MGB Vehicle Information

CHASSIS (CAR) NUMBER, VIN & MAJOR UNIT SERIAL NUMBERS
The following illustrations show where the various identification/serial numbers are located on the MGB and MGB GT:

MGB ROADSTER 1962-1980
3 Synchro (‘Mk I’), 1963 to 1967 Model Years
GHN3-101 to 48766 (Jun. ‘62 to Oct. ‘64): 3 main bearing engine with dynamo, positive earth, 3 synchromesh gearbox. GHN3-48767 to 138400 (Oct. ‘64 to Oct. ‘67): 5 main bearing engine with dynamo, positive earth, 3 synchromesh manual gearbox.

4 Synchro (‘Mk II’), 1968 to 1980 Model Years
GHN4-138401 to 187209 (Nov. ‘67 to Oct. ‘69): 5 main bearing engine with alternator, negative earth, 4 synchromesh manual gearbox or automatic gearbox, last cars with chrome grille, last cars with BMC type interior trim with leather seats. GHN5-187210 to 219000 (Oct. ‘69 to Aug. ‘70): Black recessed grille, first cars with ‘Leylandised’ vinyl interior trim, last cars with packaway hood or deluxe folding (grey frame) hood. GHN5-219001 to 258000 (Aug. ‘70 to Aug. ‘71): Black recessed grille, last cars with 18G series engines, first cars with folding (black frame) hood. GHN5-258001 to 294250 (Aug. ‘71 to Aug. ‘72): Black recessed grille, first cars with 18V series engines, first cars with centre console with armrest. GHN5-294251 to 360300 (Aug. ‘72 to Sep. ‘74): Chrome/black honeycombe grille, first cars with cooling slots in front valance, last cars with chrome bumpers, last cars with overdrive switch on fascia. GHN5-360301 to 410000 (Sep. ‘74 to Jun. ‘76): First cars with rubber bumpers, overdrive switch on column stalk, last cars with mechanical radiator fan. GHN5-410001 to 501000 (Jun. ‘76 to Jun. ‘79): Overdrive switch on gear lever, first cars with electric radiator fan, commonly called ‘September 1976 on’ models (although the first car was built in June, the model was launched in September), last cars with traditional chassis numbers. GV_DJ_AG-501001 to 523001 (Jun. ‘79 to Oct. ‘80): Cars with new international VIN (vehicle identification number) type serial number

MGB GT 1965-1980
3 Synchro (‘Mk I’), 1965 to 1967 Model Years
GHD3-71933 to 139470 (Sep. ‘65 to Oct. ‘67): 5 main bearing engine with dynamo, positive earth, 3 synchromesh manual gearbox

4 Synchro (‘Mk II’), 1968 to 1980 Model Years
GHD4-139471 to 187840 (Nov. ‘67 to Sep. ‘69): 5 main bearing engine with alternator, negative earth, 4 synchromesh manual gearbox or automatic gearbox, last cars with chrome grille, last cars with BMC type interior trim with leather seats. GHD5-187841 to 219000 (Sep. ‘69 to Aug. ‘70): Black recessed grille, first cars with ‘Leylandised’ vinyl interior trim, horn push on column stalk. GHD5-219002 to 258003 (Aug. ‘70 to Aug. ‘71): Black recessed grille, last cars with 18G series engines, horn push back on steering wheel. GHD5-258004 to 296000 (Aug. ‘71 to Aug. ‘72): Black recessed grille, first cars with 18V series engines, first cars with centre console with armrest. GHD5-296001 to 361000 (Aug. ‘72 to Sep. ‘74): Chrome/black honeycombe grille, first cars with cooling slots in front valance, last cars with chrome bumpers, last cars with overdrive switch on fascia. GHD5-361001 to 410350 (Sep. ‘74 to Jun. ‘76): First cars with rubber bumpers, overdrive switch on column stalk, last cars with mechanical radiator fan. GHD5-410351 to 501035 (Jun. ‘76 to Jun. ‘79): Overdrive switch on gear lever, first cars with electric radiator fan, commonly called ‘September 1976 on’ models (although the first car was built in June, the model was launched in September), last cars with traditional chassis numbers. GV_EJ_AG-501036 to 523002 (Jun. ‘79 to Oct. ‘80): Cars with new international VIN (vehicle identification number) type serial number

