MGB

The youngest MGBs are now over 25 years old, and accordingly every car has a different history, with differing levels of usage, maintenance, and quality of repairs. This guide provides a background to the MGB, and covers some of the issues specific to MGBs that a prospective buyer should consider when viewing a car.

This information is provided in good faith as a general guide to purchasing an MGB. It covers common issues, but is not intended to be exhaustive, and buyers should exercise sound judgement when considering technical matters. It is strongly recommended that any car be professionally inspected prior to purchase

History

The MGB roadster was released in 1962, followed in 1965 by the MGBGT. A six cylinder version known as the MGC / MGCGT was launched in 1967, but ceased production after only two years. A V8 engined version, available in GT form only, was produced from 1973 - 1976. The MGB and MGBGT production ceased in late 1980.

While there were some changes to trim, both inside and out, the MGB remained substantially the same throughout its eighteen year production run. The drive train, suspension, steering and braking were not significantly changed during this period.

Refer to the timeline in Appendix 1 to see the changes in the MGB during its production run.

Which MGB to buy?

Roadster or GT?

The initial choice is whether to buy a roadster or a GT. There is relatively little performance difference between them, so this decision really comes down to personal preference.

Many owners now use their MGBs as hobby cars, and accordingly the roadster is the more popular and generally commands higher prices. It has the obvious appeal of a convertible during the summer months, but is more limited in storage space and the soft top takes longer to erect than on modern sports cars. A good quality soft top in good condition should be reasonably weather proof.

The Pininfarina-styled GT is the more practical car, and to some people, a better looking car. The enclosed roof does give it more of a “grand tourer” feel than the wind-in-the-hair roadster, and being a hardtop offers slightly more security when parked. And while it is a "2+2", the back seat is not roomy!

Chrome bumper or rubber bumper?

Rubber bumpers were fitted from the 1975 model year to meet US safety regulations, and were used on all MGBs (i.e. non-US also), to avoid making two different versions of the car.

While the rubber bumpers provide some protection against minor dings, they are quite heavy and thus have an effect on performance. Rubber bumper cars were also raised slightly to meet US bumper height regulations, which has a detrimental effect on handling. This can be corrected through after-market handling kits.

The later rubber bumper cars (1977-80) are better equipped inside, feature dual circuit brakes and slightly lighter steering thanks to changes in the gearing, which makes them a little easier to drive.

The chrome bumper cars have a more “classic” look about them, which is reflected in their higher prices. The earliest cars with the chrome grille (1962 - 1968) are perceived as the most desirable. However, they are more basic inside with non-reclining seats, a “pack-away” hood, non-synchromesh first gear, and they lack a brake servo.

As the years progressed, these items were gradually updated and accordingly, the “late chrome bumper” cars of 1973 - 1974 are generally perceived as runners up in the desirability stakes.

The interior and exterior trim levels changed during the period 1962 - 1974, with changes in seats, hood, wheels, grille and dashboard. However, the condition of a car is generally more important than these minor differences. Virtually any part can be interchanged between models, and improvements can easily be retro-fitted.

An overdrive gearbox reduces engine noise and improves fuel economy when travelling at motorway speeds. An overdrive gearbox can be retro-fitted to a non overdrive car, however it is not an inexpensive undertaking.

What to look for when buying

Mechanical

The MGB is a very conventionally engineered car, with tough and well-proven mechanical components. Accordingly, most problems tend to arise through normal wear and tear rather than any design weaknesses.

Engine

The standard MGB used the BMC “B Series” 4 cylinder engine, of cast iron construction with overhead valves, a capacity of 1798cc and a nominal power output of 95bhp. This engine had already been in production in 1500cc and 1600cc versions prior to being enlarged to 1800cc for the MGB. A number of minor changes were made to the engine during its period of production, however the list of items to look for is relatively similar for all versions.

The B Series is not a particularly quiet engine and there will always be an element of tappet noise, even on a good example. The oil pressure should read 50psi at 50mph in top gear as a minimum. Check for any obvious oil leaks, and that the engine runs at correct temperature; MGBs are not known for overheating, and the gauge should read below halfway in normal running. The usual checks should be made for blown head gaskets. The engine should not use any significant quantity of oil nor should there be any blue smoke. Wear or incorrect adjustment in the twin SU carburettors can cause rough running.

Parts for the B series are readily available, and rebuilding these engines is not difficult. If you find an otherwise sound car with minor engine problems, do not let this put you off.

Gearbox & Rear Axle

The MGB was originally equipped with a four speed gearbox with non-synchromesh first gear. An overdrive became an option in 1963. This gearbox was replaced with a new all synchromesh four speed gearbox in 1968. The first gear ratio was changed in 1974, and the following year overdrive became standard.

