Development of a TR3 successor began as early as 1956, a period complicated by financial constraints and the departure of chief stylist Walter Belgrove. Triumph managing director Alick Dick invited Italian designer Giovanni Michelotti to create a concept car, resulting in the 1957 TR3 Speciale, nicknamed the “TR Dream Car”. Built by Vignale on a standard TR3 chassis, the TR3 Speciale incorporated American styling cues like tailfins and a full-width grille. Though deemed too expensive for production, Michelotti was commissioned to develop a revised TR, leading to the 1958 prototype, code-named Zest.
Around this time, Triumph’s Competitions department developed the high-performance “20X” engine, later named “Sabrina”. To accommodate this inline four-cylinder engine with dual overhead camshafts, a chassis was created with a widened track and extended wheelbase. Michelotti then designed the “Zoom” body for the 20X chassis, featuring a full-width body and headlamps positioned high in the grille. The Zoom body was used for three Triumph TRS race cars entered at the 1960 24 Hours of Le Mans, powered by 20X engines, achieving a formation finish but remaining unclassified. These cars were revised and returned to Le Mans in 1961, finishing ninth, eleventh, and fifteenth overall and winning the manufacturer’s team prize for Triumph. Ultimately, management opted for a design based on Zest, incorporating features from Zoom, resulting in the final TR4 design.
The TR4’s body, produced at Triumph’s Speke factory, eliminated the cutaway doors and sloping boot lid of previous TR models. Taller doors allowed for wind-down windows, and the rear body line enclosed a spacious boot. The bonnet featured an offset “bubble” to clear the engine’s two carburettors, with early cars having a shorter bubble than later models. An optional hard top, consisting of a fixed glass backlight with an integral rollbar and a detachable aluminium (early) or steel (later) centre panel, was available. This roof system predated the Porsche 911/912 Targa by five years. The interior was updated with adjustable fascia ventilation and a collapsible steering column.
The TR4 utilized the same ladder chassis with central cruciform bracing as the TR3, but with a 4-inch wider front track and a 2.5-inch wider rear track. It featured the Standard wet liner inline-four engine, increased in displacement from 1991 cc to 2138 cc. The engine had three main bearings and a cast iron head with two valves per cylinder. A 1991 cc engine was offered as a no-cost option for racing in under-two-litre classes. The car’s four-speed manual transmission was fully synchronised, an improvement over the TR3, and an optional Laycock de Normanville overdrive could be added for second, third, and fourth gears.
The TR4’s front suspension consisted of upper and lower wishbones and telescopic dampers, with revisions to the geometry over time. The rear suspension featured a live axle with semi-elliptical springs and lever-arm dampers. Rack and pinion steering replaced the earlier cam and lever system. Originally fitted with 15x4.5" disc wheels, optional 48-lace wire wheels were available in various finishes.
In motorsports, the TR4 achieved success in America through the efforts of Kas Kastner and Bob Tullius. In 1961, Waltman and Cone’s TR4 won its class at Sebring. In 1962, the TR4 won the E production national championship, leading to its reclassification to D production, which Tullius won in 1963 and 1964. In 1963, Kastner and Mike Cook convinced Triumph to enter three TR4s in the 12 Hours of Sebring, finishing 22nd, 24th, and 35th overall, and winning their class. A privateer TR4 finished last at the 1964 Sebring 12-hour race. Kastner also prepared cars for the Canadian Shell 4000 rally in 1964, featuring chassis gussets and aluminium body panels. The TR4 continued to be raced in vintage events, winning an SCCA class championship as late as 1991.
In 1965, the TR4A superseded the TR4, featuring a significantly revised chassis with independent rear suspension and a wider track. Approximately 25% of TR4As sold in the US retained a live axle system. A total of 43 Dové GTR4 and GTR4A fixed head coupés were produced by L. F. Dove Ltd., with coachbuilding by Harrington Motor Bodyworks. These conversions offered a weather-proof alternative to the drophead coupé, featuring a modified roofline and various custom options. One example was exported to Australia.
[unverified] The long-form study of the Dové GTR4 and its variations belongs to specialist marque clubs rather than this article's corpus.