Triumph Stag (1970 to 1977)

Why people buy one

• A comfortable, refined four-seat open tourer with a smooth V8 and plenty of character.
• Most early engine problems are now understood; the Stag Owners Club says a well-sorted car is likely to be reliable.
• Choice of overdrive manual (overdrive standard from the 1973 model year) or Borg Warner automatic.
• Most cars came with both soft top and hardtop, giving genuine year-round use.
• Parts support and specialist knowledge are strong, and the club is large and long established.

What to weigh up

• The 3.0 V8 is sensitive to neglect: poor water circulation, a weak water pump and alloy heads that corrode without inhibitor led to overheating, warped heads and blown head gaskets.
• Rust is the main enemy, and Classic & Sports Car says it is worse on cars built from 1973.
• Many cars have been fitted with Rover V8, Triumph six or Ford V6 engines. Classic & Sports Car says conversions are falling from favour and a poor one can be dangerous, and most buyers prefer the original engine.
• Many cars have had quick cosmetic restorations, so an expert or club inspection is worthwhile.
• Hagerty UK describes the car as a tourer rather than a true sports car, with light, low-feedback steering and noticeable body flex.

Where they rust

• A-posts behind the carpet trim; Hagerty UK says if these are rotten, the rest probably is too.
• Inner and outer sills and jacking points.
• Front panel behind the headlamps, and the inner and outer front wings.
• Scuttle and floors; lift the rear seat base, as rot there can point to worse problems.
• Subframe and suspension mountings, including the rear trailing arm mountings.
• Rear suspension mounting and axle casing, where electrolytic corrosion can rot through.
• Door bottoms, wheelarches, bootlid edges, boot floor and valances.
• Hardtop edges.

Mechanical weak spots

• Cooling: the engine must have corrosion-inhibiting antifreeze and a healthy radiator; overheating at a standstill may only be a weak viscous fan coupling. Uprated radiators and electric fans are common and sensible.
• Timing chains should be renewed about every 30,000 miles; a rattle from the front of the engine means chains and tensioners need urgent attention.
• Head gaskets fail after overheating; look for coolant loss and emulsified oil.
• Manual gearbox: a noise that quietens when the clutch is pressed in neutral points to a worn layshaft bearing; synchromesh weakens and overdrive faults are often electrical. Automatics should shift smoothly with clean fluid.
• Rear axle and driveshafts: listen for whine and rumble, and check the sliding driveshaft splines have been greased, as seized splines upset the handling.
• Steering: power-assisted rack; over-light steering suggests a faulty spool valve, and worn rack mounting bushes reduce precision.
• Electrics: most faults come from aged wiring and poor connections; check all lights, instruments and the electric windows.

At a Mathewsons viewing

• Check the commission number against the V5C (UK cars carry an LD prefix, with Mk2s from LD20001), and check the details match the claimed Mk1 or Mk2: Mk1 cars have Rostyle trims on steel wheels and a three-window hood, early Mk2s have coachlines and a black tail panel.
• Open the bonnet and look for the original Triumph V8, signs of coolant leaks or overheating, coolant colour and sludge under the oil filler cap.
• Lift the carpets and rear seat base and look at the A-posts, floors and sills for rust or fresh filler, and use a torch underneath at the jacking points and suspension mountings.
• Check the hardtop's edges for rust and the hood and frame for splits or damage, and confirm the hood is in its well if the hardtop is fitted.
• Ask for receipts for timing chains, cooling work and any engine rebuild; if staff start the car, listen for front-end chain rattle and watch the temperature gauge, but do not assume it will be started.

Parts, specialists and clubs

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Sources

• Buyer's guide: Triumph Stag (Classic & Sports Car), 20 February 2020
• Buying guide: Triumph Stag (1970 to 1977) (Hagerty UK), 5 January 2021
• Triumph Stag buyer's guide (Classics World), 18 September 2024
• Used car buying guide: Triumph Stag (Autocar), February 2020
• Differences between Mk I and Mk II (Stag Owners Club), accessed 14 October 2026
• Buyer's guide (Stag Owners Club), accessed 14 October 2026