MGB GT V8 1972-1976
GD2D1-101 to 2100 (Dec. ‘72 to Sep. ‘74): Chrome bumper models. GD2D1-2101 to 2903 (Sep. ‘74 to Jul. ‘76): Rubber bumper models

VEHICLE IDENTIFICATION
To ensure the parts that you order are correct for your MGB or MGB GT, you will need to know most importantly the chassis number (models up to 1979) or VIN (vehicle Identification Number, 1980 models only). Additionally when ordering engine parts you will also need to know the engine number. Gearbox, overdrive and axle numbers may be required to order parts for those major units.

Chassis (Car) Number
Chassis number prefixes are as follows:
GHN3 MGB Roadster, 3 synchromesh, 1962-67
GHN4 MGB Roadster, 4 synchromesh, 1967-69
GHN5 MGB Roadster, 4 synchromesh, 1969-79
GHD3 MGB GT (4 cyl), 3 synchromesh, 1965-67
GHD4 MGB GT (4 cyl), 4 synchromesh, 1967-69
GHD5 MGB GT (4 cyl), 4 synchromesh, 1969-79
GD2D1 MGB GT V8, 1972-76

VIN (Vehicle Identification Number)
The last six characters of the VIN are the serial number of your car. However, the VIN also provides you with considerably more useful information, most importantly the model year of your car (most changes in production relate to model years). The complete VIN can be broken down thus:

First character	G = MG marque
Second character	V = MGB model range
Third Character	A = UK spec. (Roadster)
	G = UK spec. (GT)
	J = Japan spec
	L = Canada spec.
	V = USA Federal spec.
	Z = USA California spec.
Fourth Character	D = Roadster body
	E = GT body
Fifth Character	J = 1800cc B Series engine
Sixth Character	1 = RHD steering, manual gearbox
	2 = LHD steering, manual gearbox
Seventh Character	A = 1980 model year
Eighth Character	G = Abingdon plant (MG factory)
Ninth to Fourteenth	999999 = serial number Characters

Example: A car showing GVGEJ1AG 501036 is - MG/MGB/UK spec. (GT)/GT body/1800cc B Series engine/RHD steering, manual gearbox/1980 model year/Abingdon plant (MG factory)/serial no. 501036

Engine No., 18G Series, 4 Cylinder Engine 1962-71
The engine number will tell you far more than just the serial number of your engine:

First prefix	18 = 1800cc
Second prefix	G = 3 bearing crank, open crankcase breathing
	GA = 3 bearing crank, closed circuit breathing
	GB = 5 bearing crank, closed circuit breathing, dynamo
	GD = 5 bearing crank, closed circuit breathing, alternator
	GG = 5 bearing crank, carb feed breathing circuit, alternator
	GF = USA/Canada only
	GH to GK = USA/Canada only
Third prefix (optional)	R = Overdrive
Fourth prefix	U = 3 synchro
	We = 4 synchro
	Rc = automatic
Fifth prefix	H = High compression
	L = Low compression
Remaining Digits	Serial number

Example: An engine showing 18GD R We H 6001 is - 1800cc/5 bearing crank, closed circuit breathing, alternator/overdrive/4 synchro/high compression/serial no. 6001

