Recent Forum Topics

The Triumph 2000 Story - Gilding the Lily: The Mk2 Models, 1969-1974

The Triumph 2.5 PI Mark 2

The Triumph 2.5 PI Mark 2

Crucially, few if any testers had anything but praise for the fuel-injected engine, whereas real-life customers were beginning to report service difficulties.  One notorious malady concerned the high-pressure electric fuel pump which, despite its competition origins, tended to run hot at the best of times and was thus prone to vapour-locking and resultant stalling under high ambient temperature conditions or if the fuel supply was in any way impeded.  Although many reported problems related less to the PI set-up itself than to unfamiliarity or poor workshop practice on the part of mechanics, many of whom were employed by new centralised BL franchises with little or no previous Triumph experience, for customers the resulting difficulties could be very real and an unfortunate reputation for unreliability soon began to dog the 2.5PI1.

With production of the new Mk2 range running at an all-time high of around 2500 a month, the need – or, indeed, opportunity – for significant changes during the first few years’ production was relatively low.  One of the first was the standardisation of a front anti-roll bar on estate cars; ironically, the fitment of this to the Mk2 models had been intended by the engineers from the outset, but dropped as a cost-saving measure prior to entering production (though maintained as a necessary option for Police cars).  In practice, however, estate cars in particular suffered from accentuated body roll when unladen, and so the anti-roll bar was standardised on 2000 and 2.5PI estates from about mid-1970.  Similarly, early cars proved vulnerable to annoying driveline vibration problems and, in 1971 a modified differential nosepiece was introduced to overcome these by lowering the front of the final drive unit and thus eliminate inequalities in the working angles of the propshaft universal joints.

From that point in time onwards, many of the alterations introduced were simply to streamline production by standardising component specifications across more than one Triumph model, late 1971 seeing the introduction of revised cylinder block and head castings common to both 2000 and 2.5PI engines, 2000s also receiving new dome-top pistons producing a lower (8.8:1) compression ratio.  In November 1972 the manual gearbox was revised to accommodate the new Laycock J-Type overdrive then being adopted for use in other Triumph cars, overdrive being standardised as a fitment on manual transmission PIs from thence forwards.  At about the same time, engine specifications were revised yet again, 2.5PI units receiving a new camshaft profile, reduced-diameter exhaust valves, a recalibrated metering unit, new inlet manifolds with dual balance pipes and a revised throttle operating mechanism.

Many of these revisions were shared with the latest TR6 models, facilitating yet further rationalisation of production.  2000s also got the smaller exhaust valves and a revised cam profile, and would soon begin to be fitted with SU HS4 carburettors in place of the Stromberg units used since the inception of production, this latter change resulting from corporate BL policy which increasingly favoured the ‘in-house’ SU brand.  Taken as a whole, the alterations were claimed to help reduce harmful exhaust emissions, though a less desirable side-effect was a lowering of engine output, power being down to a quoted 84bhp for the 2000 and 120bhp in the case of the 2.5PI, with accompanying reductions in torque2. Maintaining the overall attractiveness of the product was not neglected, however, and at some point during the 1973 model year 2000 saloons finally received radial-ply tyres as standard, whilst the optional cloth upholstery progressively changed from brushed-nylon to a new broadcord material, which was shared with Triumph’s Dolomite models and used to cover the entire seating surface as opposed to the centre panels only.

Triumph 2.5 PI Police Car

The Triumph 2.5 PI was used by many police forces, including the Met.

One area where the product range diversified rather than being rationalised was in the supply of specialist variants for Police duties, and by the mid 1970s there existed quite an extensive range of options for this small but important market sector, serving both 2000 and 2.5PI models.  Many of these related to the inevitable upgrades of the electrical system required to support additional lights, sirens, public address systems, two-way radios, etc, and cars intended for traffic duties could also be equipped with an additional, specially calibrated speedometer located in a modified glovebox assembly.  Mechanical options largely consisted of stiffened suspension using estate car rear springs and front anti-roll bar, reinforced steel roadwheels (later standardised on normal production) and a Stag-derived heavy-duty gearbox.  In theory, powerplants remained basically standard, though it is believed that some forces had cars performance-tuned by independent specialists, whilst Triumph itself appears to have outshopped some early Police 2.5PIs with what were effectively TR6 engines.  The PI in particular was deservedly popular as a motorway patrol car, offering standards of accommodation and performance akin to those of the Jaguar XJ6 or Rover 3500 but with the benefit of rather lower purchase and running costs.  With the exception of certain cars supplied for ‘plain clothes’ duties, most Police Triumphs could be readily recognised even after demobilisation by the presence of two characteristic features; a zipped headlining to give access to the wiring serving the various roof-top lights, and small plain hubcaps ‘borrowed’ from the Triumph Toledo range which, whilst considerably less attractive than the standard items, were also rather less likely to come adrift during high-speed manoeuvres…

1974 Triumph Chicane

The South African-built Triumph Chicane - picture sourced from Moby's Site, a South African Classic Car resource.

