MGB GT

1965-1980 / Coupe / United Kingdom

All MGB GT problems All workshop issues

Critical Gearbox

Overdrive Failure

Symptoms

The overdrive fails to engage, engages intermittently, or drops out under load.

Cause

The Laycock overdrive is an electro-hydraulic unit. Common failures include a faulty solenoid ($80--150), worn wiring or switch ($20--50), low oil level in the gearbox (the overdrive shares gearbox oil), or worn internal components (clutch plates, pistons).

Fix

Start with the simple items: check the wiring, switch, and oil level.

If the solenoid clicks but the overdrive doesn't engage, the internal hydraulics need attention.

A full overdrive rebuild: $600--1,200.

Cost mentioned in fix

$600

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// More MGB GT problems

Other known issues

Common Gearbox

Second Gear Synchro Wear

A crunch or grind when shifting quickly from 3rd to 2nd gear, especially when the engine is cold.

Minor Body and Structure

Sill Corrosion (Inner and Outer)

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.

Critical Body and Structure

Floor Pan Corrosion

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.

Minor Body and Structure

A-Post Corrosion

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

Minor Body and Structure

Door Skin Corrosion

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

Minor Body and Structure

Rear Spring Hanger Corrosion

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

View all 18 MGB GT problems