Engine No., 18V Series, 4 Cylinder Engine 1971-80

First prefix	18V = 1800cc, in-line
Second prefix	581F = Twin HS4 carbs, non-overdrive, 1971-73
	581Y = Twin HIF4 carbs, non-overdrive, export, 1971-73
	582F = Twin HS4 carbs, overdrive, 1971-73
	582Y = Twin HIF4 carbs, overdrive,export, 1971-73
	583F = Twin HS4 carbs, auto
	583Y = Twin HIF4 carbs, auto, export, 1971-
	779F = Twin HIF4 carbs, non-overdrive, 1974
	780F = Twin HIF4 carbs, overdrive, 1974
	846F = Twin HIF4 carbs, non- overdrive, rubber bumper
	847F = Twin HIF4 carbs, overdrive, rubber bumper
	584Z to 673Z = USA/Canada only
	836Z to 837Z = USA/Canada only
	797AE to 893AE = USA/Canada/Japan only
Third prefix	H = High compression
	L = Low compression
Remaining Digits	Serial number

Example: An engine showing 18V 847F H 40101 is - 1800cc, in-line/twin HIF4 carbs, overdrive, rubber bumper/high compression/serial no. 40101

Engine No., 486 Series, V8 Engine 1972-76

First prefix	486 = 3500cc, 8.25:1 compression ratio, MGB installation (rear mounted HIF6 carbs, remote oil filter head)
Fourth to Eighth Digits	Serial number

Example: An engine showing 48601301 is -3500cc, 8.25:1 compression ratio, MGB installation/serial no. 01301

MGB & MGB GT 1962-80
BMC’s Sports Car for the 1960s that Just Kept Going
Please forgive the author for pointing this out, but you have to be well into middle age now to remember a time when you didn’t see at least a smattering of MGBs turn up at any motoring event you chose to attend.

Now, for what has seemed like forever, the MGB has flown the flag as the iconic Classic British Sports Car. Then, for what seemed like forever, it ruled supreme as the world’s most numerous sports car, a title it only eventually lost to Mazda’s MX5 some dozen years or so after its 18 year production life ended in 1980. To this day, one fifth of all the half million MGBs ever built are still around, an unmatched survival rate for a car built in that sort of volume.

At different times during its production life the MGB also spawned the outwardly similar 6 cylinder MGC and the sublimely entertaining yet still practical MGB GT V8. Thanks to British Motor Heritage, in 1989 (that is, 9 years after the last MGB was completed and the MG factory closed) the MGB bodyshell came back into production, ensuring that as many MGBs as possible would continue to survive well into the next century. This new MGB bodyshell in turn formed the basis of the MG RV8, a new limited edition MG roadster brought about by Rover Group in the early 1990s to pave the way for the MGF and the return of new MG sports cars.

The MGB proved to be a much loved and long lived car, building up from the start a devoted following which is still as strong today as it was all those years ago. It was also a pretty basic, moderately robust, moderately performing, very forgiving, inexpensive (to start off with, anyway) car that cleverly continued MG’s strategy of inviting the masses to safely and affordably experience the fun of being in a sports car. A simple formula that was bang-on target, especially in MG’s biggest market place, the United States.

The 3 Synchro MGB: the MGA Replacement
The MGB’s predecessor, the MGA, had at last modernised the image of MG in the mid-1950s, its fully enclothed bodywork contrasting sharply with the pre-war styled square-rigger, ash-framed bodies of the previous MG T Types. The T Types had won and the MGA had kept the hearts of sports car lovers around the world, the MGA going on to become MG’s first really big seller at over 100,000 cars built. Continuing this success story would take skill and a fine understanding of what sports car customers wanted.

The MGB Roadster of 1962 would hit the nail right on the head. Intended to be MG’s car through the 1960s it was modern in style and line. Modernity continued under the skin because the MGB had a monocoque (self-supporting, rigid bodyshell) structure, thus departing from the T Type and MGA’s by now old school body-on-chassis construction.

The designers and engineers didn’t sweep aside all that had gone before, though. The MGA’s greatest forte was its exceptionally sweet handling, as anyone who has driven one will testify: rewarding for the more experienced driver who liked to push on yet benign and safe for the novice, while still managing to be entertaining for both. The MGB’s handling manners were to be as close to the MGA’s as possible, despite the radically different construction methods between the two designs. To ensure this it inherited MGA suspension, steering and weight distribution that were only altered where necessary (in fact many components of the MGB’s front and rear suspension go right back, unaltered, not only to the MGA but even further back to the T Types!).

