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MOTRS

MGB GT

1965-1980 / Coupe / United Kingdom

Photo: Photo by Calreyn88 / Wikimedia Commons CC BY-SA 4.0

// THE STORY

The MGB GT took the roadster platform and added a Pininfarina-designed fastback body that many consider the better-looking car. The fixed roof added rigidity to the structure, improving handling, and the hatchback gave it genuine practicality. You could drive to a club event, carry your tools, and still enjoy the same B-series engine and precise handling as the roadster.

The GT has always been the more affordable MGB, partly because open-top cars carry a premium and partly because the GT was produced in smaller numbers. This makes it arguably the better value proposition for someone who wants to drive their classic regularly rather than just on sunny weekends. In Australia, the GT is popular for touring and regularity events where its comfort and luggage space are genuine advantages. Chrome-bumper GTs in good condition are becoming harder to find and prices are rising accordingly.

// SPECS
Body Coupe
Engine 1.8L Inline-4
Country United Kingdom
Production 1965-1980
Units Built 523,836

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// KNOWN ISSUES

What to watch for.

All 18 issues

Sill Corrosion (Inner and Outer)

Minor
Body and Structure
What happens

The outer sill skin bubbles, softens, and eventually perforates. In advanced cases, the outer sill crumbles when prodded. The inner sill -- the structural member -- rots from inside the box section and loses its load-bearing capacity.

Why it happens

The sills are box-section steel with drain holes at the bottom. These holes block with dirt and underseal, trapping water inside the cavity. Corrosion works from inside out, so by the time you see exterior rust, the inner sill may be compromised. The sills are structural -- they carry bending loads and support the door hinges.

How to fix it

Replace both inner and outer sill sections. This requires stripping the car to bare metal in the sill area, cutting out the corroded metal, and welding new panels. Quality repair panels are readily available from Moss Motors, British Motor Heritage, and others. Cost: $1,500--3,000 per side for professional work. DIY is possible but requires competent welding skills.

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Floor Pan Corrosion

Critical
Body and Structure
What happens

Soft or perforated floor pans, particularly in the footwells and under the seats. Wet carpet is a telltale sign. In severe cases, you can see the road through the floor.

Why it happens

Water enters through deteriorated door seals, windscreen seals, and from below via road spray. Carpet retains moisture against the metal. The floor pans are thin and have minimal factory corrosion protection.

How to fix it

Repair sections are available for all floor areas. Weld in new metal. Cost: $500--1,500 per section depending on extent.

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A-Post Corrosion

Minor
Body and Structure
What happens

Rust at the base of the windscreen pillars where they meet the scuttle panel. This area can be invisible until advanced.

Why it happens

Water runs down the windscreen surround and collects at the base of the A-post. The double-skinned construction traps moisture.

How to fix it

Cut out and fabricate new sections. This is skilled work that requires correct jigging. Cost: $1,500--3,000 for professional repair.

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Door Skin Corrosion

Minor
Body and Structure
What happens

Rust along the bottom edge of each door, working upward from the inside.

Why it happens

Drain holes in the door bottoms block, trapping water inside the door shell. The steel corrodes from inside out.

How to fix it

Replacement door skins are available. The skin is peeled off the frame, the frame is treated, and a new skin is crimped on. Cost: $300--600 per door.

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Rear Spring Hanger Corrosion

Minor
Body and Structure
What happens

The mounting points for the leaf spring rear suspension corrode, crack, or tear away from the body.

Why it happens

Road spray and mud accumulate around the spring hangers. The metal thins and weakens under the constant load of the spring.

How to fix it

New spring hanger assemblies are available. Weld in replacements. Cost: $300--800 per side.

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Bottom End Bearing Wear

Critical
Engine
What happens

Low oil pressure at idle when warm (below 15 psi). A deep rumbling or knocking sound from the lower engine, particularly at idle and on acceleration. This is the main and big-end bearings wearing out.

Why it happens

Age and mileage. The B-series engine is tough but the white-metal bearings wear over 100,000+ km. Infrequent oil changes, overheating episodes, and oil starvation accelerate wear. The 3-main-bearing engines (1962--1964) are more susceptible.

How to fix it

Engine rebuild. The crankshaft is reground to the next undersize, new bearings are fitted, and the engine is reassembled with new gaskets and seals. Cost: $3,000--6,000 for a full rebuild.

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// FAQ

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