The Triumph TR4 was produced by the British Triumph Motor Company from 1961 to 1965. Code named “Zest” during development, the car was based on the chassis and drivetrain of the previous TR sports cars, but with a modern Michelotti styled body. 40,253 cars were built during production years. The new TR4 body style did away with the cutaway door design of the previous TRs to allow for wind-down (roll-up) windows in place of less convenient side-curtains. The angular rear allowed a boot (trunk) with considerable capacity for a sports car. Advanced features included the use of adjustable fascia ventilation, and the option of a unique hard top that consisted of a fixed glass rear window (called a backlight) with an integral rollbar and a detachable, steel centre panel (aluminium for the first 500 units). This was the first such roof system on a production car and preceded by five years the Porsche 911/912 Targa, which has since become a generic name for this style of top.
On the TR4 the rigid roof panel was replaceable with an easily folded and stowed vinyl insert and supporting frame called a “Surrey top”. Features such as wind-down windows were seen as a necessary step forward to meet competition and achieve good sales in the important US market, where the vast majority of TR4s were eventually sold.
The pushrod Standard inline-four engine, was designed for use by the Ferguson TE20 tractor. The TR4 engine was continued from the earlier TR2/3 models, but the displacement was increased from 1991cc to 2138 cc in the TR4 by increasing bore size. Gradual improvements in the manifolds and cylinder head allowed for some improvements culminating in the TR4A model. The standard engine produced 105 bhp (78 kW) SAE but, supercharged and otherwise performance-tuned, a 2.2-litre inline four version could produce in excess of 200 bhp (150 kW) at the flywheel. Other key improvements over the TR3 included a wider track front and rear, slightly larger standard engine displacement, full synchromesh on all forward gears, and rack and pinion steering. In addition, the optional Laycock de Normanville electrically operated overdrive could now be selected for second and third gears as well as fourth, effectively providing the TR4 with a seven-speed manual close ratio gearbox.
Acknowledgements to Wikipedia
Engine – 4 Cylinder 86mm x 92mm 2138cc, wet liners
Power – 100 bhp (75kW) at 4600 rpm