Common Problems with the
1948 Morris Minor

On the Minor corrosion is not a cosmetic item — the box chassis rails, outer sills, spring hangers and chassis legs are structural and British roads rot them from the inside. Sills, floors, the central crossmember and rear chassis legs all corrode and the repair is labour-heavy because the suspension, steering and body all bolt to the affected metal. Cars now over forty years old are MOT-exempt, so nothing inspects them annually and hidden rot only surfaces at a show or on a ramp. A structural horror listed at £3,000 can cost far more than an honest car at £7,000.

The Minor's front suspension pivots on kingpins and trunnion bushes that must be greased regularly, and the lower trunnion wears first. The failure mode is not vague: if a worn lower trunnion gives way the front wheel can drop out suddenly and buckle under the car, stranding the driver. A sharp, pointed feel to the kingpin threads on inspection means the wear limit has been reached, and the correct repair is a complete new assembly rather than packing out the old one. New old stock trunnions are available loose from £25–£28 or as complete kits from £40, and NOS parts beat remanufactured kits on quality.

Every Minor sold from 1948 to 1952/53 carries the pre-war 918cc side-valve engine rather than the overhead-valve A-series that arrived with the BMC merger. The consequence is a parts problem rather than a reliability one: side-valve spares are trickier to source than A-series items, and Series MM components generally are getting harder to find as the surviving pool thins. For a buyer this changes the value equation — an MM is cheaper to buy than an A-series car but far more effort to keep on the road, and the wise course is to confirm availability with the specialists before committing to what is essentially a subassembly hunt.