Grandfather’s Ax: The Many Evolutions of the Triumph TR4, Part 2: TR5, TR250, and TR6

A NEW BOTTLE: THE TRIUMPH TR6

With the TR5 PI/TR250, Triumph had belatedly managed to give the TR a new body, a new chassis, and a new engine. However, by the time all that was accomplished, the “new” body was six years old and no longer looked particularly new, a point Bruce McWilliams had made in strong terms during the development of the six-cylinder cars. In mid-1967, even before the TR250 and TR5 went on sale, Standard-Triumph decided that a further update was needed post-haste.

1970 Triumph TR6 badge
The Triumph TR6 looked like an all-new car, but was essentially a clever and elaborate facelift of the TR5 PI/TR250. (author photo)

Back in 1964, Triumph had developed a prototype called Fury, a Michelotti-styled convertible with fully independent suspension (similar to the layout subsequently adopted for the TR4A), a six-cylinder engine, and monocoque construction. Although the Fury was smaller than the TR4, it otherwise seemed a logical next step for the TR. Body-on-frame sports cars were already becoming somewhat old-fashioned, particularly after the arrival of the unitized MGB. However, switching to monocoque construction would have meant an all-new body structure, which was not yet feasible.

With the acquisition of Rover, Leyland was doing quite well, but its resources were already heavily committed to other projects, including a rethinking of the front-wheel-drive 1300 family car line (which resulted in the cheaper rear-wheel-drive Toledo and Dolomite), a facelift of the big saloons, and development of the new Stag, a V8-powered sports car to be lobbed in the general direction of the E-type Jaguar and W113 “Pagoda” Mercedes. A completely new TR was not an immediate priority, particularly since the existing car had already received an updated chassis and a new engine.

The alternative was an extensive makeover, enough to give the familiar package a fresh look without the expense of an all-new body. Ordinarily, Standard-Triumph would have turned to Michelotti for such a job, particularly since they wanted it done quickly, but Leyland and Triumph had more pressing need for his talents elsewhere, including the restyling of the 2000 and 2.5 PI saloons. The TR facelift was done instead by Gerhard Giesecke of the West German coachbuilder Karmann, which didn’t flinch at Triumph’s daunting deadline and offered a highly competitive price for both the restyling and tooling. Giesecke’s design, reportedly developed with considerable input from Triumph’s North American organization, went from clay to production in a little over a year and Leyland was very pleased with the results, earning Karmann the tooling contract for the 2000/2.5 PI Mk 2.

Triumph TR6 hardtop side © 2012 Peter Laurence (used with permission)
An early (pre-1972) North American Triumph TR6 hardtop. The new one-piece hardtop was one of the few elements of the TR6 not designed by Karmann: It was the work of Les Mann’s in-house styling team in Coventry. The TR4’s two-piece hardtop was expensive to manufacture and despite its novelty Triumph had never figured out how to merchandize it effectively, to the later regret of some company executives. Note the small pip ahead of the door, which is the ubiquitous blue British Leyland fender badge. (Photo: “Triumph TR6” © 2012 Peter Laurence; used with permission)

The result of Karmann’s efforts was the Triumph TR6, which replaced the TR5 and TR250 on the production line in late 1968. Like the original TR4 of seven years earlier, the TR6 was less new than its extensively revamped styling implied. Much of the tooling was new, as were the fenders, bonnet, grille, and front and rear clips, but from a structural standpoint, the TR6 was largely carryover. The new fenders made the body slightly longer than before, but the lack of bumper overriders (at least initially) trimmed overall length slightly to 155 inches (3,937 mm). Wheelbase and overall width were unchanged, but the addition of wider 5.5×15 wheels increased tread width to 50.25 inches (1,276 mm) front and 49.75 inches (1,264 mm) rear.

There were no major chassis changes for the TR6, but a front anti-roll bar was added and the spring and damping rates retuned in an effort to better balance ride and handling. (The anti-roll bar was the first on a production TR, although anti-roll bars had been on the competition parts list for years.) Also unchanged were the engines: the carbureted six for North American cars, the 2.5 PI engine for other markets, where the TR6 was typically badged “TR6 PI.”

