Triumph TR4A

Triumph TR4A
Overview
Manufacturer	Triumph Motor Company
Production	1965–1967
Body and chassis
Class	Sports car
Body style	2-door roadster
Layout	Front engine, rear wheel drive
Powertrain
Engine	2,138 cc (2.1 L) I4
Transmission	4-speed manual[1]
Dimensions
Wheelbase	2,235 mm (88.0 in)[1]
Length	3,962 mm (156.0 in)[1]
Width	1,473 mm (58.0 in)[1]
Height	1,270 mm (50.0 in)
Curb weight	1,016 kg (2,240 lb)[1]
Chronology
Predecessor	Triumph TR4
Successor	Triumph TR5/TR250

The Triumph TR4A is a sports car that was built by the Triumph Motor Company at its Coventry factory in the United Kingdom between 1965 and 1967.^[2]

The TR4A was an evolution of the TR4. While visual differences between the two were subtle, there were significant changes under the skin.

When the TR4 was introduced the styling by Giovanni Michelotti and the car's many amenities were favorably received, but the car's perceived harsh ride was not. To address this issue Triumph replaced the TR4's Hotchkiss drive system with an independent rear suspension. The change was indicated by an "IRS" badge attached to the rear of the new car.

Mechanical and Trim Changes

TR4A Engine

TR4A Interior

The new rear suspension was a semi-trailing arm system with coil springs and lever-arm shocks. This system more closely resembled that of the Triumph 2000 than the swing axle systems used in the Herald or Spitfire. The chassis was redesigned to accommodate the new suspension at the rear, with extensive changes to the side members and cross-bracing. The redesign had the desired effect, with reviewers commenting on the improved ride comfort, although some felt that the car's handling had not improved.^[3]

The chassis revisions resulted in a car roughly 22 mm (0.87 in) wider than the TR4, although length and height were unaffected. The wheelbase was 3 mm (0.12 in) shorter. The front track was unchanged, while the rear track grew by 13 mm (0.51 in) with the IRS. The car was heavier by 50 kg (110 lb).

Although consideration was given to both an enlarged 2.5 liter four-cylinder or a six-cylinder engine, the TR4A used the same long-stroke, high-torque Standard four-cylinder wet-sleeve engine seen in the TR4. While the bore, stroke, and displacement remained the same, changes to the cylinder head and manifolds raised net power to 104 bhp (78 kW) and torque to 132 lb·ft (179 N·m), an increase of 10 percent.

Apart from the increase in width and the IRS badge on the rear of the car, other changes included a revised grille and new hood badge. There was also a new line of chrome trim on the side, starting near the rear edge of the door and ending at the front of the car with integrated signal/marker lights, which were moved from their earlier position in the corners of the grille. New smaller front bumpers and a convertible top patterned after the one from the Herald completed the exterior differences. On the interior the fly-off handbrake lever was moved to the transmission tunnel between two revised seats, the gearshift lever was shortened and the white painted steel dashboard was now always covered by walnut, which had been optional in the TR4.

In 1965 the TR4A IRS sold in the UK for approximately £968. Wire wheels added £36, overdrive £51, heater £13 and seat belts £4 each;.^[4]

Coachwork

The TR4A continued to offer the "Surrey Top" hard top system as an option. This weather protection system comprises a rigid rear back light, a removable rigid roof panel and a soft fabric panel that was the actual surrey-top. The back light is attached to the rear of the passenger area semi-permanently. Either the roof panel or the soft surrey top bridge the gap between the top of the windshield surround and the top of the back light. This aesthetically foreshadowed the silhouette of Targa top cars.

Non-IRS

In response to requests from United States distributors Bud Forman and Les Genser^[5] Triumph developed a version of the TR4A fitted with a TR4-style rear live axle and made IRS an extra-cost option for that market.^[6] To locate the newly re-introduced leaf springs, spring brackets were added to the revised chassis. Live axle cars received a commissioning number (Triumph did not use serial numbers) that started with "CT". This was the same prefix used for TR4s. IRS equipped cars' commissioning numbers began with "CTC". The price in the United States was just under $2500.

Motorsports

Even though the SCCA declined to homologate the TR4A in 1965, Kas Kastner, Triumph's US Competition Manager, and his modified "Super Stock" TR4A were able to win a D-modified National Championship in 1965 at Daytona with driver Charlie Gates.^[7]

Bob Tulius' Group 44 and others successfully campaigned these cars during the 1965 to 1973 seasons, accumulating a respectable collection of finishes.^[8]

The apex of the TR4A's racing history is the team win by three TR4A IRS models at the Sebring 12-hour race of 1966, finishing 1st, 2nd and 3rd in their class.^[9]

Successor

In 1968 the four-cylinder TR4A was replaced by a new six-cylinder Triumph roadster. In the UK and most other markets the new model was named the TR5 and was equipped with Lucas fuel injection. In the United States the new car was called the TR250, and came with twin Zenith-Stromberg carburetters. The cars were otherwise identical.

Survivors

In Q1 2011 there were approximately 789 licensed and 153 SORN TR4As registered with the DVLA.^[10][11]

Specifications

• Engine: 2,138 cc (130.5 cu in), 4 cylinders inline, 86 mm bore, 92 mm stroke, 9:1 compression ratio, 104 bhp (78 kW).
• Turning circle: 10.1 m (33 ft)
• Capacities:

Fuel tank: 53.4 L (11.75 imp gal; 14.11 US gal)

Engine sump: 6.2 L (1.36 imp gal; 1.64 US gal)

Gearbox: 0.85 L (0.19 imp gal; 0.22 US gal)

• Acceleration in top:

30 to 50 mph (48 to 80 km/h): 8 s

40 to 60 mph (64 to 97 km/h): 8 s

60 to 80 mph (97 to 129 km/h): 11 s

References