16/05/2020
For enthusiasts of classic British sports cars, the Triumph TR series holds a special place. Spanning several decades, these roadsters delivered a blend of raw driving pleasure, distinctive styling, and a healthy dose of mechanical charm. Among the most discussed and often confused models are the TR5 and its successor, the TR6. While they share a common lineage and many underlying mechanical components, these two cars possess distinct personalities and design philosophies that set them apart. Understanding their differences is key to appreciating Triumph’s evolutionary journey in the late 1960s.
The Triumph TR5: A Potent, Fleeting Icon
The Triumph TR5, officially known as the TR250 in the North American market where it received carburettors instead of fuel injection, was a truly pivotal model, albeit one with a remarkably short production run. Introduced in August 1967 and phased out by September 1968, only 2,947 TR5 PI (Petrol Injection) models were built for the UK and European markets. This brevity in production has significantly contributed to its rarity and collectibility today. The TR5 was, in essence, an evolution of the Michelotti-designed TR4A, retaining its elegant, flowing lines and classic British sports car silhouette.
Under the bonnet, however, lay its most significant advancement: the 2.5-litre straight-six engine equipped with Lucas mechanical fuel injection. This sophisticated system, a rarity for a volume production car of its era, allowed the TR5 to produce a healthy 150 bhp, a substantial leap from the TR4A’s 104 bhp four-cylinder unit. This made the TR5 the first British production sports car to feature fuel injection, granting it impressive performance for its time, with a 0-60 mph sprint in just over 8 seconds and a top speed approaching 120 mph. The independent rear suspension (IRS), carried over from the TR4A, also contributed to a more refined ride and improved handling compared to earlier TR models.
Styling and Interior of the TR5
Visually, the TR5 maintained the classic Michelotti aesthetic. The front end featured the familiar round headlights and integrated indicators, while the rear remained relatively unchanged from the TR4A, characterised by its rounded, somewhat upright tail lights. The interior was also largely a continuation of its predecessor, offering a straightforward, driver-focused cockpit with a wooden dashboard and classic instrumentation. While not revolutionary in terms of comfort or luxury, it provided a functional and engaging environment for spirited driving.
The Triumph TR6: Refinement and Mass Appeal
Hot on the heels of the TR5, the Triumph TR6 burst onto the scene in September 1968, quickly becoming the best-selling model in the TR series. Its production run lasted until July 1976, with approximately 94,500 units produced worldwide, making it a far more common sight than its immediate predecessor. The TR6 represented a significant stylistic departure, the result of a redesign by German coachbuilder Karmann, rather than Triumph’s traditional collaborator Michelotti.
Karmann’s brief was to modernise the TR5’s appearance without undertaking a costly full redesign of the underlying body structure or chassis. The solution was a clever re-skinning, particularly at the front and rear. The TR6 adopted a more aggressive, squared-off look at both ends. The front featured a new grille, square headlights, and separate indicator lights, giving it a chunkier, more contemporary facade. The rear was completely restyled with a chopped-off, Kamm-tail design, horizontal rear lights, and a cleaner overall appearance. These changes were effective in giving the car a fresh, updated identity that resonated well with buyers in the late 1960s and early 1970s.
Engine and Chassis of the TR6
Mechanically, the TR6 largely retained the TR5’s excellent 2.5-litre straight-six engine. For the UK and European markets, the Lucas mechanical fuel injection system was carried over, delivering the same 150 bhp as the TR5. However, for the crucial North American market, stricter emission regulations led to the adoption of carburettors (initially twin Zenith-Strombergs, later single Stromberg or twin SU) and a reduced compression ratio, which significantly lowered power output to around 104-106 bhp. This distinction is crucial for understanding the performance differences between market-specific TR6 models.
The chassis and independent rear suspension were essentially identical to the TR5, meaning the TR6 inherited its solid handling characteristics. The interior, however, saw notable improvements. The TR6 featured a completely redesigned dashboard with a more modern layout, improved ventilation, and more comfortable seating, contributing to a slightly more refined and ergonomic driving experience.
Key Differences Laid Bare: TR5 vs TR6
While sharing a common core, the TR5 and TR6 diverge significantly in several key areas. Understanding these distinctions is crucial for enthusiasts and potential owners.
- Styling Philosophy: The most obvious difference lies in their aesthetics. The TR5 is the graceful swansong of Michelotti’s original TR design, retaining the classic rounded lines. The TR6, on the other hand, is Karmann’s bold reinterpretation, embracing a more angular, muscular, and contemporary look. The front and rear treatments are entirely distinct, making them instantly recognisable.
- Production Volume and Rarity: The TR5’s extremely limited production run makes it a significantly rarer car than the TR6. This rarity often translates into higher market values and a more exclusive ownership experience. The TR6, by virtue of its longer production and higher numbers, is more accessible and a more common sight at classic car events.
- Engine Specifics (Market Dependent): While both UK/European versions share the 2.5-litre PI engine, the TR6 had a much broader market reach, particularly in North America, where it was primarily sold with carburettors and lower power outputs due to emissions regulations. The TR5 PI, by contrast, offered consistent high performance across its limited markets.
- Interior Design: The TR5’s interior is a direct carry-over from the TR4A, offering a more traditional, simpler layout. The TR6 features a completely redesigned dashboard, which many consider more modern and user-friendly, with improved ergonomics and materials.
- Perceived Driving Experience: While mechanically similar, some purists argue the TR5 offers a slightly more raw and unadulterated driving experience due to its simpler interior and potentially lighter feel. The TR6, with its updated interior and styling, feels a touch more refined, yet still delivers that quintessential TR spirit.