1973 Triumph TR6 engine
The North American Triumph TR6 retained the TR250’s carbureted six, initially with an unchanged net output of 104 hp (78 kW) and 143 lb-ft (194 N-m) of torque. Non-California cars retained dual Zenith-Stromberg carburetors until the end of the model run in 1976, but stricter California emissions standards limited cars bound for that market to a single carburetor, with predictable effects on power. Even the 49-state cars became increasingly festooned with emissions-control devices throughout the TR6’s run, including exhaust gas recirculation and the air injection pump Triumph had previously avoided. Net power rose from 104 to to 106 hp (78 to 79 kW) in 1972, but net torque output fell by about 7%, to 133 lb-ft (180 N-m). (author photo)

The TR6 wasn’t substantially heavier than the TR5/TR250, so performance was — again — little changed. Road & Track‘s 1969 TR6 test car was almost dead even with their previous TR250 up to 100 mph (161 km/h), reaching 60 mph (97 km/h) in just under 11 seconds; top speed for carbureted cars was again in the 107-110 mph (172-176 km/h) range. The TR6 PI, meanwhile, could complete the 0-60 mph (0-97 km/h) run in just over 8 seconds and reach 118-120 mph (190-193 km/h) with overdrive. Reviewers found the TR6’s ride and handling more composed than the TR250’s, although the anti-roll bar made for pronounced understeer where the early TR4 would hang out its tail at will.

At home, the starting price of the injected TR6 was up £35 (about $84) to £1,020 (£1,333 19s 2d with tax). Thanks to the recent devaluation of the sterling, the U.S. TR6 was actually a bit cheaper than the TR250 at launch, starting at $3,275 POE. However, U.K. prices would escalate rapidly over the next few years, driving U.S. prices ever higher.

1973 Triumph TR6 front 3q
Aside from stripes and decals, one of the few obvious visual changes to the Triumph TR6 during its eight-year run was the addition of an under-bumper spoiler for 1973. The spoiler, which was always black regardless of body color, reportedly reduced front-end lift at speed, although that was becoming increasingly academic in the U.S. by this time. (author photo)

THE BMC-LEYLAND MERGER

By the time the TR6 debuted in January 1969, the U.K.’s Wilson government had coaxed Leyland into a merger with the larger but considerably less solvent British Motor Holdings, which included BMC (Austin, Morris, Riley, Wolseley, and various suppliers) and Jaguar. The chairman of the new British Leyland Motor Corporation was Leyland/Standard-Triumph boss Donald Stokes, who received a life peerage for his trouble. Consolidation and rationalization were not yet on the table, although they would follow soon enough, but the merger did mean a management shuffle, including the departure of Triumph general manager George Turnbull and technical director Harry Webster for Austin-Morris, replaced by Turnbull deputy Cliff Swindle and Rover’s C. Spencer King, respectively. Less happily, British Leyland also inherited BMC’s financial problems and ongoing labor disputes.

1973 Triumph TR6 rear 3q
U.S.-spec Triumph TR6s became progressively more gaudy throughout in the early seventies, adding cosmetic touches like the Union Jack decals on the rear fenders for 1973. This car’s roll bar, alloy wheels, and luggage rack were not standard equipment, of course, although the latter items may have been dealer accessories. Note the angular Kamm-style tail panel, which in a typically seventies touch was always painted black, regardless of body color. (author photo)

Around the time Spen King arrived, Triumph began development of successors for the GT6 and TR6, codenamed Lynx and Bullet respectively. The original plan was for the Bullet to debut by the 1973 model year in order to spare Triumph the expense of modifying the TR6 to comply with the new U.S. bumper standards, but for various reasons (discussed in more detail in our article on the TR7) that proved impossible. As a result, the TR6 ended up lasting far longer than intended: almost eight years rather than four or five.

