The Marque
“The world's best-selling sports car.”
A description that was accurate for most of the 1960s and 1970sThe MG factory at Abingdon produced sports cars from 1929 until British Leyland closed it in October 1980 — a decision that provoked widespread public outrage and a "Save Abingdon" campaign that ultimately failed. By the time the last MGB rolled off the line, the factory had produced 387,675 MGB roadsters, 125,597 MGB GTs, and 226,526 MG Midgets. The numbers matter: they are the reason parts remain available, specialists remain viable, and the cars remain affordable entry points to classic car ownership.
The MGB replaced the ageing MGA in 1962 with a monocoque body construction (replacing the MGA's separate chassis), an all-synchromesh gearbox, and the proven 1798cc B-series engine. It was modern where the MGA was traditional, and it sold accordingly. The MGB GT fastback coupe arrived in 1965, designed in collaboration with Pininfarina, and provided a more practical closed body with occasional rear seating. Optional overdrive was added in 1967 and became one of the most desirable features on the used market.
The Midget ran alongside the MGB throughout, sharing its factory and much of its mechanical DNA with the Austin-Healey Sprite. Early Midgets used Austin A-series engines in 948cc and 1098cc form; the definitive 1275cc version arrived in 1966 and remained until 1974, when British Leyland grafted in the Triumph Spitfire's 1493cc engine to meet emissions requirements. This final Midget is often overlooked but drives well with the correct 45 DCOE Weber fitted.
The community that has grown around these cars is one of the strongest in the classic world. The MG Owners Club, founded in 1973, is one of the UK's largest single-marque clubs. The MG Experience forum is the most active online resource. Abingdon Works — a term used affectionately by owners to mean the whole ecosystem of knowledge, parts, and community that surrounds Abingdon-built cars — remains a living thing four decades after the factory closed.
Model History
Three distinct models across nearly two decades of production. Know which car and which specification year you have before ordering anything structural — bumper-era differences affect more than cosmetics.
The core model. Monocoque construction, 1798cc B-series engine, four-speed all-synchromesh gearbox. Chrome bumper specification ran from 1962 to October 1974 — these are the more desirable cars, with lower ride height, genuine chrome trim, and the classic sports car profile. Rubber bumper specification ran from late 1974 to 1980, with raised suspension, polyurethane impact overriders, and revised front valance. Wire wheels were a popular optional extra throughout; rostyle steel wheels became the standard from the early 1970s. Overdrive (Laycock D-type) was available as an option from 1967 and fitted to most late cars as standard. The roadster is the more valuable and more sought-after of the two MGB body styles.
The fastback coupe body designed with Pininfarina input. Structurally stiffer than the roadster due to the fixed roof, with marginally better handling as a result. Rear occasional seating is genuinely usable for children or small adults. The GT hatchback provides useful boot space, making it a practical year-round classic. Same drivetrain as the roadster: 1798cc B-series, optional overdrive, same chrome/rubber bumper timeline. An MGC GT variant used the 2912cc six-cylinder C-series engine from 1967 to 1969 — a relatively rare and specialist car. A V8-engined GT (MGB GT V8, 1973–1976) used the Rover 3500cc V8 unit. GT body panels differ from the roadster from the A-post rearward — always specify your model.
The smaller companion to the MGB, sharing its factory and its design philosophy with the Austin-Healey Sprite. Early Mark I and II cars (1961–1966) used the A-series engine in 948cc and 1098cc form with a distinctive frogeye-influenced body. The Mark III (1966–1974) brought the 1275cc engine, round rear arches, and wind-up windows. The final Mark IV (1974–1979) used the 1493cc Triumph engine with a single Zenith-Stromberg carburettor — or, in restored form, a Weber 45 DCOE. Midget body parts differ from MGB in almost every dimension but the rust patterns are identical. Parts are slightly less widely available than MGB but remain well-supported by Moss Motors, Rimmer Bros, and dedicated Midget specialists.
Engine Variants
Two engine families cover the vast majority of MGBs and Midgets. Understanding which unit you have determines your parts sources and rebuild strategy.
