1966 Triumph TR4A

The Triumph TR4 was introduced in 1961 (codenamed 'Zest') and based on the chassis and drivetrain of its much-loved TR3A predecessor, bringing with it a much more modern dashboard and all-new Michelotti-styled body. Power was from Triumph's proven long-stroke, high-torque Standard 2138cc overhead-valve four-cylinder wet-sleeve engine with dual SU carburetors and 104 horsepower and 132 lb-ft of torque. Passenger comfort was improved with wind-up windows and an optional hardtop. Mechanical updates included a wider track (by approximately 13mm) in the front and rear and the first use of adjustable fascia ventilation in a production car. It had a rack-and-pinion steering system, a full synchromesh four-speed manual transmission, and imitation wood dash trim.

The TR4A was the final iteration of the TR4, introduced in 1965 and bringing with it several subtle styling changes and upgraded specifications, including an independent rear suspension (IRS) replacing the previous Hotchkiss drive system. The new suspension required a chassis redesign with extensive changes to the side members and cross-bracing. The suspension provided exceptional rear-wheel camber control with excellent wheel travel, while softer springs improved the ride quality. Triumph was the first British car manufacturer to have all-independent suspensions under every car in their line-up. The validity of the IRS was proven in 1966 at the Sebring 12 Hours, where three IRS-equipped TR4As achieved a remarkable 1-2-3- class victory.

With six universal joints, three prop shafts, and two trailing arms, the IRS system was much more expensive than the previous live axle arrangement. United States distributors Bud Forman and Les Genser requested that a more affordable version of the TR4A be built with a TR4-style rear live axle, with the IRS being optional. The TR4As with the live axle used leaf springs, a revised chassis, and wore a commissioning number that began with 'CT.' IRS cars had commissioning numbers that began with 'CTC.'

The 1991cc engine was made available to buyers who wanted to participate in two-liter racing. When equipped with the optional overdrive, the TR4 was good for a top speed of almost 110mph.

Styling changes introduced on the TR4A were a new grille, decoration and badging, sidelights, and chrome trim along the door/wings. The hood was revised with proper catches at the front, ensuring it would stay on at speed (unlike the TR4).

The Triumph TR4 was produced from 1961 to 1965 with 40,253 examples built, and the TR4A was introduced in 1965 and built through 1967.

by Daniel Vaughan | Mar 2021