The MG Story: The MGB

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The MG Story: The MGB



Without the MGA there could never have been an MGB. The "B" was a balanced, complete car, fully developed in the best way, and an ideal sports roadster of its type. It was never revolutionary in design, but rather another step forward along the path that was so successful with the "A." The step was a smart one from the makers with early MGB owners agreeing that it was the best engineered and put together MG ever seen.

The MGB would have been quite a bit different if it hadn't been for BMC's decision to bring out the Midget, the revised version. With the cheaper, simpler, smaller Midget on the market, the makers were able to ensure the "B" was a significant step up in comfort, size and price. However, the "B" was three cm’s shorter than its predecessor, in both wheelbase and overall length, and weighed only 23 kgs more.

Thornley and Enever really scored with the looks of the MGB, possibly with the advice of Pininfarina, consultants to BMC. The rather awkward front end of the MGA was followed by a design which was more successful than any other in the world at adding a sylish outline to this great car . It worked really well with the crisp edges of the recessed headlights. The grille looked good in its day but, like the flush, full fenders, it might have been too much for MG admirers if not for the MGA in between.

From the rear the MGB was bland to the point of being insipid but at least had the added bonus of some boot room, even though it was cramped due to the flat-placed spare tyre. There was more room for luggage behind the seats shielded by a curved windscreen. And in the doors were quarter-windows with roll-down glass. MG abandoned the side curtains which most accepted favourably.

Roomy Integral Construction

Abingdon rethought this new MG thoroughly, finding all kinds of new room inside. The feet were much less crowded and there was enough leg room even the tallest person. At one point the MG men considered moving the engine further forward to get even more room, but that would have meant giving up the rack-and-pinion steering, which they wisely decided was not a good idea. The space was gained through the changing of the body, to one with an integral frame. Gone was the deep, bridge-like frame of the "A," replaced by a sophisticated new body which used all the fixed parts of the body to help absorb the suspension stresses.

The main strength through the critical centre section was carried by the double-box-section sills under the wide doors, which were made of steel. The hood was the only aluminium part in this particular MG body. As they were in production for many years with this new body, MG tooled it elaborately, with front and rear chassis extensions welded into cross members below the stressed floor. On the original prototypes the main front cross member was welded into the body structure, but this caused too much noise to be heard so it became a separate sub frame, with rubber mounts. Another different body feature was a cowl inlet for fresh air - a welcome addition, but as for the heater system, its feeble output continued another MG tradition.

Suspension Refinements

The MG designers did not want to meddle with the successful formula. Of the MGA suspension. Chief Engineer Syd Enever evaluated independent rear suspension and favoured it because it eliminated axle tramp. But it was more expensive too and the average customer did not notice any improvement. Adopting the existing geometry, Enever and his men concentrated on giving the more civilized MGB a suppler ride. The springs were softened at all four corners. One leaf was removed from each rear spring, bringing the rate to 1768 kg/ m the MGA's 2232 Kg/m. At the front the coil springs were softened from 1786 to 1303 Kg/m for the first MGB's. Enever decided to keep the traditional lever-type shock absorbers throughout, thereby using a type of damper which has been replaced on most cars of that era by the more effective tubular design.

Since the TD, rack-and-pinion steering had been an MG trade­mark; the only change in the "B" was the adoption of a new tooth angle on both rack and pinion to reduce the amount of steering wheel kick induced by bumps in the road. Steering response remained excellent and was said to be as "practically as positive as that of a bicycle."

But the question remained about its overall quality. Steering effort required was extreme through tight corners, even with the very large standard steering wheel, and it also required much strength at lower speeds. But on the other hand the MGB was extremely stable at speed on a freeway. The springing changes improved the ride, as did a switch from 38cm to 35.5 cm wheels, both discs and knock-off wires being offered.

The MGB worked well on most brands and types of tyres with its simple suspension and balanced weight distribution. Radial ply tyres gave the best fuel consumption and very good handling as well. On icy roads studded tyres gave good traction but the front/rear ratio of stud numbers and locations needed close watching to keep the car from being unstable on dry roads.

Smaller wheels called for slightly smaller front brake discs, down in diameter to 27.3 cm to allow calliper clearance. With more performance than ever before, and more weight in the later GT version, the MGB placed more demands on its brakes than any other disc equipped MG. Front brake pad life ranges between 17,700 kms and 32,187 kms per set, with a median of 24,140 kms for fast road driving.

If you really wanted to use an MGB to its full capacity the optional harder brake pads from BMC or Raybestos or Mione should be fitted. One feature of the "B" that couldn’t change so easily was the handbrake, which was no longer of the racing fly-off release type.

More Displacement and Output

Amazingly improved performance for the MGB came out of the same basic B-type BMC engine that was introduced with the ZA Magnette. This unit traced its beginning back to the Austin A40, with a displacement of only 1200cc. In the A40 its bore was 65.5mm. In the MGB, introduced in July, 1962, the bore was a remarkable 80.3mm. Both engines had the same stroke: 88.9mm. The MGB's displacement came out to 1798cc, remarkably close to the size of the original 1925 MG, 1802cc. The 10.8 percent increase in engine size, held the original exterior dimensions,which needed even thinner iron sections and no water between the front and rear pairs of cylinders.