The fact that through very careful suspension tuning and spring rate selection the MGB had a softer, much more comfortable ride than the MGA yet still achieved such lovely handling was a master stroke and won over many new customers to sports car driving. It also ensured that, more than with any other sports car of the time, the MGB could be enjoyed rather than endured as an everyday car on the one hand yet on the other hand could still be used effectively (and as it turned out, very successfully) with the minimum of serious modification in sporting competitions and racing.

The gearbox would be a mildly modified version of the MGA’s, still with synchromesh on 2nd, 3rd and 4th gears only (hence the early MGB’s colloquial name of ‘3 Synchro’), but unlike the MGA or other previous MGs there would be the desirable option of a Laycock D Type overdrive unit to usefully increase the transmission’s available ratios and the car’s driving flexibility. The MGA’s ‘banjo’ rear axle was used virtually unchanged.

The engine in the MGB could have been a very different matter. Lift the bonnet and look at the wide, only partly utilised space in the engine bay and you might conclude that the MGB was designed with a different shape of engine in mind. In fact, a stillborn V4 configuration engine had been seriously considered, but in the end the BMC B Series in-line 4 cylinder that had served well in the MGA was used (however the wide engine bay would greatly help engineers some years later when Rover’s V8 unit was squeezed in to create the MGB GT V8). To compensate for the increased weight of the MGB, the engine was increased in size (and therefore power) from the last MGA model’s 1622cc up to 1798cc.

Other aspects of the MGA’s B Series engine made it through unchanged to the early MGBs (like the geared drive for the mechanical rev counter and the 3 main bearing crankshaft), though over the years regular improvements brought about by technical progress or regulations imposed on the car meant that later MGB engines would share the familiar B Series silhouette and layout with MGA engines but almost every component would actually be different to a lesser or greater extent.

Enter the MGB GT
The 3 Synchro MGB (officially referred to as the ‘Mk I’ but these days rarely called that by enthusiasts) would be built between 1962 and 1967. During that time it was subject to many changes and improvements: overriders and other options were made standard fitment in 1963, new door mechanisms, fuel tank and an electric rev counter arrived in 1964, a tube type Salisbury rear axle replaced the MGA type banjo axle in progressively between 1965 and 1967, reversing lights came in for 1966 and so on. The biggest change however came in 1965 with the introduction of the MGB GT.

A hard top had been available as an accessory for the MGB Roadster for a while when a Belgian coachbuilder came up with a very pretty fastback conversion of the MGB in 1963, called the Berlinette. Always rare and valuable, this attractive car was destined to be eclipsed by MG’s own three door fastback, the MGB GT.

Launched in 1965 and featuring a roof and associated elements seamlessly styled into the MGB’s lines by Italian styling house Pininfarina, the MGB GT was arguably not as pretty as the Berlinette but far better proportioned and styled overall and had the added very practical bonus of a tailgate. In America, the MGB Roadster would always outsell the GT, but in the UK and most other major markets the GT quickly outsold its soft top sibling and continued to do so thereafter.

The 4 Synchro Mk II
In late 1967 the MGB & MGB GT Mk II were introduced. The big news for the Mk II was made by the transmission changes. Now an automatic MGB could be had, which used Borg Warner’s robust and basically refined Type 35 transmission - however it would never sell in big numbers and was dropped from the range by 1974. Manual cars at last received a new gearbox with synchromesh on all four forward speeds (hence the ‘4 Synchro’ moniker) and the overdrive, still an option, changed to the Laycock LH Type. The manual gearbox was developed alongside a very similar one for the new, bigger engined MGC and Austin 3 Litre models and as a result was markedly stronger than the old 3 Synchro ‘box.

Other Mk II changes included negative earth electrics and an alternator as standard, plus new door mechanisms - again. Otherwise things were much as per the previous year, except for USA-bound cars which received the ‘Abingdon Pillow’ safety dashboard and dual circuit brakes; these would be just the first of many special safety items demanded by the US market throughout the rest of the MGB’s production life.

