Very cool MGB GT sighted today with owner - for my friend Kunio Miyauchi - Jon Hammond en.wikipedia.org/wiki/MG_MGB The MGB is a sports car launched by MG Cars in May 1962, replacing the MGA. Introduced as a four-cylinder roadster, a coupé with 2+2 seating was added in 1965. In addition, the six-cylinder MGC was launched in 1967, and a later derivative, the MGB GT V8 fitted with the Buick-based Rover V8, replaced it from 1973 to 1976. MGB/MGC production continued until October 1980 by the British Motor Corporation and its successors, British Motor Holdings and British Leyland Motor Corporation. The bodyshell was reprised in modified form with a limited run of 2,000 MG RV8 roadsters, built between 1993 and 1995. In structure the MGB was an innovative, modern design in 1962, utilizing a monocoque structure instead of the traditional body-on-frame construction used on both the MGA and MG T-types and the MGBs rival, the Triumph TR series.[3] 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 drivers compartment offered plenty of legroom. A parcel shelf was fitted behind the seats. The MGBs performance was considered brisk at the time of its introduction, with a 0–60 mph (96 km/h) time of just over 11 seconds, aided by the relatively light weight of the car. Handling was one of the MGBs strong points. The 3-bearing 1798 cc B-Series engine produced 95 hp (71 kW) at 5,400 rpm. The engine was upgraded in October 1964 to a five-bearing crankshaft in an effort to improve reliability. The majority of MGBs were exported to United States. In 1975, as US air pollution emission standards became more rigorous, US-market MGBs were de-tuned for compliance. As well as a marked reduction in performance, the MGB gained an inch (25 mm) in ride height and the distinctive rubber bumpers which came to replace the chrome for all markets. 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).[4][5] Combined production volume of MGB, MGC and MGB GT V8 models was 523,836 cars. A very limited-production revival model with only 2,000 units made, called RV8 was produced by Rover in the 1990s. Despite the similarity in appearance to the roadster, the RV8 had less than 5 percent parts interchangeability with the original car. Drivetrain[edit] A sectioned MGB showing engine and gearbox configuration. Engine: All MGBs (except the V8 version) utilized the BMC B-Series engine. This engine was essentially an enlarged version of that used in the MGA with displacement being increased from 1622 cc to 1798 cc. The earlier cars used a three main bearing crankshaft, 18G-series. In February 1964 positive crank-case breathing was introduced and engine prefix changed to 18GA, until October 1964, when a five-bearing crankshaft design was introduced, engine prefix became 18GB. Horsepower was rated at 95net bhp on both 5 main bearing and earlier 3-bearing cars with peak power coming at 5400 rpm with a 6000 rpm redline. Torque output on the MGB is good with a peak of 110 lb·ft (150 N·m) Fuel consumption was around 25mpg.[6] 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 2500 rpm. Engine prefix 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 to 1 to 8:1 on US spec cars in 1972. Carburation: 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 creating longevity problems as the (adjacent) catalytic converter tended to crack the intake–exhaust manifold. All MGBs used a SU-built electric fuel pump. Gearbox:: All MGBs from 1962 to 1967 used a four-speed manual gearbox with a non-synchromesh, straight-cut first gear. Optional overdrive[7] 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 3-litre engine of the MGC and was thus over-engineered when mated with the standard MGB B-Series engine. In fact, the same transmission was even used in the 3.5-litre V-8 version of the MGB-GT-V8. An automatic three-speed transmission was also offered as a factory option but proved to be fairly 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)[8] 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 located on the dashboard. The switch was moved to the top of the gearshift knob in 1977.[8] Overdrives were fitted to less than 20% of all MGBs, making it a very desirable feature. There were three different types of overdrive transmissions fitted to the MGB. 1962-1964, 1965-1967 Laycock Type D OD (note external solenoid) A hole in the bell housing where the starter nose pokes through “Shield” shaped access cover 1020 TPM for OD and 1040 TPM for non-OD Note: The gearbox input shaft, flywheel and engine backing plate were changed with the advent of the 5 main bearing engine in 1965. Therefore, the transmission for a 3 main bearing engine (1962-1964) differs from its later counterpart.[8] 1968 through 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) is blue Speedometer driven gear (on removable drive housing) is white with 21 teeth [8] 1974.5 through 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) is red Speedometer driven gear (on removable drive housing) is red with 20 teeth Note: Overdrive operates in 4th gear only in units made from February 1977 onward.[8] A sectioned MGB showing the rear axle and differential. Rear axle: Early MGBs used the banjo type differential carried over from the MGA with the rear axle ratio reduced from the MGAs 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. Brakes: 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 Girling 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] Electrical system: 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 a bit of a challenge but 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 twelve-volt battery, a change from positive to negative earth, safety-type toggle switches, an alternator in place of the dynamo, additional warning lights and buzzers, and having most common functions moved to steering column stalks. Tyres: When leaving the factory all MGBs originally fitted Pirelli Cinturato 165HR14 tyres (CA67).