The Triumph TR6 was produced from 1969 through 1976 with about 94,619 examples produced with most destined for the United States. This became the Triumph's best-selling vehicle in history. Production continued into the middle of 1976, even after Triumph had introduced the TR6's replacement, the TR7.
The TR250 and its European counterpart, the TR5 PI, had been the interim models while Triumph worked hard on designing, building, and introducing its next open proper sports car. Sections of the TR6's body was similar to the prior series, with most of the visual changes appearing at the front and rear of the vehicle. It had a flatter hood, wider blackout grille, and front overhangs. The headlamps were moved out of the fenders. In the back, there was a Kamm-type tail.
Whereas the optional hardtop had been offered in two sections in the past, it was now a one-piece unit.
Powering the TR6 was a 2498 cc straight-six cylinder engine that produced just over 105 horsepower. In similar fashion to the TR250 and TR5 PI, the TR6 was carburetor for the American market and fuel injected for the European customers. Unfortunately for the US, the carburetor version offered less horsepower than its European sibling. The steering was by a rack-and-pinion unit. The gearbox was a four-speed manual with optional overdrive.
The interior was rather luxurious with its bucket seats and wooden dashboard. It was a true and refined sports car that continued on the proud and prosperous tradition of the TR series.
In mid-1971, the TR6 received slightly different gear ratios. In 1973, it was given a front spoiler and black bumper guards were added in 1974 to comply with US safety standards.By Daniel Vaughan | Jul 2011
The Triumph TR4 was introduced in 1961. The body had been given a modern and updated appearance by Michelotti but its drive-train and chassis were based on its TR predecessors. Production lasted until 1965 when it was replaced by the TR4A.
Prior to its release and while under development, the car was referred to by its codename, 'Zest'. The TR Series was a popular sports car but it did have its drawbacks and inconveniences. The introduction of the TR4 eliminated a few of the inconveniences by offering roll-up windows in place of the noisy and impractical side-curtains. A redesigned angular rear allowed for a trunk. The trunk and roll-up windows meant that items could be stored safely in the car. The prior plastic side curtains were easily torn and property was often stolen. The soft top could still be compromised but with the addition of the optional removable hard top, the TR4 became very versatile. The hard top had a fixed glass rear window and an integral roll-bar. The first five hundred produced had an aluminum center panel while the rest had a steel center unit.
The TR4 improved performance for the little sports car. The track was enlarged and the steering now used a rack-and-pinion unit. The transmission was now fully synchronized on all gears and the engine was enlarged slightly. An optional Laycock de Normanville electrically operated overdrive could be selected for second, third, and fourth gear.
The wheels original used were 15x4.5 inch disks. One of the more typical tires was the 165x15 bias ply. 48 lace wire wheels could be ordered and were often painted the same color as the car. Other popular options were to have them painted silver, matte, or polished chrome.
The TR4 was successful both in sales and in sporting events. They could often be seen competing in SCCA, hill-climb, and rally events where they provided plenty of podium finishes for their owners. The wet-sleeve engine was very convenient. The cylinder liners and pistons were easily changed allowing the vehicle to compete under different capacity rules. Some TR4 racers were given a supercharger which raised the 105 bhp SAE output to over 200.
In 1965 the TR4 was given an independent rear suspension, slightly modified frame, and various styling changes. In response to these changes the TR4 was dubbed the TR4A. Production of the TR4A continued until 1968 when it was replaced by the six-cylinder TR250.
The new suspension was an effort by the company to enhance the comfort of the vehicle and address customer complaints. Though the main difference between the TR4 and TR4A was the independent suspension, only about 75 percent of the TR4A models actually had this new suspension. These vehicles can be identified by the 'IRS' badge on the rear of the vehicle. The estimated 25% that did not receive the 'IRS' equipment had the solid rear axle configuration. The reasons for keeping with the solid rear axle was to provide a production racer for those who favored performance over comfort. The solid rear axle was easier to prepare for racing than was the 'IRS' setup. However, the independent rear suspension did not mean that the TR4A was not a competitive racer. The setup proved its potential at the Sebring 12 Hour race in 1966 when three TR4A models with 'IRS' finished in the top three spots.
The TR4 and TR4A were proven vehicles, with an attractive sticker price, sporty intentions, favorable appearance, and many conveniences of the day.By Daniel Vaughan | Sep 2006
An extremely successful sports car, the Triumph TR4 was produced in the U.K. by the Standard Triumph Motor Company from 1961. With a top speed of 110 mph, and costing around £1095, the TR4 became one of Triumph's best-loved cars thanks to its low cost of entry and capable open-top sports capabilities. The TR4 was stylistically quite a departure from its predecessor the TR3 and seemed to be just the car to bring the company into a brand new era.
