- The groups
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T-Series and Y Type XPAG/XPEG fours, 1936–55 · Magnette two unrelated saloons, 1953–68 · MGA, MGB, MGC the sports cars, 1955–80 · Midget A-series then Triumph, 1961–79 · MGF and MG TF mid-engined K-series, 1995–2011.
- XPAG and XPEG
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XPAG 1,250cc: TB, TC, TD, TD Mk II, TF 1250 and the whole Y Type range. XPEG 1,466cc: TF 1500 only, with siamesed bores — no water passage between cylinders. MPJG 1,292cc: MG TA only, and it shares nothing with the XPAG.
- B-series
- 1,489cc Magnette ZA and ZB, MGA 1500, Magnette Mk III · 1,588cc MGA 1600 · 1,622cc MGA 1600 Mk II, Magnette Mk IV · 1,798cc MGB and MGB GT. The same family runs through the Austin A50, A55 and A60, Morris Oxford, Riley and Wolseley, so ancillaries cross widely.
- A-series
- 948cc Midget Mk I · 1,098cc Midget Mk I late and Mk II, and the MG 1100 · 1,275cc Midget Mk III and MG 1300. But the 1100 and 1300 mount it transversely with the gearbox in the sump — only internals cross. Never fit an ADO16 clutch or gearbox part to a Midget.
- C-series
- The MGC’s 2,912cc is the seven-bearing redesign, shared with the Austin 3 Litre — not the four-bearing engine of the Austin-Healey 3000, A99 and A110.
- Rover V8
- MGB GT V8 3,528cc · RV8 3,946cc. Different capacities, and the RV8 is only about 5 per cent carry-over MGB parts.
- Brakes, at a glance
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T-Series: Lockheed hydraulic 9in drums, the whole series, with two leading shoes at the front from the TD. Y Type Lockheed 9in, twin leading shoe on the YB. Magnette Lockheed drums all round, every mark, no discs ever. MGA drums to chassis 68851, then 11in front discs. MGB 10.75in front discs and 10in rear drums throughout, Lockheed. MGC Girling with servo — does not cross with the MGB. Midget drums to October 1962, then front discs.
- Electrics
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The one change we can state as fact: the MGB Mk II of autumn 1967 went to negative earth with an alternator in place of the dynamo. For every other model, check your own car — polarity is not documented in a citable source and conversions are common.
- Sister marques
- The B-series cars share ancillaries with Austin, Morris, Riley and Wolseley; the Midget is the Austin-Healey Sprite to July 1971; the MG 1100 and 1300 are ADO16, so they sit with the Austin Morris 1100 1300 collection.