The Triumph TR4 is a sports car produced by the Triumph Motor Company from 1961 to 1965. Successor to the TR3A, the TR4's chassis and drivetrain are closely related to those of its predecessor, but with an updated body designed by Michelotti.
Development Triumph began planning a successor to the TR3 as early as 1956. At the time, the company was facing a number of challenges. Lack of capital to fund development was partly relieved by the sale of Triumph's tractor division to Massey-Harris of Canada. A long overdue refresh of their small sedans was further complicated by the departure of chief stylist Walter Belgrove over a disagreement with the direction of the redesign.
After being introduced to Giovanni Michelotti, Triumph managing director Alick Dick invited the Italian designer to produce a concept car for the British company. Michelotti responded with the Triumph TR3 Speciale, also called the "TR Dream Car".
Built by Vignale on an unmodified TR3 chassis, Michelotti's TR Dream Car incorporated many styling cues from contemporary American practice, including tailfins, a full-width grille, lidded headlamps in the tops of the front wings, and a two-tone paint treatment. The TR3 Speciale debuted at the Geneva International Motor Show in March 1957. Triumph deemed the car too expensive to put into production, but did give the job of designing the new Triumph Herald to Michelotti.
Later in 1957 Standard-Triumph commissioned Michelotti to develop a serious proposal for a revised TR. A prototype, code-named Zest and built on a TR3A chassis, was complete by 1958. The Zest received a full-width body style, with headlamps that were inset from the sides and set high in the grille to stand above the bonnet, which was shaped into cowls over the lamps.
Around this time Triumph's Competitions department was working on a new high-performance engine with the development label 20X, later named Sabrina after contemporary British actress Norma Ann Sykes, the 20X is an inline four cylinder engine with dual overhead camshafts, and was expected to develop . To accommodate the engine, a chassis was created that widened the track by four inches and extended the wheelbase by six inches over those of the TR3.
In late 1958 Triumph commissioned Michelotti to create a body for the 20X development chassis. The new shape, named Zoom, was a full-width body, with tall doors having wind-down windows, and headlamps moved to the tops of the front wings. Two prototypes were complete by 1959; one convertible and one coupé with a removable roof panel.
The Zoom body was used for the three Triumph TRS race cars fielded at the 1960 24 Hours of Le Mans, which were powered by three 20X DOHC engines. The cars staged a formation finish, but were unclassified due to having failed to cover their mandatory distance. The cars were revised and entered again in the 1961 race, where they finished ninth, eleventh, and fifteenth overall, and claimed the manufacturer's team prize for Triumph.
By the middle of 1960, Triumph had two potential TR replacements — Zest and Zoom — with a combined program cost of £676,000. Originally, Zest had been conceived as the TR3's replacement, while Zoom was considered for production as an upmarket model. Having seen Zoom, some at Triumph wanted it to become the next TR, but the cost to produce a detuned 20X engine killed the project.
Ultimately management decided that neither Zest nor Zoom adequately addressed the target market, so the final design for the TR4 was based on Zest, but included some features from Zoom, including the wider track and hardtop option.
Features Body and chassis The TR4's new body, produced in Triumph's Speke factory, does away with the cutaway door design and sloping boot lid of the previous TRs. The taller doors allow room for wind-down windows in place of the previous side-curtains, making the TR4 a true convertible. The taller, more squared-off rear body line encloses a capacious boot for a sports car.
The car's bonnet has a power bulge or "bubble" offset to one side to clear the engine's two carburettors. Early cars have a short bubble, while cars after CT 6429 have a longer bubble.
The TR4 offered an optional hard top consisting of a fixed glass backlight with integral rollbar and a detachable centre panel made of aluminium on the first 500 units, and steel on subsequent cars. Featured on one of the Zoom prototypes, this was the first such roof system on a production car, predating the Porsche 911/912 Targa by five years.
On the TR4 the rigid roof panel could be replaced with a vinyl insert and supporting frame. While the rigid panel could not be stowed in the car, the vinyl insert and frame could be. The factory offered the rigid top and backlight assembly as the "Hard Top kit", and the vinyl insert and frame separately as the "Surrey top".
The revised interior introduced adjustable fascia ventilation and a collapsible steering column. Features such as these were seen as necessary to keep pace with the competition, particularly in the important US market where the majority of TR4s were sold.
The TR4 uses essentially the same ladder chassis with central cruciform bracing as the TR3. At , the TR4 has the same wheelbase as the earlier car, but its track widths are wider in front and wider in back than the earlier model.
Powertrain
The TR4 uses the same Standard wet liner inline-four engine that powered the TR2 and TR3 models, but with displacement increased from 1991 cc to 2138 cc by enlarging the bore from . The cast iron block carries the crankshaft in three main bearings, and the cast iron head has two valves per cylinder driven from a camshaft in the block via pushrods and rocker arms. The 1991 cc engine was a no-cost option for cars whose owners planned to race in the under-two-litre classes of the day. At different times the factory installed either a pair of SU H6 carburettors, or a pair of Zenith-Stromberg CD175s.
The car's four speed plus reverse manual transmission has synchromesh on all forward gears, an upgrade from the transmission in the TR3 which did not synchronize first gear. Additionally, the optional Laycock de Normanville electrically operated overdrive could be selected for second, third, and fourth gears, effectively providing the TR4 with a seven-speed close ratio gearbox.