Based on the chassis and drivetrain of TR predecessors, the TR4 was codenamed 'Zest' during development. Sporting a modern Giovanni Michelotti styled body, the new design was a big change from the classical cutaway door design of the earlier models, and allowed for full-sized doors with roll-up windows rather than side-curtains. The shapely tail end allowed for a spacious trunk, something that wasn't the norm for a sports car. A total of 40,253 TR4's were built during its production span.
This would be the first time that an adjustable fascia ventilation was utilized in a production vehicle. Other advanced features included a 'backlight' option; a specialized hard top that consisted of a fixed glass rear window with an integral rollbar and a detachable, steel center panel. This would be the first time there ever was such a roof system on a production vehicle. The Porsche 911/912 Targa would be introduced in the next 5 years, and this type of roof would eventually become a well-known option.
Replaceable, the rigid roof came with an easily folded and stowed vinyl insert and supporting frame called a Surrey Top. There has been confusion in the past with the entire hard top assembly mistakenly referred to as a Surrey Top. The rigid top and backlight assembly is listed as the Hard Top kit in original factory parts catalogues and the vinyl insert and frame are offered separately as a Surrey Top. In an attempt to stay ahead of the competition Triumph introduced modern features like wind-down windows to appeal to the important US market. Some dealers were concerned that buyers wouldn't fully appreciate these modern amenities, so a short run of TR3As or TR3Bs were produced in 1961 and 1962.
Triumph used the pushrod 4-cylinder engine that was based on the early design of the Ferguson tractor engine, but increased the displacement from 1991 cc to 2138 cc by increasing the bore size. Other updates and modifications to the manifolds and cylinder head allowed for some improvements, which resulted in the TR4A model.
For the vehicles earmarked to compete in the under-two-liter classes of the time the 1991 cc engine became a no-cost option. Select cars were fitted with vane-type superchargers since the three main bearing engine was susceptible to crankshaft failure if revved beyond 6,500 rpm. Superchargers allowed a TR4 to pump much more horsepower and torque at modest revolutions. Supercharged and otherwise performance-tuned, a 2.2-liter I4 version could produce more than 200 bhp, while a standard engine produced 105 bhp SAE. Like its predecessors, the TR4 was fitted with a wet-sleeve engine so the engine's cubic capacity could be changed by swapping the cylinder liners and pistons, for allowing a competitor to race under different capacity rules for competition use.
Other modifications from previous models included a wider track front and rear, a slightly larger standard engine displacement, rack and pinion steering and full synchromesh on all forward gears. The optional Laycock de Normanville electronically operated overdrive Laycock Overdrive could be picked for 2nd and 3rd gear, in addition to 4th, which effectively gave the TR4 a seven-speed manual close ratio gearbox. Initially the TR4 sported 15x4.5' disc wheels though optional 48-lace wire wheels could be ordered painted the same shade as the vehicles bodywork, in a matte or polished chrome finishes, or stove-enameled (matte silver with chrome spinners). The 155x15 bias ply was the most typical tire for the TR4. American Racing alloy; magnesium and aluminum wheels were offered in the U.S. at one time in 15x5.5' ox 15x6' sizes. The correct size radial-ply tire for the factory rims was 155x15, and only available from Michelin for an extravagant amount, was a problem when original owned opted for 60-spoke wire wheels. The standard 185x15 radials were much too wide to be fitted safely and as such, many owners had new and wider rims fitted and their wheels re-laced.
Thanks to Californian engineer Kas Kastner and his main driver Bob Tullius, the Triumph TR4 had quite a few racing successes in the U.S. under its belt. The TR4 won the E Production national championship in 1962. After this the SCCA reclassified the car to D Production, and the class title was won by Tullius in 1963 and 1964. Kastner and Mike Cook (who was in the advertising department at Triumph in NYC) convinced the Triumph Company to produce three new TR4s to race in the 12 Hours of Sebring race in 1963. Starting in the fall of 1962 the vehicles were prepared in California before flown to Florida for the endurance race in March of 1963. Kastner was Service Supervisor for the company in California at the time. Behind the wheel were Mike Rothschild and Peter Bolton from England, Bob Tullius, Charlie Gates, Ed Deihl, Bob Cole, Bruce Kellner and Jim Spencer. The vehicles finished overall 22nd, 24th, and 35th of 65 entrees, and in the 2.5 GT class the TR4 scored 1st, 2nd, and 4th.
