The Triumph TR7 was manufactured from September 1974 to October 1981 by the Specialist Division of British Leyland. It was initially produced at the Speke, Liverpool factory, moving to Canley, Coventry in 1978 and then finally to the Rover Solihull plant in 1980. The car was launched in the United States in January 1975, with its UK home market debut in May 1976. The UK launch was delayed at least twice because of high demand for the vehicle in the US, with final sales of new TR7s continuing into 1982.
The car, characterised by its "wedge" shape and by a swage line sweeping down from the rear wing to just behind the front wheel, was commonly advertised as: "the shape of things to come". The design was penned by Harris Mann.
The interior trim was revised in March 1977, with the broad cord seat covers being replaced with red or green "tartan" check inserts with black leather effect vinyl edging. The tartan trim is also reflected in the door cards in padded matching red or green tartan cloth inserts in the black leather effect vinyl.
The development of the convertible version of the TR7 required the interior light, which was in the headlining, to be removed. This was replaced by lights with integral switches in each of the door cards. A map light, mounted between the seats on the back panel below the rear parcel shelf, was deleted. The convertible also required a smaller fuel filler cap, as the deck area in front of the boot lid was reduced to allow for the stowage of the hood. These modifications were also applied to the hard top for the 1978-year model (starting after the factory's summer shutdown in 1977), presumably to maintain commonality of parts on the assembly line. The wheel trims were also changed at this time, from smaller black trims that covered only the centre of the wheels, to larger silver ones, covering the whole wheel. Only a small number of 1978 of year model cars, with the smaller filler cap and lights in the door cards, were produced at Speke, due to the industrial action there in 1977 - 78.
The development of a V8-engined version, which became the Triumph TR8, required an addition bulge in the bonnet, to clear the carburettors. This produced the "double bulge" or "double bump" bonnet, characteristic of TR7s and TR8s built at Canley and Solihull. However, at least some of the TR7s built at Canley have single bump bonnets; though it is possible these were cars that had not been completed at Speke, possibly due to the industrial action there, and finished off at Canley after production was moved.
During production at Canley, the seat trim was again revised, with a plaid cloth in navy blue or tan, with matching coloured leather effect edging, and matching door cards. A further trim change during production at Solihull saw the use of a ruched velour in blue or tan on the seats, with matching inserts on the doors. Also, the internal door lock buttons were changed from the earlier standard BL round ones, to rectangular buttons held on with small grub screws. There was also a change to the trip mile counter's reset button, which became a push type operated through the instrument "glass", rather than a turn type under the dash.
Because of proposed US legislation on roll-over protection at the time of its launch, the TR7 was not initially available as a convertible. In early 1979, Triumph belatedly introduced a convertible version, called the TR7 Drophead Coupé (DHC), which first went on sale in the US (the original hardtop model being known as the Fixed head Coupé, or FHC). A small number of pre-production cars were manufactured at Speke in 1978, soon after the pre-production TR7 V8 (later designated TR8) and TR7 Sprint cars. The British market received it in early 1980. The prototype for the convertible version of the original Harris Mann design came from Michelotti and the engineering to make it work was done by Triumph.
A variant of the TR7 powered by the Dolomite Sprint engine (dubbed the TR7 Sprint) was developed, but never put into full production; though British Leyland had the 16-valve engined TR7 homologated for use in competition. These cars can be identified by a different chassis number to the production 8-valve model: prefixed ACH rather than ACG, etc. The original engines are also numbered with the format CH****HE, rather than the VA****HE format of Dolomite 16-valve engines. Production records at the British Motor Industry Heritage Trust (BMIHT) cover 58 prototype and pre-production cars, all Fixed heads, built between February and October 1977. Another car, without production records, is identified by DVLA details, and the possible existence of two more has been inferred from the commissioning number sequence; making a possible maximum of 59 to 61 cars, of which several still exist in the UK and elsewhere. These cars were built at the BL plant at Speke, at the same time as the pre-production runs for the convertibles and TR7 V8s, including a run of about 30 cars built on the line during the factory changeover to the 1978 year model in June 1977. However, it is claimed that some cars at least were converted at Canley from completed TR7s built at Speke.
Production of the TR7 Sprint stopped with the closure of the Speke plant. However, the failure of the TR7 Sprint to go into full series production is also blamed on BL's Sales and Marketing Department because they claimed its performance was not sufficiently different from the TR7, though its top speed and 0–60 mph (97 km/h) time were almost identical to those for the US specification carburettor version of the 3.5 litre 134 bhp (101 kW; 137 PS) Rover V8 powered Triumph TR8. Also, the Sprint engine was unsuitable for the emission-control equipment necessary for sale in the US, which was Sales and Marketing's main target market for the TR7 and TR8.
Even so, BL required some, probably about 50, 16-valve engined TR7s suitable for normal sale before the end of 1977. This was for the re-homologation of the 16-valve head to allow the 16-valve TR7 rally car to be used in the 1978 season following a change to the FIA's rules. That the TR7 Sprint was used in this is shown by a series of six photographs in the British Motor Museum's archives, taken on the 1st of November and listed as TR7 Sprint Homologation. The 16-valve head was approved for use with the Group-4 rally car a second time in February 1978 in time for the Mintex Rally.
Converting a two-valve TR7 to the four-valve Sprint specification is relatively simple, compared to conversion to TR8 specification, because the TR7 and TR7 Sprint have virtually identical engine blocks. As a result, there are a number of such converted TR7 models around. "There is a [comparatively] large number of privately built Sprint conversions about ... Buyers should beware of this if they are asked a premium price for an alleged 'genuine' TR7 Sprint.
In 1980, a limited-edition version of the TR7 Drophead was launched for the US market by the US importer. Called the TR7 Spider, it was available only in Maraschino Black, with reflective red striping and badging plus black interior trim. Alloy wheels and the steering wheel from the TR8 were fitted, along with a "pewter grey" carpet and grey striped upholstery. Based on an exhaustive inventory of the factory build cards at the British Heritage Motor Centre archives, it has been confirmed that 1,070 carburetted Spiders were built at the Solihull factory with an additional 548 fuel-injected (Bosch L-Jetronic) Spiders built specifically for California. VIN numbers for Spiders run from 400301 to 401918 overall and for the fuel-injected version from 401374 to 401918. All the Spider-specific equipment was installed at the factory, with the exception of the radio/cassette, which was stored in the boot and installed at the port of entry.