MG RV8 – Encyclopedia

27 Dec 2014 | Author: | Comments Off on MG RV8 – Encyclopedia


History [edit ]

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 MGB’s rival, the Triumph TR series. [ 2 ] 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’s performance was considered brisk at the time of its introduction, with a 0–60#160;mph (96#160;km/h) time of just over 11#160;seconds, aided by the relatively light weight of the car. Handling was one of the MGB’s strong points. The 3-bearing 1798#160;cc B-Series engine produced 95#160;hp (71#160;kW) at 5,400#160;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 1974, 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#160;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#160;mph (48#160;km/h) impact with an immovable barrier (200 ton). [ 3 ] [ 4 ]

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#160;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 all MGB is good with a peak of 110#160;lb·ft (150#160;N·m)Template:Convert/track/abbr/on Fuel consumption was around 25mpg [ 5 ]. 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#160;bhp (71#160;kW)Template:Convert/track/abbr/on at 5,500 rpm, with 105#160;lb·ft (142#160;N·m)Template:Convert/track/abbr/on 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#160;bhp (70#160;kW)Template:Convert/track/abbr/on ; by 1974 it was 87, with 103#160;lb·ft (140#160;N·m)Template:Convert/track/abbr/on torque; by 1975 it was 85 with 100#160;lb·ft (140#160;N·m)Template:Convert/track/abbr/on.

Some California specification cars produced only around 70#160;hp (52#160;kW)Template:Convert/track/abbr/on 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#160;mm)Template:Convert/track/adj/on SU carburettors. US spec cars from 1975 used a single Stromberg 1.75-inch (44#160;mm)Template:Convert/track/adj/on 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 electronic 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 [ 6 ] 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 but the overall ratio in third gear overdrive was roughly the same as fourth gear direct. Later cars allowed the overdrive to operate only in fourth gear.

The overdrive unit was engaged by a toggle switch located on the dash on 1963–1974 cars and on a gear lever mounted switch on later cars. Overdrives were fitted to less than 20% of all MGBs, making it a very desirable feature.

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 MGA’s 4.1 (or 4.3) to 3.9 to 1. (Compensating for the reduction from 15#160;inch to 14-inch (360#160;mm)Template:Convert/track/adj/on 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#160;mm)Template:Convert/track/adj/on 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. Script error

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). [ 7 ]

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