In compensation, holes were added for oil spray and more cooling lubricant on the undersides of the pistons. The oil has to be cooled in turn by a new front-mounted oil cooler that had been standard on exported MGB’s. Output of the expanded MGB was not spectacular-94bhp at 5500rpm - but the new engine showed a surprising willingness to rev, inherited from the MGA 1600 Mark II. The tach red line starts at 6000 but an early MGB will wind safely to 6800. More useful in everyday driving is the improved torque of the MGB, with a much fatter curve at low engine speeds, reaching its peak of 14.8 meter kgs at 3500 rpm. This is the part that really added to the performance.

In October 1964, the "B" engine was given two additional mains. Some tuners kept using the three-bearing block, which had less frictional drag, and the early five-bearing engines were also marked by pronounced vibration periods at 4000 and 5000rpm. Some slight power revisions came with this change, and also with the adoption for 1968 of air injection equipment to reduce exhaust pollution. After this the power rating of the Mark II MGB became 92bhp (down from a peak of 98bhp) at 5400rpm, with peak torque of 110 pound-feet at 3000rpm. Most MGB owners had problems with the exhaust system, often at intervals of 8,000 kms. After a while welding and clamping failed to do the job, and an early investment in a special exhaust system like the British Peco in the long run turned out to be a wise one.

Increased Range of Gearing

It was well for many years that the MGB engine was so flexible, because MG remained firm in its belief that first gear didn't have to be synchronized. The "B" gearbox was much improved, with nicer synch on the top three speeds. But first remained crash type, and second gear remained low so that owners unable to shift down adeptly to first could start away from rest in second. On the Mark II MGB a synchromesh first gear is at last provided, along with higher first and second gear ratios. With the smaller road wheels of the "B" the rear axle ratio was raised from 4.1 to 3.9 to one. Other lower ratios were also offered mainly for racing: 4.3, 4.55 and 4.88 to one.

Overdrive, available since January 1963 on the MGB provided another approach to the axle ratio selection problem. The unit, an electrically-operated Laycock de Normanville, provided an overdrive ratio of 0.802 to one. It operated only on third and top gears, with overdrive third being practically a duplicate of direct fourth gear. The overdrive option was highly valued by MGB owners for its ability to cut engine speed at cruise down from 4000+rpm to only 3300 or so. Clues to the provision of overdrive are a straight shift lever in place of a bent one, and the prefix "R" to the engine number. On the Mark II version of the MGB the staff from Abingdon went all the way toward American tastes in shifting with the additional option of an automatic box. It was the familiar Type 35 Borg­Warner three-speed with a torque converter, fitting neatly inside an enlarged transmission tunnel. The short lever control gave a positive hold for first and second gears, an aid to the sporty automatic driver.

Coupe Version: MGB/GT

The MGB/GT coupe, introduced in October 1965 was seen as the most civilised MG in history. Reviewed by the media and public alike it was seen as being quiet, smooth and a good looking car. It blended the sporty MGB lower body with a perfectly proportioned top that didn’t try to copy Jaguar or Corvette, but instead captured the crisp look of the Aston Martin coupes of the mid-Fifties. It was practical as well as attractive. The rear "door" was very handy, opening on a metre deep rear compartment. A tiny rear bench folded upward to provide temporary seating space. Tall windows had an open look and offered good visibility.

Added insulation accounted for part of the GT's 123 kg increase in weight, as well as its remarkably quiet interior. Much of the additional weight of the MGB/GT was toward the rear. The roadster had 47 percent of its weight on the rear wheels with the coupe having 49 percent. With the driver and a full tank of fuel, the GT was perfectly balanced at 50-50 front to rear. In view of this, the makers said that they had to start on the springing again. They put stiffer springs on the rear [which replaced the leaf removed from the MGA] which resulted in an increased oversteer. This resulted in an anti-roll bar on the front. The makers had to take some of the weight transfer from the rear and add it to the front.

They even had to stiffen the front springs. It did give a slightly harder ride due to the car being heavier. Most drivers weren't happy about the ride, finding the GT bouncy and prone to pitching. But the changes improved the handling, so much so that many preferred the coupe to the roadster. Both were wonderfully controllable and forgiving cars in the finest MG tradition. The coupe was summed up as "It's a very willing, rewarding car with a long-legged performance and an endearing character." BMC moved fast to adapt its cars to the U.S. safety regulations, fitting both versions of the MGB with new interior door handles and completely new dashboards, fully padded on the passenger's side. They were good-looking and certainly effective, though they unfortunately eliminated the glove box.

Smaller instruments and switches were grouped in a housing centred in front of the driver. Detailed problems have not been unknown to MGB owners, such as water leaks in the coupes and the roadsters top seams that tended to disintegrate after the first year and a half of due to weathering. There were minor problems in the biggest MG, which was a car that was capable of long and satisfying service. And in its era it managed to do so without costing an arm and a leg to buy or to use ... unlike many sports cars of its time. Sales of the MG were enormous giving it a ranking as the most successful MG in history.

Also see: MG Heritage | MG Performance Chart
1971 MG MGB
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