The gearboxes are relatively tough and with regular oil changes can do large mileages. The early gearboxes can often have weak synchromesh on second gear and may be slightly noisy. The later gearbox does not generally suffer any major problems and should be tight and quiet in operation. Ensure that the clutch is smooth and takes up correctly

The rear axle originally installed was of the “banjo” type, which was changed for the Salisbury “tube” type in 1965 on introduction of the BGT. Regular oil changes will ensure a long life for this unit and there are no particular problems with it. A slight clunking can indicate wear in the thrust washers, which is relatively simple to fix.

Suspension - Steering - Brakes

The suspension of the MGB was derived from that of the MGA, but the key difference is that the B has a one piece front cross-member to which all suspension and braking components are bolted, allowing it to be removed as one unit.

The front suspension is a coil spring layout, with unequal length wishbones. The upper part of the wishbone is formed by the lever arm shock absorber.

The rear suspension has a live axle with leaf springs and lever arm shock absorbers.

The suspension system does not have any major vices, being strong and reliable. However, any wear in the bushes, springs or shock absorbers will result in poor handling and ride.

There is a higher degree of body roll in the rubber bumper cars, but the suspension on all Bs should feel tight and precise with no rattles or knocks.

It is important to ensure that there is not too much movement in the kingpins, and that the lever arm shock absorbers are not leaking.

New suspension components are available, as well as uprated suspension bushes and springs, plus numerous suspension uprating kits that allow the fitment of telescopic shock absorbers. The suspension on an MGB is not particularly difficult to work on, and an overhaul is well within DIY abilities.

The braking system is a conventional setup, with 10.7 inch discs at the front and 10 inch drums at the rear. Braking performance is more than adequate for even spirited driving, and the usual limitation is tyre grip. Brake servos were introduced as an option on earlier cars and were standardised in 1974 - retro-fitting a servo is relatively simple, but note that a servo only reduces the pedal action required somewhat, and doesn't improve actual braking performance.

The brake master cylinder was changed to a dual circuit layout in 1976.

The braking system does not have any major faults, although the handbrake can take careful adjustment to ensure it is operating effectively, and often the grease nipple on the handbrake cable is forgotten. Other than this, the normal checks that apply to vehicle brakes should be made.

The MGB uses a cam gear rack and pinion steering system. The gearing of the system changed from 2.9 to 3.5 turns in 1975, at which time a collapsible steering column was also introduced. The steering is generally trouble free, but check it is nice and tight with less than an inch of free play in the universal joint, and that the rubber gaiters are in good order.

Note that some people fit larger wheels and/or tyres to a B, which can result in heavier steering – so check the wheel and tyre combination when you drive a car. Original 165-14 passenger tyres are now uncommon, so modern 175/75R14 or 185/70R14 tyres may be fitted.

Bodywork

The body is the most expensive area of the car to put right, and accordingly the condition of the bodywork is the most important consideration when buying an MGB.

The MGB was the first MG sports car of monocoque construction, i.e. a bodyshell without a separate chassis. The bodyshell was somewhat over-engineered, and is exceptionally strong and well constructed. However, rust prevention was not as advanced as it is today, and accordingly it is important to ensure the car you are viewing is structurally sound.

The key area to check for corrosion on an MGB is the sills. The sills run from the back of the front wheel arch to the start of the rear wheel arch and form the main structural component of the car, and accordingly are very important. The outer section of the sill that is visible from the exterior has within it a central membrane, with an inner box section inside that. You should ensure there is no corrosion visible inside, outside or underneath the car in the area of the sills. Note that sometimes minor rust bubbles visible at the front or back of the sill may simply be corrosion in the outer panels, which is not critical but should be attended to before it spreads. However, this often cannot be determined without expert scrutiny, so treat any visible sill rust with suspicion.

If complete sill replacement is needed, the work should be carried out by someone experienced in this job, as correct alignment is vital.

While you are inside the car checking sills, lift the carpets and ensure the floors are sound. Also lift the carpets at the back of the cabin to check for any corrosion. If possible, remove the battery covers to ensure that the battery boxes have not corroded - below the roadster rear floor, or under GT back seat. Until 1975, MGBs had twin six volt batteries, after which this changed to a single twelve volt battery and removal of the nearside battery box. For economic reasons, most earlier cars will by now have been converted to a single 12V battery.

At the front of the car, check the bonnet. Earlier MGBs had an alloy bonnet, which can be susceptible to dents. Also check the front valance for dings and minor corrosion.

Look for corrosion at the base of the front wings, in the seam where the wing joins the scuttle, and around the headlights. Minor corrosion can also occur where the side trim strips are held on to the wing. A useful check is to reach inside the inner wing near the back, where you will find a small ledge; the top of this ledge can gather road dirt and hence can corrode, so a check with your hand is worthwhile.

Moving back, check the base of the doors and underneath the doors for corrosion and ensure the drain holes in the door bottoms are clear and free of rust. Ensure the door fit is good and that the doors open and close easily. Looking at the rear wings, check the wheel arches carefully and run your hand inside the rear wheel arch rim to check for filler or rust. The seam at the top of the rear wing should also be checked.