Running gear The TR4's front suspension consists of upper and lower wishbones, and telescopic dampers. Running changes to the car included a revised front suspension geometry, indicated by a smooth upper wishbone, and a revised front brake caliper and pad size.
The rear suspension includes a live axle with semi-elliptical springs, and lever-arm dampers.
The TR4 is fitted with rack and pinion steering, replacing the cam and lever system used on the earlier TR models.
The TR4 was originally fitted with 15x4.5" disc wheels. Optional 48-lace wire wheels could be ordered with one of three finishes: painted the same colour as the car's bodywork (rare), stove-enamelled (matte silver with chrome spinners, most common) or in matte or polished chrome finishes (originally rare, but now more common). Originally, the tyres most commonly fitted were 590-15 bias ply or optional radial tyres. At one point, American Racing alloy (magnesium and aluminium) wheels were offered in the US as an option, in 15x5.5" or 15x6" size.
Production and sales
The first production TR4 was built on 18 July 1961, and received commission number CT1. The last car was built on 6 January 1965, with commission number CT40304. Final assembly of the cars was done at Triumph's Canley-Fletchamstead factory near Coventry. TR4s were also assembled from Complete Knock-Down (CKD) kits in Mechelen, Belgium and Borgo Panigale, Italy, the latter in a factory owned by Ducati.
American Triumph dealers were concerned that buyers might not accept the car's updated styling, so a brief special run of TR3s, commonly called TR3Bs, was produced for the US market in 1961 and '62. These cars have the body and chassis of the TR3A, but the 2138 cc engine and fully synchronised gearbox from the TR4.
A small number of TR4s were put to use as "Fast Pursuit Cars" by police departments in places such as Manchester City and the Southend-on-Sea Borough.
40,253 TR4s were built during its 3 and 1/2 year production run, of which 37,661 cars were sold in export markets (primarily the US), and only 2,592 cars sold domestically. In comparison, 8,635 TR2s were sold during its 3-year run from 1953–1955; 74,800 TR3s in an 8-year run from 1955 to 1962; 94,500 TR6s in a 9-year run from 1968–1976, and 111,500 TR7s over a 7-year run from 1975–1981.
As of Q2 2022 there were approximately 953 licensed and 216 SORN TR4s registered with the DVLA.
Technical data
Triumph TR4Detail:Engine: Standard wet liner inline-four engineBore × Stroke: Displacement: Maximum power: at 4,600 rpmMaximum torque: at 3,350 rpmCompression ratio: 9.0:1Valvetrain: Single cam-in-block, pushrods, rocker arms, 2 overhead valves per cylinderInduction: Two Stromberg 175CD carburettorsorTwo SU H6 carburettorsCooling: Water-cooledTransmission: 4-speed manual with reverse (optional overdrive)Final drive ratio: 3.7:1 (4.1:1 optional)Steering: Alford & Alder rack and pinionTurns lock-to-lock: 2.5Turning circle: Brakes f/r: Girling discs/drumsSuspension front: Upper and lower wishbones, coil springs, telescopic dampersSuspension rear: Live axle, semi-elliptical springs, lever-arm dampersBody/Chassis: Steel body on steel ladder chassisTrack f/r: (disc wheels) (wire wheels)Wheelbase: Tyres: 5.5/5.90x15 / 165x15 (Michelin X)LengthWidthHeight: Weight: Capacities: Fuel: Cooling: Sump: Transmission: (non-overdrive) (overdrive)Fuel consumption: Maximum speed:
Performance Acceleration Time 3.7 s 8.3 s 10.9 s 20.9 s 28.2 s 46.3 s
Motorsports The TR4 had a number of racing successes in America, primarily through the efforts of Californian engineer Kas Kastner and his top driver, Bob Tullius.
In 1961 the TR4 with commission number CT 7L, driven by George Waltman and Nick Cone, won first in class and thirtieth overall at Sebring. In 1962 the TR4 won the E production national championship, after which the SCCA reclassified the car to D production, which class Tullius won in 1963 and '64. Soon after the TR4 was introduced, Kastner and with Mike Cook from the advertising department at Triumph in New York City convinced the company to provide three new TR4s to race in the 12 Hours of Sebring in 1963. Preparation of the cars began in September 1962 in California, where Kastner was service supervisor for Triumph. The cars were then flown to Florida for the endurance race in March 1963. Driven by Mike Rothschild and Peter Bolton from England, Bob Tullius, Charlie Gates, Ed Deihl, Bob Cole, Bruce Kellner and Jim Spencer, the cars finished 22nd, 24th, and 35th overall of 65 entries, and first, second, and fourth in the 2.5 GT class. This was the genesis of the Triumph Competition Department led by Kastner for several years and used to publicize and market the TR4. The next year a privateer TR4 finished dead last in the 1964 running of the Sebring 12-hour race. Kastner returned to Sebring in 1966 with four carefully prepared TR4As, three of which finished winning the class. At Sebring in 1966, Tullius threw a piston in the most highly tuned car and did not finish. Perhaps the greatest racing victory for the TR4A was at Daytona, where a Kastner-prepared car driven by Charlie Gates won the 1965 SCCA D modified championship against Ferraris and other prepared race car exotica.