British Leyland and All That
While MGB production was progressing through the 1960s, big reorganisations were taking place in the British motor industry which would have far reaching effects on the car. MG’s parent company, the British Motor Corporation (BMC), merged with Jaguar to form British Motor Holdings (BMH) at the end of 1966 and in early 1968 the short-lived BMH in turn merged with the Leyland Motor Corporation, owners of Triumph and Rover, to form the British Leyland Motor Corporation (BLMC, later just British Leyland or ‘BL’).

The trials, tribulations and ultimately the failure followed by nationalisation of British Leyland are well documented and discussed elsewhere, so it’s sufficient here to simply state that because of the company’s woes the funds necessary to develop new models were increasingly hard to come by and mainstream saloon projects for Austin and Morris soaked up nearly all of the little money that was available at the time. For the MGB a progression of light and inexpensive facelifts on the outside and trim material changes on the inside would have to do for now, in the hope of keeping the car selling in reasonable numbers for as long as it took until funds for a replacement model became available.

The MGB GT V8
A small but very bright ray of sunshine shone from MG in 1973 when the MGB GT V8 was introduced. As previously mentioned, the engine bay seemed perfectly sculpted to accept a Vee configuration engine and with Rover now in the same organisation there was an opportunity to develop at low cost an MGB fitted with Rover’s powerful, light alloy V8. The MGB GT V8 (always the GT bodystyle was used) was fast, powerful, loaded with torque and because the engine was so light despite its size, the MGB’s legendary handling was preserved as well.

It was the perfect MGB, except... MG couldn’t get hold of enough engines from Rover to build the cars and when they did build them, BL policy dictated that they would be priced so that they didn’t torpedo the sales of Triumph models of similar performance. Which meant that the MGB GT V8 cost far too much to buy. Then the Arab oil crisis of late 1973 quadrupled the price of petrol overnight, ensuring very few people could afford to run a car with a thirsty engine, as Rover’s V8 was perceived to be. When it could have and should have hugely bolstered MG’s sales figures and image, the MGB GT V8 became instead a minor sales curiosity, limping along for two and a half years in the showrooms and selling just 2600 cars. Today of course the story is different and the MGB GT V8 is very highly valued and revered, as it always should have been.

The Rubber Bumper Models
MG continued to wait for BL’s financial health to improve sufficiently to allow the development of a replacement for the MGB (in the end the wait would be in vain, the factory closing at the end of MGB production in 1980). Meanwhile the 4 cylinder MGB carried on in production through the mid and later 1970s, seemingly becoming more and more an anachronism. The grafting on of rubber bumpers and the raising of the MGB’s ride height (thus compromising that lovely handling) to meet forthcoming safety legislation in the middle of the decade had seemed for a while to be the last straw but amazingly the car kept on selling despite these apparent aesthetic and dynamic handicaps, albeit in steadily declining numbers.

Actually, the character of the MGB changed as it got older but critics at the time didn’t see any of the positive aspects of the character change; they just saw what looked like a sports car long past its sell-by date with middle age spread and less than sports carlike performance that simply shouldn’t be on sale any more. In many ways they were right, too: remember the first Volkswagen Golf GTIs were on sale a year or two before the MGB ceased production and were available at a similar showroom price.

However, the passage of time has mellowed those critics’ comments and allowed the rubber bumper MGB to be viewed in a much more favourable light. It’s now very apparent that the rubber bumper MGB is a little less of a sports car and more of a relaxed tourer with an endearingly classic retro edge to it - and actually it’s pretty good at the job of being a tourer, too. Even those rubber bumpers themselves now have their admirers! A late 1970s MGB or MGB GT with dual circuit brakes, direct acting servo, bullet-proof gearbox and overdrive, more modern switches and controls, halogen headlamps and electric radiator fan makes for a very easy to use, reliable and practical classic that can still - some 50-odd years after the MGB was first introduced - be treated as enjoyable and safe everyday transport.