At the rear of the car, check the boot floor for corrosion and also ensure there is no evidence of fuel leaks from the top of the fuel tank, which can corrode (look for fuel leaks or smells). Check the GT tailgate or roadster boot lid for corrosion - as with the bonnet, the boot lid on roadsters was originally aluminium and was then changed to steel.

All of the exterior trim should also be checked for damage, though replacement of these items is relatively simple and not particularly expensive.

Rust damage may be hidden through the use of body filler. If in any doubt, it is strongly recommended that specialist advice is sought regarding the condition of the bodywork.

Interior

The interior of MGBs is fairly simple and virtually any part is now available new. Most cars will by now have had some re-trim, so what you may see on a car may not be standard or original equipment. Some MGBs have had their dashboards significantly modified for extra instruments or switches, so check that what you are seeing is original (refer to our pictures section).

Make the usual checks for worn seats, carpets door trim etc. So a tired interior may be used as a price bargaining point, but should not put you off an otherwise sound car.

MGC / MGCGT and MGB GT V8

The MGC was in production from 1967 - 1969, and was essentially an MGB modified to take the Austin 3 litre “C Series” engine. Whilst the car was a fine tourer, it was not such an out and out sports car as the MGB and accordingly was not widely accepted. It is now a rare car and commands significantly higher prices than the MGB. Its main visual features are a bulged bonnet and 15 inch wheels.

In addition to the engine, the MGC also featured a different front suspension and rear axle, but is otherwise similar to the MGB, and most of the checks noted above apply. However, the rarity of the car is such that if you are looking to buy one you will not have a significant degree of choice. It is recommended that you consult one of the experts in the MGC Register for assistance and advice.

The MGB GT V8 was in production from 1973 - 1976 and featured the alloy Rover 3.5 litre V8 engine. Visually, the V8 has Dunlop composite steel/alloy rims and V8 badges. Other than the engine and minor gearbox and suspension changes, it was virtually identical to the MGB. The engine is not a significant concern in these cars as the Rover V8 is a well proven and reliable engine, though it does require regular oil changes and the use of correct antifreeze to prevent corrosion. Other than the engine, check these cars as for a standard MGB.

Note that a number of MGBs and GTs have been converted to take the Rover V8 engine, and this continues to be a popular conversion. If you are viewing a car that has been converted, ensure you sight the vehicle's LTSA Compliance Certificate, and possibly consider an engineer's inspection to ascertain the quality of the conversion work.

Left Hand Drive Cars

The MGB was an extremely popular car in America, and accordingly the majority of production was sent to the USA. A number of these cars have since found their way to NZ, some of which have been converted to right hand drive. From the late 1960s, MGBs made for the US market had ongoing changes to meet US emission and safety regulations. This resulted in different interior and exterior trim, and most importantly, emission control systems that gradually reduced power. The later rubber bumper cars had a single Stromberg carburettor to replace the twin SUs, resulting in a significant performance reduction. All of these items can be removed, but when considering an ex-US car it is worth finding out which of these emission features are still fitted.

Conclusion

The MGB was in production for 18 years, during which time over 500,000 were produced. It remains a popular car and is the most numerous model in the MG Car Club. It is a relatively simple and DIY friendly car with excellent parts availability, and not difficult for a home mechanic to maintain. However, it is important to purchase the right car to start with - if you are looking for an MGB, you are encouraged to talk to existing owners and/or come to an MGCC event to look at a variety of cars. This will give you an idea of the differences between the variants, and help you to decide which would suit you best. Also, talk to some of the MG specialists in business. There are many good cars out there, but they can take a bit of finding!

Appendix

Timeline of changes

Year Event
1962 MGB Roadster commences production.
1964 Engine changed from three to five main bearing crankshaft.
1965 “Banjo” type rear axle replaced by stronger Salisbury “tube” type axle.
1968 Mark 2 models introduced, with new all synchromesh gearbox, optional automatic gearbox, negative earth electrical system, optional brake servo.
1969 “Recessed” type front grille introduced, along with “Rostyle” wheels, new reclining seats (now with vinyl rather than leather), new steering wheel and switchgear, new badges.
Boot lid changed from aluminium to steel.
1971 Further changes to switchgear and minor controls, new “Michelotti” folding hood introduced, tinted glass standard on GT’s.
1972 Dashboard revised with face level vents, new switchgear, centre console with new astray and armrest.
1973 New “honeycomb” style of front grille, new steering wheel, further changes to switchgear, vinyl seats replaced with velour, heated rear window standard on GT’s.
1974 Automatic gearbox discontinued, brake servo standard, further switchgear changes.
1975 Rubber bumpers introduced, collapsible steering column, suspension height raised and minor changes to springs and antiroll bars, new instrument binnacle.
Limited edition of 750 “Jubilee” BGT’s introduced.
1977 New dashboard, instruments, switchgear and steering wheel, electric engine fans introduced, rear anti roll bars in, dual;
1980 Production of MGB and MGB GT ceases.
MoST Content Management V3.0.6241