B-Series 1798cc (MGB all years)
The B-series is a cast-iron pushrod unit designed by BMC in the early 1950s and continuously developed through the MGA and MGB years. In the MGB it displaces 1798cc with a bore of 80.26mm and stroke of 88.9mm. Early cars (1962–1971) produced around 95bhp through twin HS4 SU carburettors. Emissions regulations progressively reduced output to around 85bhp by the mid-1970s, with the final rubber bumper cars running a single HIF6 Stromberg or SU on US-specification cars.
The B-series is a robust and well-understood engine. The main wear items are the cylinder head (prone to cracking if overheated), the timing chain and tensioner, the main and big-end bearings, and the oil pump. A comprehensive rebuild kit covering pistons, rings, bearings, gaskets, timing chain, and water pump costs £250–£450 from Moss Motors, Rimmer Bros, or Leacy MG. The head should be pressure-tested for cracks before any rebuild — replacement reconditioned heads are available if cracked. The five main bearing engine introduced in 1964 (replacing the earlier three-bearing unit) is stronger; earlier three-bearing engines are more prone to bearing and crank issues under hard use.
A-Series 1275cc (Midget 1966–1974)
The definitive Midget engine. The 1275cc A-series with twin 1¼-inch SU HS2 carburettors produces 65bhp in standard form — a genuine performance unit in a car weighing under 700kg. The A-series is even simpler than the B-series and arguably easier to rebuild. Rebuild kits are available from Moss Motors, Rimmer Bros, and Austin specialists. The 1275cc head is prone to valve seat recession on unleaded fuel — hardened valve seat inserts should be fitted if the head is being rebuilt or replaced. An unleaded fuel conversion kit (hardened inserts plus a suitable lubricating oil additive) is strongly recommended for regular road use.
Triumph 1493cc (Midget Mark IV, 1974–1979)
Fitted to meet US emissions requirements when the 1275cc unit could not be sufficiently detuned without becoming unusable. The 1493cc Triumph Spitfire engine in standard Zenith-Stromberg form produces around 66bhp but has a flat torque curve compared with the 1275. Most owners fit a Weber 45 DCOE or twin SU HS2s for improved response. The Triumph engine requires Triumph-specific parts for the short block — do not assume A-series parts cross over. Triumph specialists and Rimmers Bros are good sources for 1493cc components.
Chrome vs Rubber Bumper Era
This is the single most important specification distinction when buying or restoring an MGB. The dividing line is October 1974.
| Specification | Chrome Bumper (1962–Oct 1974) | Rubber Bumper (Oct 1974–1980) |
|---|---|---|
| Ride Height | Standard / lower | 38mm higher (suspension raised) |
| Bumpers | Chrome steel overriders | Polyurethane impact absorbers |
| Front Valance | Simple curved panel | Extended integrated bumper/valance |
| Bonnet & Boot | Original pressed steel profile | Revised profile to suit bumpers |
| Handling | More sporting | Softer / more understeer |
| Weight (approx) | 890kg roadster | 960kg (added bumper mass) |
| Market value | 20–30% premium | Lower; often converted to chrome spec |
Chrome bumper conversion of a rubber bumper car is a well-documented and popular modification. The components required are: chrome front and rear bumpers with overriders, chrome bumper bonnet (the profile differs), chrome bumper rear boot lid, front and rear valances, and a suspension lowering kit (to restore the correct ride height). Total parts cost: £600–£1,200 depending on quality of chrome items. This conversion does not require any chassis modification and is reversible. Fitting time is typically one to two days for a competent home restorer.
Common Problems & Fixes
The MGB's most critical rust failure. Sills are structural — the body depends on them for rigidity. Outer sill rot exposes inner sill rot; by the time you can push a screwdriver through the outer, the inner structure is usually compromised. Repair requires removal of the A-post finisher, door aperture seals, and often the floor panels to access the inner sill properly. Repair sections and full sill sets are available from Moss Motors and Leacy MG. Do not patch over rotted sills with filler — this masks a structural failure. A proper sill restoration costs £400–£800 in parts; professional labour adds £600–£1,200.
MGB floor panels rust from the underside, accelerated by trapped moisture between the rubber mat and the panel. The footwells and gearbox tunnel edges are the primary failure points. Full floor pan repair sections are available from Moss Motors, Leacy MG, and Rimmer Bros. Replacement requires spot-weld removal of the old panel and MIG welding of the new section. POR-15 or similar encapsulant applied to the underside after repair significantly extends life. Budget £200–£400 in parts for a full floor replacement; professional welding labour adds considerably.