Because a replacement was already in the works — and because money was becoming increasingly scarce — the TR6 enjoyed little additional development during the remainder of its life. Most of the changes it did receive were for either regulatory compliance or production rationalization, such as the addition of a lockable steering column for 1970 and the installation in mid-1971 of the stronger four-speed gearbox from the Stag. The Stag’s automatic transmission was apparently not considered, although by this stage, American buyers might have been receptive.

Carbureted TR6s picked up a few horsepower, but sacrificed some torque and a fair measure of driveability in the ongoing struggle to remain emissions compliant. Stricter standards forced California cars to rely on a single Stromberg carburetor, making them particularly anemic; we don’t know if British Leyland even quoted output figures, which were also omitted from contemporary MG brochures for similar reasons. Progressive reductions in compression ratio also played hob with fuel economy.

Leyland never tried to federalize the injected engine, both for cost reasons and because it remained a source of service headaches in other markets. However, the U.S. organization did eventually persuade the SCCA to homologate the Lucas system, making the TR6 more competitive in C Production. Unfortunately, the Triumph was still hard-pressed by the Datsun 240Z.

1975 or 1976 Triumph TR6 front 3q © 2008 Geoffrey Gallaway CC BY-SA 2.0 Generic
A late (1975 or 1976) North American Triumph TR6. The roll bar again is not standard, but the bulbous overriders were, increasing overall length to 162.1 inches (4,117 mm) and curb weight to around 2,450 lb (1,111 kg). The shimmed suspension also required some changes to the indicator lights. (Photo: “Triumph TR6” © 2008 Geoffrey Gallaway; used under a Creative Commons Attribution-ShareAlike 2.0 Generic license)

U.S. safety regulations were almost as problematic for Triumph as emissions standards. New roof crush standards were passed in 1971 that would have effectively outlawed convertibles and roadsters, although a federal district court judge eventually overturned that rule before it went into effect. Another challenge was the federal 5 mph (8 km/h) crash standards that took effect in 1973. Although sports cars received a one-year exemption, in mid-1974 Leyland was forced to add bulky and awkward-looking overriders to the bumpers of North American TR6s (and MGBs) and shim their suspensions to bring bumper height to the regulation level.

While the TR6 PI was spared those indignities, the injected cars eventually lost some of their teeth as well. For the 1973 model year, widespread complaints about the 2.5 PI engine’s rough idle prompted Rover-Triumph (the two organizations had recently merged) to substitute the shorter-duration camshaft from the federalized cars, which provided better low-speed behavior at the expense of peak output. Net output fell to 124 hp (93 kW) and 143 lb-ft (194 N-m) DIN. At the same time, all TR6s adopted the newer Laycock de Normanville J-type overdrive, which had a taller overdrive ratio and could no longer be used on second gear, a feature once beloved of rally drivers. A minor consolation was that the overdrive became standard on all TR6s in 1974.

1975 Triumph TR6 dash
The dashboard of a 1975 Triumph TR6 convertible. In the main, the interior of the TR6 changed little over the years, although there was a bewildering assortment of different seats (which reclined from late 1969 onward) and overdrive became standard from 1974. This car’s leather-wrapped wheel appears to be an aftermarket accessory. (author photo)

TR IN TWILIGHT

Contemporary critics who bothered to test the late Triumph TR6 conceded that it still had its charms, including rugged good looks and an entertaining basso profundo exhaust note, but in other respects, the Triumph seemed increasingly anachronistic. Although the independent suspension was as modern as any, the TR6’s handling was nothing special by the standards of the mid-1970s and the body-on-frame structure allowed more quiver and shudder than newer unitized rivals. The controls were heavy and there were assorted minor annoyances that reflected the age of the basic package. The rival Datsun 240Z felt much more modern and was faster than even an injected TR6. For about the same money as a TR6 PI, British buyers could also have a Ford Capri 3000 GT, which had a less-sophisticated suspension but comparable performance and greater practicality.