This would be the start of the Triumph Competition Department that Kastner would head for numerous years and used to market the TR4. A privateer TR4 finished last in the '64 Sebring 12-hour race the following year. In 1966 Kastner returned to Sebring with four carefully prepared TR4As, three of which would finish winning the class. That same year Bob Tullius threw a piston in the most highly tuned vehicle, and didn't finish. The 1965 SCCA D Modified Championship was won at Daytona, driven by Charlie Gates against Ferraris and other prepared racecars.
During the mid-sixties the TR4 proved to be a celebrated rally car in the UK and Europe. As late as 1991 the TR4 continued to win an SCCA class championship and be raced in vintage sports car events. It was a common occurrence to see the TR4 in Australia hill-climb events, circuit racing events and various club rallies. 3 TR4s factory sponsored Team Triumphs were entered in the Canadian Shell 4000 rally. These models were apparently constructed with gussets on the chassis members and aluminum body panels to keep the car light as well as strengthen it. These engines were prepared by Kastner in NY after import and also fitted with lightweight magnesium wheels. Unfortunately they didn't place well in the rally, but the surviving models have proved to be quite valuable today. Neil Revington, proprietor of Revington TR in the UK owns one of these cars. Various replicas continue to be campaigned by privateers in vintage rally events throughout Europe.
The TR4A with IRS or independent rear suspension was the successor the TR4 in 1965. There wasn't much difference between the two models except for the rear suspension, which used trailing arms and a differential bolted to the redesigned chassis frame and a few minor updates. It is estimated that around 25% of TR4As not equipped with IRS were instead reverted to a live axle design like the TR4, which was adapted to fit the new chassis.
With only forty-three models ever produced, the most rare production TR4 model is the Dové GTR4. Rebuilt as a coupé by specialist coachbuilder for the Dove dealership in Wimbledon, London, and most conversions were based on the TR4 model, though the sales brochure pictures a TR4A version of these cars. Harrington Motor Bodyworks, who were well known for their construction of the Harrington Alpine, which was a similarly converted Sunbeam Alpine, did the convertibles.
Powering the Dové GTR4 were engine with period extras like a heater in the water jackets, which assisted in early morning starts. Optionally offered in the sales catalogue was some conversions fitted with fully balanced motors by Jack Brabham Motors of Laystall Engineering in London. Using the same materials found in the originally equipped standard TR4 were two jump seats behind the drivers seat. Some models featured a wood-rimmed wheel with riveted perimeter and auxiliary lamps under the front bumper bars. The glovebox lid featured a metalized identifying sticker with 'Dové' proudly displayed. Another 'Dové' logo was found on the rear deck to the left below the lid. To fit the new roof like, the side window glasses were specially shaped with a flat top edge. Custom fitted options included tinted swing-down see-through acrylic sun visors. Each model was customized individually and no two models were the same.
The Dové GTR4 was an attempt to fill the GT category for Europe, which is why the French nomenclature sported an inflection at the end of the word Dové. The Dové had pretty decent acceleration from 80 mph to 100 mph when compared to the standard model. The Dové carried a hefty price tag of £1250, nearly as much as a Jaguar E-Type. Today nearly a dozen Dové GTR4 are thought to still be in existence today.Sources:
By Jessica Donaldson
The Triumph TR6 was basically an updated version of the TR5, which itself was basically a TR4A with a beefy pushrod six-cylinder engine in place of a four. The TR5 had a new fuel-injection (PI for Petrol Injection) system which did not fully comply with U.S. emission standards. So in place of the TR5 PI version with its 150 horsepower, the US received a twin-carburetor TR250 model which produced 104 horsepower.
The 2.5-liter twin-carb engine would be used for the TR6 and mated to a four-speed gearbox. The exterior received mild updates courtesy of Karmann of Germany. The rear featured a chopped-off Kamm tail that had adequate space for luggage. The front was longer and the grille was wider. The removable, optional hardtop was updated with a more angular design.
The TR6 remained in production for seven years with few changes along the way. Perhaps the biggest improvement was in 1973, an updated camshaft. This gave the vehicle better low-speed tractability and improved its idle. That same year, an optional Laycock electric overdrive also became available.
During the early 1970s, the US became more safety conscious and strict rules were made for vehicles. To comply, the TR7 gained large, black bumper guards for 1973.
Production of the TR6 continued through mid-1976 when the newly introduced TR7 took over the legendary TR name. It would, however, not generate the enthusiasm or sales as its TR6 sibling.By Daniel Vaughan | Jul 2008