The Fuel-Injection Triumph TR5 PI
On October 3rd last year Standard-Triumph announced the latest model in their successful range of TR sports cars, this one being christened the Triumph TR5 PI. