MGB achieved a 0–60 mph (97 km/h) time of just over 11 seconds. The three-bearing 1,798 cc B-Series engine produced 95 hp (71 kW) at 5,400 rpm – upgraded in October 1964 to a five-bearing crankshaft. From 1975, US-market MGB engines were de-tuned to meet emission standards, ride height was increased by an inch (25 mm), and distinctive rubber bumpers were fitted to meet bumper standards.

The MGB was one of the first cars to feature controlled crumple zones designed to protect the driver and passenger in a 30 mph (48 km/h) impact with an immovable barrier (200 ton).[6][7] Nevertheless, the British AA motoring association has described the car, like many other classic models, as much less safe than modern cars. The issue received public attention following a 2013 case in which a driver in a hired 1963 MGB was killed in a collision with a taxi.[8]

A limited production of 2,000 units of the RV8 was produced by Rover in the 1990s. Despite the similarity in appearance to the roadster, the RV8 had less than 5% parts interchangeability with the original car.

Drivetrain

A sectioned MGB showing engine and gearbox configuration
All MGBs (except the V8 version) used the BMC B-Series engine. This engine was essentially an enlarged version of that used in the MGA with displacement being increased from 1,622 to 1,798 cc. The earlier cars used a three-main-bearing crankshaft, 18G-series. In February 1964 positive crank-case breathing was introduced and the engine prefix changed to 18GA, until October 1964, when a five-bearing crankshaft design was introduced, the engine prefix became 18GB. Horsepower was rated at 95 net bhp on both five-main-bearing and earlier three-bearing cars with peak power coming at 5,400 rpm with a 6,000 rpm redline. Torque output on the MGB had a peak of 110 lb⋅ft (150 N⋅m) and fuel consumption was around 25 mpg.[9] US specification cars saw power fall in 1968 with the introduction of emission standards and the use of air or smog pumps. In 1971 UK spec cars still had 95 bhp (71 kW) at 5,500 rpm, with 105 lb⋅ft (142 N⋅m) torque at 2,500 rpm. Engine prefixes became 18V and the SU carburettor needles were changed for reasons of the latest emission regulations, under ECE15. By 1973 it was 94 bhp (70 kW); by 1974 it was 87, with 103 lb⋅ft (140 N⋅m) torque; by 1975 it was 85 with 100 lb⋅ft (140 N⋅m). Some California specification cars produced only around 70 hp (52 kW) by the late 1970s. The compression ratio was also reduced from 9:1 to 8:1 on US spec cars in 1972.

All MGBs from 1963 to 1974 used twin 1.5-inch (38 mm) SU carburettors. US spec cars from 1975 used a single Stromberg 1.75-inch (44 mm) carburettor mounted on a combination intake–exhaust manifold. This greatly reduced power as well as created longevity problems as the (adjacent) catalytic converter tended to crack the intake–exhaust manifold. All MGBs used an SU-built electric fuel pump.

All MGBs from 1962 to 1967 used a four-speed manual gearbox with a non-synchromesh, straight-cut first gear. Optional overdrive[10] was available. This gearbox was based on that used in the MGA with some minor upgrades to cope with the additional output of the larger MGB engine. In 1968 the early gearbox was replaced by a full synchromesh unit based on the MGC gearbox. This unit was designed to handle the 150net bhp of the three-litre engine of the MGC and was thus over-engineered when mated with the standard MGB B-Series engine. The same transmission was used in the 3.5-litre V8 version of the MGB-GT-V8. An automatic three-speed transmission was also offered as a factory option, but was unpopular.

Electrically engaged overdrive gearboxes were an available option on all MGBs. The overdrive unit was operational in third and fourth gears (until 1977, when overdrive was only operational in fourth)[11] but the overall ratio in third gear overdrive was roughly the same as fourth gear direct. The overdrive unit was engaged by a toggle switch on the dashboard. The switch was moved to the top of the gearshift knob in 1977.[11] Overdrives were fitted to less than 20% of all MGBs.

There were three different types of overdrive transmissions fitted to the MGB.

1962–64, 1965–67

Laycock Type D OD (note external solenoid)
A hole in the bell housing where the starter nose poked through
"Shield" shaped access cover
1020 TPM for OD and 1040 TPM for non-OD
The gearbox input shaft, flywheel and engine backing plate were changed with the advent of the five-main-bearing engine in 1965. Therefore, the transmission for a three-main-bearing engine (1962–1964) differed from its later counterpart.

1968 to 1974.5

Laycock Type LH OD
Rectangular shaped access cover
Oval clutch fork boot
Dipstick (for checking oil)
Black label on the OD solenoid cover stamped "22/61972"
1280 TPM for OD and non-OD
Speedometer drive gear (on the mainshaft) was blue
Speedometer driven gear (on removable drive housing) was white with 21 teeth

1974.5 to 1980

Laycock Type LH OD
Rectangular shaped access cover
Square clutch fork boot
Side fill plug (no dipstick)
Blue label on the OD solenoid cover stamped "22/62005"
1000 TPM for OD and non-OD
Speedometer drive gear (on the mainshaft) was red
Speedometer driven gear (on removable drive housing) was red with 20 teeth
Overdrive operated in fourth gear only in units made from February 1977 onward.[11]


A sectioned MGB showing the rear axle and differential
Early MGBs used the "banjo" type differential carried over from the MGA with the rear axle ratio reduced from the MGA's 4.1 (or 4.3) to 3.9 to 1. (Compensating for the reduction from 15 inch to 14-inch (360 mm) wheels). MGB GTs first began using a tube-type rear axle in 1967. This unit was substantially stronger, being, like the later gearbox, designed for the three-litre MGC. All MGBs used the tube-type axle from 1968.

All MGBs were fitted with 11-inch (280 mm) solid (non-ventilated) disc brakes on the front with drum brakes on the rear. The front brake calipers were manufactured by Lockheed and used two pistons per caliper. The brake system on the MGB GT was the same as the roadster with the exception of slightly larger rear brake cylinders. A single-circuit hydraulic system was used before 1968 when dual-circuit (separate front and rear systems) were installed on all MGBs to comply with US regulations. Servo assistance (power brakes) was not standard until 1975. Many modern and contemporary testers have commented on the very heavy brake pedal pressure needed to stop the non-servo-assisted cars.[citation needed]

The MGB initially had an extremely simple electrical system. Dash-mounted toggle switches controlled the lights, ventilation fan, and wipers with only the direction indicators being mounted on a stalk on the steering column. The ignition switch was also mounted on the dash. Like the MGA, the MGB utilized two 6-volt batteries wired in series to give a 12-volt positive earth configuration. The batteries were placed under a scuttle panel behind the seats making access difficult; the location gave excellent weight distribution and thus improved handling. The charging system used a Lucas dynamo. Later MGBs had considerable changes to the electrical system including the use of a single 12-volt battery, a change from positive to negative earth, safety-type toggle (rocker) switches, alternator in lieu of dynamo, additional warning lights and buzzers, and most common functions moved to steering column stalks.

From 1972 there were two different Pirelli Cinturato radial tyre sizes factory-fitted to new cars, depending on whether the car was a roadster,(155/80x14) or a GT,(165/80x14).The original tyres for the majority of MG B’s were 165HR14 Pirelli Cinturato.[12] With the 1974.5 arrival of the rubber bumper cars the factory-fitted tyre size was simplified to 165/80x14 for all cars, irrespective of whether the car was a roadster or a GT, and also irrespective of the wheel type (wire or RoStyle). Later on during the rubber bumper production period, alloy wheels were introduced on several different limited edition models - with the final 1,000 LE models being the last cars to leave the factory with alloy wheels. The factory built V8s were fitted with full profile 175HR14 tyres.

MG began offering the MGB GT V8 in 1973 powered by the aluminium block 3,528 cc Rover V8 engine, first fitted to the Rover P5B. This engine had been used in the unibody GM 1961–1963 A-body platform Buick Special/Skylark and Oldsmobile F-85 and 1961–1962 Pontiac Tempest and was the lightest mass-production V8 in the world.

The Buick version had a dry, undressed weight of 318 lb (144 kg) and the 1963 Skylark with optional four-barrel Rochester carburettor and 10:1 compression ratio produced 200 hp (150 kW) at 5,000 rpm. By the time Rover had made webbing modifications to strengthen the block, the engine was considerably heavier (over 170 kg). Some changes were made by MG-Rover and the engine found a long-lived niche in the British motor industry.