The Laycock D-type overdrive's most common failure mode is loss of hydraulic pressure due to a clogged strainer screen. Remove the sump plate, clean the strainer thoroughly, and check the oil. If pressure is restored, no further work is needed. The solenoid switch is the next failure point — test with a multimeter for continuity and replace if faulty (£25–£40). A failed uni-directional clutch requires a full overdrive rebuild (£400–£800 from a specialist). Non-overdrive cars can be converted using an overdrive gearbox from a donor car — a conversion that transforms long-distance driving.
Hunting idle, weak mixture, and flat spots on twin HS4 carburettors are almost always caused by: (1) air leaks at worn throttle spindles, (2) worn needle jets, (3) failed diaphragms in dampers, or (4) incorrect mixture/needle setting. Check for throttle spindle wear first — a worn spindle cannot be fixed by jetting. Rebuild kits covering diaphragm, needle valve, gaskets, and jets: £35–£65 per carburettor from Moss Motors or Rimmer Bros. SU Carburettor Technical Manual (available from MG Owners Club) covers all variants. Many owners fit a single HIF44 as a simplified alternative.
Characteristic by a clonk or click under acceleration and deceleration. The knock-on hub splines and/or wheel centre splines are worn. This is a safety issue — do not defer. Inspect hubs for radial movement when the car is on a lift. Replace worn hubs; replacement hubs are available from Moss Motors and Brown & Gammons. Rebuilt wire wheels are available from specialist rebuilders; new reproduction wheels from MG specialists. Regular spline greasing and correct hammer-tight fitting (clockwise on left, counter-clockwise on right) is essential for preventing future wear.
Chrome deteriorates from pitting through to base metal exposure and flaking. Rechroming original bumpers is possible (£180–£350 per bumper depending on extent of rot) but only cost-effective for presentable originals. Severely pitted chrome will show through any replate. New reproduction chrome bumpers are available from Moss Motors, Brown & Gammons, and British Motor Heritage for £120–£280 per bumper. Quality varies significantly between suppliers — Brown & Gammons is generally the most reliable source for correct-profile chrome items. Wire wheels and overriders can also be rechromed; specialist plating firms are available through the MG Owners Club.
The polyurethane impact absorbers on rubber bumper cars sag and deform over time due to UV degradation and the hydraulic damper units behind them collapsing. Replacement rubber bumper assemblies are available but expensive (£200–£400 front and rear). Most owners of rubber bumper cars elect to convert to chrome bumper specification instead — a conversion that is cheaper than replacing both rubber bumper assemblies with quality items and restores the car's original sporting character.
MGB roadster hood frames wear at the pivot points and header rail, producing a hood that won't close correctly, rattles at speed, or leaks at the windscreen. Frame pivot repair kits are available from Moss Motors and Rimmer Bros. A complete replacement hood assembly (frame plus hood cloth) costs £200–£450 depending on quality. Hood replacement is a half-day job with the correct tools and patience. The frame condition should be assessed before buying a hood cloth — fitting a new cloth to a worn frame is a false economy.
Lucas electrics on MGB are not inherently poor — they are 1960s engineering that has aged. Most problems are caused by corroded earth connections, cracked insulation, and failed switches rather than systemic design failure. The main areas: earth straps from body to chassis to engine (clean and check all), the fusebox contacts (clean with contact cleaner), the overdrive solenoid wiring, and the ignition switch contacts. A wiring loom replacement from Autosparks (UK) or British Wiring Inc (US) provides a complete harness to original specification for £400–£700. This eliminates accumulated bodge wiring at a stroke.
MGB rear leaf springs sag with age, reducing ride height at the rear and promoting understeer. The correct rear ride height is 13 inches from the ground to the centre of the rear wheel arch. New rear leaf springs from Moss Motors or Brown & Gammons cost £80–£150 per spring. Uprated springs for improved handling are available from Frontline Developments and other specialists. Spring replacement requires the rear axle to be lowered — a manageable home workshop job with a trolley jack and axle stands. Parabolic spring conversions offer improved ride quality over the original multi-leaf setup.