Despite all that, despite the consolidation of British Leyland’s U.S. dealer networks, despite a dismal 16.4 mpg (14.3 L/100 km) showing on the first Environmental Protection Agency fuel economy cycle, despite ongoing complaints about quality and dealer service, and despite a price tag that by 1975 was closing rapidly on $5,000, TR6 sales remained consistently strong. Even the ugly bumpers didn’t stop the TR6 from selling around 14,000 units in 1974, its peak year — a major percentage of Leyland’s North American sales.

The TR6 was still regularly seen on the racetrack as well. For 1975, the factory-sponsored teams reverted to carbureted engines and were reclassified in D Production, where the TR6 was far more competitive. Cars prepared by Bob Tullius’ factory-backed Group 44 team took the SCCA D Production national championship in both 1975 and 1976. The latter victory was somewhat awkward for British Leyland’s U.S. organization because the winning TR6, an ex-Group 44 car driven by actor Paul Newman, actually vanquished a new TR7 driven by Lee Mueller of Huffaker Engineering, Leyland’s West Coast team!

1975 Triumph TR6 rear
This is a 1975 North American Triumph TR6, but the present owner has apparently discarded the bumper overriders and, if our eyes don’t deceive us, the shims that would ordinarily raise the ride height. (author photo)

Had British Leyland been so inclined — and had unfavorable late-seventies exchange rates permitted — the TR6 could probably have survived at least until the introduction of the convertible TR7 in 1979, but it was not to be. Rover-Triumph was eager to drop the older Triumph six at the earliest opportunity, particularly the expensive and problematic 2.5 PI version; the TR7 would use Triumph’s slant-four “Saab engine” (with the Rover V8 to follow after launch) while the successor to the 2000/2.5 PI saloons, the Rover SD1, was slated to use an all-new, Triumph-developed OHC six. Delays with the latter, as well as British Leyland’s near-bankruptcy, kept the carbureted six alive in the big Triumph saloons until 1977, but the injected engine ceased production in the summer of 1975, also putting an end to both the 2.5 PI saloon and the TR6 PI. We assume that TR6 PI sales, which had never topped about 3,000 a year, did not justify substituting the carbureted six, although Rover-Triumph did install a carbureted version of the 2,498 cc (152 cu. in.) engine in the saloons.

The North American TR6 survived another year, but finally expired in July 1976, bringing production to 94,619 units. U.S. dealers were sad to see it go; the TR6 was an easier sale than the controversial new TR7 and had healthier profit margins to boot. The last TR6 off the line went to Bob Tullius, marking the end of an era.

6 Comments

Add a Comment
  1. what engines will fit my 72 tr6? id like to
    put an early Toyota Corolla(DXL) or Nissan
    (Datsun)?????
    PLEASE HELP!

    1. Judy,

      I omitted your phone number — if you really want, I can put it back, but generally posting your phone number online is asking for trouble. If anyone wants to reach you, they can contact me via the contact form and I will forward their information to you.

  2. Thanks very much for your well-researched article. It brought back many happy memories of my all too brief years with my restored 1967 TR4A IRS. I’ve often fantasized about tracking down and importing a TR5, but your description of the overly fussy PI has driven the last nail in that coffin.

    1. A lot of mechanical injection systems are fairly fussy things, at least in street car applications. The big problem, from an ownership standpoint, is having someone who knows how to work on it when necessary. That can be a big headache with a system not ever sold in the U.S.

  3. Did I miss mention of the TR6 PI listed in the title link?

    1. It is described in the text (it’s not in the title, but the title was already getting long). However, the TR6 PI was in most mechanical respects a TR5 PI with the restyled body. There were some mechanical changes to rationalize production with the 2.5 PI and to back off on the cam timing for a smoother idle, at the cost of some power.

Leave a Reply

Your email address will not be published. Required fields are marked *

Click here to read our comment policy. You must be at least 18 to comment. PLEASE DON'T POST COPYRIGHTED CONTENT YOU AREN'T AUTHORIZED TO USE!
Except as otherwise noted, all text and images are copyright © Aaron Severson dba Ate Up With Motor. (Terms of Use – Reprint/Reuse Policy) Trademarks referenced herein are the property of their respective owners and are used here for informational/nominative purposes.