Despite their differences, it’s important to remember the substantial common ground between the TR5 and TR6. Both cars share the robust separate chassis construction, the potent 2.5-litre straight-six engine block, and the four-speed manual gearbox (with optional overdrive). This shared mechanical DNA means that many parts are interchangeable, and the fundamental driving characteristics – the eager acceleration, the distinctive exhaust note, and the engaging open-top motoring experience – are present in both.
Owners of either model will appreciate the direct steering, the firm but communicative ride (especially with IRS), and the surprisingly practical boot space for a two-seater roadster. Both demand a degree of driver involvement that modern cars rarely offer, making every journey an engaging event rather than a passive commute.
Maintenance and Ownership Considerations
Owning a classic Triumph TR5 or TR6 is a rewarding experience, but it comes with its own set of considerations. Both models share common classic car ailments and require diligent maintenance.
- Rust: As with most cars of their era, rust is a primary concern. Critical areas to inspect include the chassis outriggers, sills, boot floor, and body mounts. Regular cleaning and rust prevention are paramount.
- Fuel Injection System: The Lucas mechanical fuel injection system, while powerful, can be complex and requires specialist knowledge for proper tuning and maintenance. Issues can include erratic idling, poor starting, and incorrect fuel delivery. However, when well-maintained, it performs admirably. Many North American TR6s, being carburetted, offer a simpler, though less powerful, system.
- Electrics: British Leyland era electrics are notorious. Frayed wiring, failing relays, and temperamental gauges are not uncommon. A thorough inspection and renewal of wiring looms can prevent many headaches.
- Parts Availability: Generally, parts for both TR5 and TR6 are good, thanks to a thriving aftermarket and dedicated specialist suppliers. However, specific body panels or interior trim unique to the TR5 can be harder to source due to its rarity.
- Specialist Support: Both models benefit from a strong network of clubs and independent specialists who possess the expertise to maintain and restore these vehicles.
For those considering ownership, a pre-purchase inspection by a reputable classic car specialist is highly recommended, regardless of which model you prefer.
Comparative Overview
| Feature | Triumph TR5 (UK/Europe) | Triumph TR6 (UK/Europe) |
|---|---|---|
| Design House | Giovanni Michelotti | Karmann |
| Production Years | August 1967 - September 1968 | September 1968 - July 1976 |
| Total Units (Approx.) | 2,947 (PI models) | 94,500 (all variants) |
| Engine Type | 2.5L I6 Lucas PI | 2.5L I6 Lucas PI |
| Peak Power (Approx.) | 150 bhp | 150 bhp (UK/EU PI), 104 bhp (US Carb) |
| Front Styling | Rounded, integrated indicators | Squared-off, separate indicators |
| Rear Styling | Rounded, vertical lights (TR4A-like) | Squared-off, horizontal lights (Kamm-tail) |
| Dashboard Design | Traditional, wood, TR4A-derived | Redesigned, more modern, full width |
| Rarity | High | Moderate |
| Market Value | Generally higher due to rarity | More accessible, good value |
| Driving Feel | Slightly more 'raw' | Slightly more refined, but still engaging |
Frequently Asked Questions (FAQs)
Q: Which Triumph TR model is faster, the TR5 or the TR6?
A: For UK and European models, both the TR5 PI and TR6 PI shared the same 150 bhp fuel-injected engine, offering very similar performance figures. American-market TR6 models, however, were carburetted and produced significantly less power, making them slower than their PI counterparts and the TR5 PI.
Q: Is the TR5 or TR6 more reliable?
A: Both cars share the same fundamental mechanicals and are subject to similar age-related reliability issues (e.g., rust, electrical gremlins). The Lucas fuel injection system on the PI models requires specialist knowledge for proper maintenance, but it can be reliable when well-tuned. Neither car is a 'set-it-and-forget-it' modern vehicle; they require dedicated maintenance and understanding.
Q: Which model is more expensive to purchase today?
A: The TR5, due to its extremely limited production numbers and unique position as the first fuel-injected British sports car, generally commands significantly higher prices than the TR6. The TR6, being more numerous, offers a wider range of prices depending on condition and specification.
Q: Are TR5 and TR6 parts interchangeable?
A: Many mechanical components, such as the engine block, gearbox, chassis, and suspension parts, are largely interchangeable between the TR5 and TR6. However, body panels (front and rear wings, bonnet, boot lid), interior trim, dashboards, and specific fuel injection components can differ and are not interchangeable.
Q: Are these cars suitable for daily driving?
A: While robust, neither the TR5 nor the TR6 is ideal for daily commuting in modern traffic without significant modifications. They lack modern safety features, air conditioning, and often have heavy steering at low speeds. They are best enjoyed as weekend cars, for touring, or as show vehicles, where their character can truly shine.
Conclusion
The Triumph TR5 and TR6 stand as fascinating examples of automotive evolution. The TR5, a rare and powerful bridge between the TR4A and its successor, represents a brief but glorious moment of engineering innovation with its ground-breaking fuel injection system. It's a car for the purist who appreciates rarity and the subtlety of Michelotti's final TR design.
The TR6, on the other hand, is the more widely recognised and popular icon. Karmann’s redesign gave it a modern edge that appealed to a broader market, and its longer production run cemented its place in classic car history. While sharing the mechanical heart of the TR5, the TR6 offers a slightly more refined interior and a distinct visual personality.
Ultimately, the choice between a TR5 and a TR6 often comes down to personal preference for styling, budget, and the desire for rarity versus accessibility. Both are quintessentially British roadsters, offering an engaging and spirited driving experience that continues to captivate enthusiasts around the world, embodying the very spirit of open-top motoring.
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