The B-series engine has several chronic leak points: the rocker cover gasket (a standard service item, £8–£15), the front timing cover oil seal, the rear crankshaft lip seal (the most awkward — requires gearbox removal), and the oil pump gasket. Rocker cover leaks feed directly onto the exhaust manifold and create the characteristic MGB smoke-and-steam show on startup. Replace the rocker cover gasket as a matter of routine. The timing cover and rear seal are worth addressing during any engine-out service. Genuine cork gaskets seal better than composite substitutes on the rocker cover — do not use RTV sealant in place of a proper gasket.
The A-posts (front door pillars) rust from inside the cavity, where the seal retainer channel traps water. The external panel may look presentable while the inner structure is heavily corroded. Probe carefully at the lower A-post and the sill-to-A-post junction. Repair sections are available but A-post restoration is intricate bodywork — it involves the door aperture geometry and must be done correctly to ensure the door fits and seals properly. A compromised A-post is often visible as a door that drops or doesn't close cleanly. Budget accordingly if A-post work is needed — professional bodywork here is money well spent.
Body Rust — Where to Look
The MGB's monocoque body means that rust in the wrong place is not a cosmetic problem — it is a structural one. Here are the areas that determine whether a car is a sound project or a money pit:
- Outer and inner sills: The most critical structural area. Test with a sharp probe at the centre of the outer sill and at the sill-to-A-post and sill-to-B-post junctions.
- Floor panels: Check from underneath. Look for soft spots, lifting seam sealer, and drain hole condition. The gearbox tunnel sides are a secondary failure point.
- A-posts (front door pillars): Probe the lower portion. Water ingress through the seal retainer channel causes hidden internal rot.
- Inner rear wings: Remove the rear quarter trim panels to inspect. Rust forms behind the wheel arch liners where mud accumulates.
- Rear spring hanger boxes: The rear chassis legs where they mount to the body can rot through, compromising rear suspension geometry.
- Chassis legs (front): The front suspension pick-up points on the monocoque. Check the outriggers and the area around the steering rack mounting.
- Rear valance: Traps mud above the exhaust pipe. Repair panels are inexpensive (£40–£80) but indicate a car that has been neglected underneath.
- Battery box (boot floor, roadster): Acid spillage from the battery corrodes the boot floor rapidly. Check carefully if the car has ever had a leaking battery.
OEM vs Reproduction Parts
The MGB aftermarket is enormous. This creates choice, but also risk: not all reproduction parts are equal, and some are significantly worse than original. The guidance below reflects community consensus built over decades.
| Component | Recommendation | Notes |
|---|---|---|
| Brake discs & pads | Quality brand (Mintex, EBC, Ferodo) | Avoid budget reproductions for safety-critical items |
| Wheel bearings | SKF, Timken, or equivalent | No-name bearings carry significant failure risk |
| SU carburettor rebuild kits | Genuine SU or Moss Motors kits | Cheap kits use inferior diaphragm material |
| Body panels | Heritage or Leacy MG quality tier | Budget panels have poor fit and thin steel |
| Chrome trim | Brown & Gammons or Moss Motors | Profile accuracy varies; buy from reputable source |
| Hood (roadster) | Black Label or premium aftermarket | Cheap hoods don't seal and look wrong |
| Engine gasket sets | Victor Reinz or Payen sets | Full sets from Moss or Rimmer Bros are reliable |
| Wire wheels | Rebuilt originals or Dayton reproductions | Rebuilt originals are stronger; Dayton widely used |
| Rubber seals (doors, windows) | Moss Motors or Rimmer Bros | Profile accuracy is critical for water exclusion |
| Ignition components | Lucas or Intermotor where available | Pattern ignition parts produce inconsistent results |
The heritage bodyshell programme is the ultimate OEM source for structural work. British Motor Heritage manufactures new MGB roadster and GT bodyshells to original specification. These are the correct choice for heavily corroded cars or concours builds.