[9] MGB Roadster[edit] MGB Roadster 1974 MGB roadster gunmetal.jpg Overview Production 1962–1980 399,070 made Body and chassis Body style 2-door roadster Powertrain Engine 1,798 cc (1.8 l) B-Series I4 Dimensions Wheelbase 2,312 mm (91.0 in)[10] Length 3,886 mm (153.0 in) 4,019 mm (158.2 in) rubber bumper version[11] Width 1,524 mm (60.0 in)[11] Height 1,219 mm (48.0 in) 1,295 mm (51.0 in) rubber bumper version[11] The roadster was the first of the MGB range to be produced. The body was a pure two-seater but a small rear seat was a rare option at one point. By making better use of space the MGB was able to offer more passenger and luggage accommodation than the earlier MGA while being 3 inches (75 mm) shorter overall. The suspension was also softer, giving a smoother ride, and the larger engine gave a slightly higher top speed. The four-speed gearbox was an uprated version of the one used in the MGA with an optional (electrically activated) overdrive transmission. Wheel diameter dropped from 15 to 14 inches (360 mm). Mark II[edit] In late 1967, sufficient changes were introduced for the factory to define a Mark II model. Changes included synchromesh on all 4 gears with revised ratios, an optional Borg-Warner automatic gearbox (except in the US), a new rear axle and an alternator in place of the dynamo with a change to a negative earth system. To accommodate the new gearboxes there were significant changes to the sheet metal in the floorpan, and a new flat-topped transmission tunnel. All models are rear-wheel drive. To meet US safety regulations, later North American tourers got three windscreen wipers instead of just two (to sweep the required percentage of the glass), and also received a plastic and foam rubber covered safety dashboard, dubbed the Abingdon pillow. Other markets continued with the steel dashboard. Rubery Owen ROstyle wheels were introduced to replace the previous pressed steel versions in 1969 and reclining seats were standardized in 1970. 1971 also saw a new front grille, recessed, in black aluminium. The more traditional-looking polished grille returned in 1972 with a black honeycomb insert. 1970 saw split rear bumpers with the number-plate in between, 1971 returned to the earlier five-piece style. Mark III[edit] Further changes in 1972 brought about the Mark III. The main changes were to the interior with a new fascia. To meet impact regulations, 1974 US models saw the chrome bumper over-riders replaced with oversized rubber ones, nicknamed Sabrinas after the well-endowed British actress. In the second half of 1974 the chrome bumpers were replaced altogether, which are considered 1974.5 models. A new, steel-reinforced black rubber bumper at the front incorporated the grille area as well, giving a major restyling to the Bs nose, and a matching rear bumper completed the change. New US headlight height regulations also meant that the headlamps were now too low. Rather than redesign the front of the car, British Leyland raised the cars suspension by 1-inch (25 mm). This, in combination with the new, far heavier bumpers resulted in significantly poorer handling. For the 1975 model year only, the front anti-roll bar was deleted as a cost-saving measure (though still available as an option). The damage done by the British Leyland response to US legislation was partially alleviated by revisions to the suspension geometry in 1977, when a rear anti-roll bar was made standard equipment on all models. US emissions regulations also reduced horsepower. In March 1979 British Leyland started the production of black painted limited edition MGB roadsters for the US market, meant for a total of 500 examples. Due to a high demand of the limited edition model, production ended with 6682 examples. The United Kingdom received bronze painted roadsters and a silver GT model limited editions. The production run of homemarket limited edition MGBs was split between 421 roadsters and 579 GTs. The last MGB Roadster off the production line at Abingdon returned to Abingdon County Hall Museum on 1 December 2011 with the help of British Motor Heritage.[12] It was lifted up 30 feet through a first floor window of the Grade I listed building with inches to spare[13] and now forms part of the collection on display in the main gallery.[14] Work on a successor for the MGB had been undertaken as long ago as 1968, but British Leyland had pulled the plug on that project by the end of 1970.[15] When the Abingdon factory finally closed in the autumn of 1980, British Leyland did not replace it. MGB GT[edit] MGB GT MGB GT.JPG Overview Production 1965–1980 125,282 made Body and chassis Body style 2-door hatchback coupé Powertrain Engine 1,798 cc (1.8 l) I4 Dimensions Wheelbase 2,312 mm (91.0 in)[10] Length 3,886 mm (153.0 in) 4,019 mm (158.2 in) rubber bumper version[11] Width 1,524 mm (60.0 in) [11] Height 1,238 mm (48.7 in) 1,295 mm (51.0 in) rubber bumper version[11] The fixed-roof MGB GT was introduced in October 1965. Production continued until 1980, though export to the US ceased in 1974. The MGB GT sported a ground-breaking greenhouse designed by Pininfarina and launched the sporty hatchback style. By combining the sloping rear window with the rear deck lid, the B GT offered the utility of a station wagon while retaining the style and shape of a coupe. This new configuration was a 2+2 design with a right-angled rear bench seat and far more luggage space than in the roadster. Relatively few components differed, although the MGB GT did receive different suspension springs and anti-roll bars and a different windscreen which was more easily and inexpensively serviceable. Early prototypes such as the MGB Berlinette produced by the Belgian coach builder Jacques Coune utilized a raised windscreen in order to accommodate the fastback. Acceleration of the GT was slightly slower than that of the roadster due to its increased weight. Top speed improved by 5 mph (8 km/h) to 105 mph (170 km/h) due to better aerodynamics.
Posted on: Wed, 10 Dec 2014 01:56:45 +0000
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