Despite the proliferation of locally-produced alternatives, the big Triumph’s virtues continued to be appreciated in myriad overseas markets as well, some of which were served by local assembly plants manufacturing cars from completely knocked-down (CKD) kits supplied from Coventry.  This facilitated the adoption of minor modifications from the original design to suit local conditions and customer tastes.  In South Africa, demand for an automatic-transmission Triumph with more power than the 2000 but without the complexities of the fuel-injected cars saw carburetted versions of the 2.5PI starting to be assembled from about 1972, the first such cars reputedly being standard PIs fitted with carburettors and inlet manifolds taken straight from Triumph 2000 CKD kits. The Canley design team quickly applied its own experience with the non-injected US-market TR engines to finalise an official ‘2500 Carb’ specification, and a car using this engine but otherwise based on the South African-made 2000 Automatic was subsequently marketed there as the Triumph Chicane.  A similar product was introduced to the Australian market in 1973, though in that country sold as the Triumph 2500TC and available in both manual and automatic-transmission forms from the outset.

Had the course of history run differently, Triumph’s offerings for the early 1970s might have been supplemented by a range-topping Mk2 saloon fitted with the 3-litre V8 (PE188) engine used in the Stag.  As soon as Triumph came under the same umbrella as Rover, however, such a product was deemed to be too close to Rover’s own P6B 3500 models, and thoughts for powering the next generation of Triumph saloons would return to derivatives of the existing straight six, albeit thoroughly updated with a new overhead camshaft layout.  Officially, therefore, no ‘Triumph 3000’ was ever produced, though in practice some early development work on the Triumph V8 was undertaken using modified 2000s rather than the still-secret Stag, and a number of PE188 conversions were subsequently undertaken by Triumph on part-built production cars for senior company staff.  Once the Stag was announced, of course, it did not take long for people outside the factory to realise the potential of a ‘Stag saloon’, perhaps the best-known exponent of which was ‘Del’ Lines of Atlantic Garage, Weston-super-Mare.  Unlike the Canley-built cars which tended to retain standard 2000/2.5 production levels of trim and fittings, Lines’ approach was to complement the engine and transmission transplant with a variety of external and internal upgrades, typical features including aftermarket wheel/tyre combinations, Stag badging and front/rear wing marker lights, electric windows and Recaro reclining seats.  Despite practical and legal opposition from British Leyland, the Lines conversions attracted much favourable comment and something in excess of forty are thought to have been built in both saloon and estate car forms.

The Atlantic Garages Stag Estate

The Del Lines Atlantic Garages Stag Estate. This very car is now owned by Alan Chatterton of the Register and is undergoing restoration.

Another intriguing development was the conversion of a number of big Triumphs to permanent four-wheel drive by FF Developments of Coventry, using an arrangement similar to that already employed on the Jensen FF coupé and a small run of prototype Ford Zephyr MkIV Police cars.  Hoping to interest British Leyland in adopting the system for series production, in 1972 GKN (FF’s corporate parent) arranged for a pair of Triumph Stags to be converted as demonstrators, and two similarly-equipped 2.5PIs subsequently followed, along with a Stag-engined estate.  Some of the converted cars were also outfitted with the innovative Dunlop Maxaret anti-skid braking system, the combination providing formidable levels of roadholding on virtually any surface.  Although Triumph was sufficiently impressed as to honour the original warranty on any vehicles so-modified, the conversion process was both complex and expensive, taking around a month and increasing the cost of the finished vehicle by about 50%.  With few buyers having any appreciation of the benefits of all-wheel drive on high-performance road cars – the launch of the Audi Quattro would not take place for another eight years – these drawbacks heavily outweighed the undeniable advantages of the FF system, and it was not to be adopted for production use on Triumphs nor any other BLMC car.

next chapter

This article © Jonathan Lewis 2010
  1. From today’s perspective, it is difficult to be sure who became most disenchanted with the PI set-up: Triumph (whose engineers pointed to various quality failings in the Lucas-supplied equipment, some of which in turn could be attributed to BL-driven attempts to reduce production costs), Lucas (which became exasperated by BL’s failure to ensure that dealer personnel participated in the service training courses which it offered), or the buying public (too many of whom found dealers unwilling or unable to address service problems and accordingly tended to take subsequent business elsewhere…).
  2. Admittedly, the new readings were net figures to the more stringent DIN standards as opposed to the SAE (gross) calibration previously used, but most contemporary testers (and present-day owners) concur that the late 1972 changes resulted in a tangible loss of power in both saloon and TR applications.

Pages: 1 2