Supplier Quick Reference
Parts availability for the MGB and Midget is excellent. The suppliers below cover the full range from common consumables to obsolete hard-to-find items.
| Supplier | Location | Strength | URL |
|---|---|---|---|
| Moss Motors Europe | Northampton, UK | Largest UK catalogue; everything from consumables to bodyshells | mossmotors.com |
| Moss Motors USA | Goleta, CA | Primary North American source; same catalogue depth as UK | mossmotors.com |
| Brown & Gammons | Baldock, Hertfordshire | Specialist's specialist — deep stock, accurate parts, knowledgeable staff | browns.co.uk |
| Leacy MG | West Midlands, UK | Strong on body panels, trim, and rubber; Heritage panels stocked | leacymg.com |
| Rimmer Bros | Lincoln, UK | Broad catalogue; strong on mechanical; fast shipping | rimmerbros.com |
| MG Owners Club Shop | Cambridge, UK | Consumables, books, club parts, and specialist sourcing | mgownersclub.co.uk |
| Victoria British | Lenexa, KS (USA) | North American supplier with good mechanical and trim range | victoriaBritish.com |
| British Parts Northwest | Portland, OR (USA) | Pacific Northwest specialist; ships across North America | britishpartsnw.com |
| British Motor Heritage | Faringdon, UK | Heritage bodyshells; original tooling manufacturer | bmh-ltd.com |
| Octagon Car Club (OCC) | UK (Club) | NOS and used parts through club spares scheme; members source for each other | octagonccarclub.co.uk |
| eBay UK / eBay US | Online | NOS, used, and new reproduction; search by BMC part number for best results | ebay.co.uk / ebay.com |
| Amazon | Online | Mechanical consumables, filters, gaskets at competitive prices | amazon.co.uk / amazon.com |
| RockAuto | Madison, WI (USA) | Mechanical items at trade prices; strong on B-series bearings, brake components | rockauto.com |
| Autosparks | UK | Wiring looms to original specification; essential for loom replacements | autosparks.co.uk |
| Frontline Developments | Devon, UK | Performance and handling upgrades; suspension and braking systems | frontline-mg.co.uk |
Restoration Budget Guide
MGB restoration cost depends almost entirely on the body condition of the starting car. A solid body with tired mechanicals is always a better investment than a tatty body with a rebuilt engine.
| Work Category | Parts Cost | Notes |
|---|---|---|
| Full sill restoration (both sides) | £400–£700 | Professional welding labour: £600–£1,200 additional |
| Floor pan replacement (full) | £200–£400 | Includes footwells and tunnel sections |
| B-series engine rebuild (standard) | £400–£700 | Pistons, rings, bearings, gaskets, timing chain, seals |
| Gearbox overhaul (incl. overdrive) | £300–£600 | Synchro rings, bearings, overdrive strainer & clutch |
| Chrome bumper conversion | £600–£1,200 | Bumpers, valances, bonnet, boot, lowering kit |
| Brake system refresh | £200–£400 | Discs, pads, wheel cylinders, master cylinder, flexi hoses |
| Interior retrim (roadster) | £400–£800 | Seat covers, carpet set, hood, tonneau cover |
| Chrome trim refresh | £300–£600 | Bumpers, overriders, grille, door handles |
| Heritage bodyshell (new) | £6,000–£8,000 | For severely corroded cars; includes all labour for rebuild |
| Full restoration (solid body) | £6,000–£14,000 total | Mechanical + cosmetic; excludes professional bodywork |
| Full restoration (corroded body) | £12,000–£22,000 total | Includes structural metalwork and professional bodyshop |
Budget guidance: The most common restoration mistake is spending £3,000–£5,000 on mechanical and cosmetic work before properly addressing the sills and floors. A beautiful engine and interior on a structurally compromised body is worth less than the sum of its parts — literally. Address structural metalwork first, safety systems second, mechanicals third, and cosmetics last. A car that drives well and is structurally sound on modest paint is more valuable and more enjoyable than an immaculate car that shakes and leaks.
Related CarSpanner guides: See the MGB Grey Door Brush Seals guide for detailed seal sourcing, the MGA Parts guide for earlier MG content, and the Safety Components guide for brake and steering part sourcing principles that apply directly to the MGB.
Community Resources
The MGB owner community is large, well-organised, and genuinely helpful. The resources below are the ones that consistently produce results.