These cars were similar to those already being produced in significant volume by tuner Ken Costello. MG even contracted Costello to build them a prototype MGB GT V8. However, the powerful 180 bhp (134 kW) engine used by Costello for his conversions was replaced for production by MG with a more modestly tuned version producing only 137 bhp (102 kW) at 5,000 rpm. Nonetheless, 193 lb⋅ft (262 N⋅m) of torque helped it hit 60 mph (97 km/h) in 7.7 seconds and go on to a 125 mph (201 km/h) top speed. Fuel consumption was just under 20 mpg.

By virtue of its aluminium cylinder block and heads, the Rover V8 engine weighed approximately 40 pounds less than MG's iron four-cylinder. Unlike the MGC, the V8 that provided the MGB GT V8's increased power and torque did not require significant chassis changes nor sacrifice handling.

Both chrome and rubber-bumpered GT versions of the V8-powered MGB were produced by the factory with production ending in 1976.

MG never attempted to export the MGB GT V8 to the United States. It chose not to develop a left-hand-drive version of the MGB GT V8 although the Rover V8 engine was offered in US-bound Rover models. The P6 3500 was withdrawn after 1971 from the US and the Rover 3500 SD1 only introduced in 1980 (its engine equipped with power-sapping emissions equipment) so that during the lifetime of the MGB GT V8 the engine was not being built in a federal version. Abingdon built seven LHD models, sent them to America to achieve certification, and brought them back to the UK to be sold to mainland European countries.

The MG T series is a line of open two-seater sports cars with body structure and very little protection against the elements that were produced by MG from 1936 to 1955. The series included the MG TA, the MG TB, the MG TC, the MG TD, and MG MG Midget models. The last of these models, the TF, was replaced by the MGA.

The name TF was reinstated in 2002 in the mid-engined MG TF sports car.

The TF Midget, launched on October 15, 1953, was a faceted TD, equipped with the TD Mark II engine, headlights on the fenders, an inclined radiator grille concealing a separate radiator and a new pressurized cooling system along with a simulated external radiator cap. [1] The compression ratio of this XPAG engine has been increased to 8.1: 1 and extra-large valves with stronger valve springs and larger carburetors have increased production to 57.5 hp at 5,500 rpm.

In mid-1954, the engine's capacity was increased by 17% to 1466 cc and called XPEG. The diameter was increased to 72 mm (2.8 in) and the compression increased to 8.3: 1, giving 63 CV (47 kW) at 5,000 rpm and a 17% increase in torque. The car was designated TF1500, and externally distinguished by a cream-colored enamel nameplate on both sides of the hood, placed only on the rear of the front cover release buttons.

Production ended at chassis number TF10100 on April 4, 1955, after 9,602 TFs were manufactured, including two prototypes and 3,400 TF1500s. TF was replaced by MGA.

 

The MGA is a sports car that was produced by MG from 1955 to 1962.

The MGA replaced the MG TF 1500 Midget and represented a complete styling break from MG's earlier sports cars. Announced on 26 September 1955[3] the car was officially launched at the Frankfurt Motor Show. A total of 101,081 units were marketed through the end of production in July 1962, the vast majority of which were exported. 5869 cars were sold on the home market, and the MGA was replaced by the MGB.


Design
The MGA design dates back to 1951, when MG designer Syd Enever created a streamlined body for George Philips' TD Le Mans car. The new bodywork traded the MG TF's articulated fenders and running board for ponton styling, with a single styled envelope fully enclosing the width and uninterrupted length of a car.

The TF featured a high driver seating position. A new chassis was designed with the side members further apart and the floor attached to the bottom rather than the top of the frame sections. A prototype was built and shown to the BMC chairman Leonard Lord. He turned down the idea of producing the new car as he had just signed a deal with Donald Healey to produce Austin-Healey cars two weeks before. Falling sales of the traditional MG models caused a change of heart, and the car, initially to be called the UA-series, was brought back. 

As it was so different from the older MG models it was called the MGA, the "first of a new line" to quote the contemporary advertising. There was also a new engine available, therefore the car did not have the originally intended XPAG unit but was fitted with the BMC B-series engine allowing a lower bonnet line. The MGA convertible had no exterior door handles, however the coupe had door handles.

It was a body-on-frame design and used the straight-4 "B series" engine from the MG Magnette saloon driving the rear wheels through a four-speed gearbox. Suspension was independent with coil springs and wishbones at the front and a rigid axle with semi-elliptic springs at the rear. Steering was by rack and pinion. The car was available with either wire-spoked or steel-disc road wheels.