Founded in 1973, the MGOC is one of the UK's largest single-marque clubs with over 10,000 members. Benefits include a specialist technical helpline, access to the MGOC spares scheme (which stocks items the commercial suppliers don't carry), the monthly magazine, and club events. The MGOC shop sells consumables, books, and club-sourced parts. Membership is strongly recommended for any serious MGB or Midget owner — the technical helpline alone is worth the subscription. mgownersclub.co.uk
The most active English-language MGB forum. Technical questions receive detailed responses from a community with deep collective knowledge. The technical archive contains solutions to almost every common problem. A search of MGExp before starting any repair or parts search will almost always surface directly relevant discussion. mgexp.com
The Octagon Car Club covers Abingdon-built cars broadly, including MGA, MGB, and Midget. The club spares scheme accesses NOS and used parts that have disappeared from commercial suppliers. Membership provides access to the classifieds and technical library. octagonccarclub.co.uk
The heritage bodyshell programme is a living resource for the most seriously corroded cars. BMH also produces the Official Heritage parts documentation — essential if you need to verify part numbers against the original factory workshop manual. bmh-ltd.com
Frequently Asked Questions
What is the difference between chrome bumper and rubber bumper MGB?
Chrome bumper MGBs were produced from 1962 to late 1974 and are the more desirable specification. They use traditional chrome overriders front and rear, sit lower on their suspension, and have a more sporting character. Rubber bumper MGBs were produced from late 1974 to 1980 to meet US federal impact regulations. Large polyurethane overriders added 38mm of ride height and approximately 68kg of extra weight, and the suspension was raised to compensate — a change that worsened handling noticeably. The conversion back to chrome bumper specification is popular, well-documented, and reversible.
Where is the worst rust on an MGB?
The sills are the most critical corrosion point. They are structural — the body's rigidity depends on intact sills. Probe the outer sill at the centre and at both post junctions. A screwdriver through the outer sill almost always means the inner structure is also compromised. After the sills: floor panels (rust from below), A-posts (rust from inside the cavity), inner rear wings, and rear spring hangers.
What engine does the MGB use?
All MGB roadsters and GTs use the 1798cc B-series engine. The Midget uses the A-series: 948cc and 1098cc in early cars, 1275cc from 1966 to 1974, and the Triumph 1493cc unit in the final Mark IV. Both B-series and A-series rebuild kits are readily available from Moss Motors, Rimmer Bros, and Leacy MG.
Is MGB overdrive worth having?
Yes. A working overdrive reduces engine speed by around 22% at cruising speed, improving economy and refinement significantly. The most common failure is a clogged hydraulic strainer screen — cleaning this often restores function without further work. Non-overdrive cars can be converted using a donor gearbox.
How do I fix MGB SU carburettor hunting?
Check for throttle spindle air leaks first — these cause hunting that no jetting adjustment will fix. Then check diaphragm condition, needle wear, and mixture setting. Full rebuild kits from Moss Motors or Rimmer Bros (£35–£65 per carburettor) cover the usual wear items. The SU Carburettor Technical Manual from the MG Owners Club is the definitive reference.
What are wire wheel spline problems and are they dangerous?
Wire wheel spline wear causes a clonk on acceleration and deceleration. It is a safety issue — heavily worn splines can allow a wheel to detach. Inspect hubs for radial movement with the car on a lift. Replace worn hubs; new hubs are available from Moss Motors and Brown & Gammons. Regular greasing and correct hammer-tight fitting reduces wear rate.
How much does an MGB restoration cost?
A solid body MGB restoration to good driving condition costs £6,000–£14,000 in parts and home labour. A seriously corroded car requiring professional bodywork costs £12,000–£22,000. The structural metalwork (sills and floors) is the dominant variable. Buy the best-bodied car you can find — savings on a cheap purchase are consumed by bodywork costs within months.
MGB GT vs Roadster — which should I buy?
The GT is more practical for year-round use: better weather protection, stiffer body, rear hatchback. The roadster is the purer sports car experience and commands a 20–30% market premium. For a first MGB or a year-round driver, the GT offers more car for less money. For summer driving and driving pleasure as the primary goal, the roadster.
Are Heritage bodyshells available for MGB?
Yes. British Motor Heritage produces new MGB roadster and GT bodyshells from original tooling, starting at £6,000–£8,000. These are the right choice for heavily corroded cars or concours restorations. For most projects, careful panel replacement on a sound original shell is more cost-effective.
What is the best forum for MGB and Midget advice?
The MG Experience (mgexp.com) is the most active and knowledgeable forum. Search the archive before posting — the answers to most common problems are already there in detail. The MG Owners Club technical helpline is invaluable for members. For buying advice and classifieds, the MGOC classified section and Pistonheads are both productive.
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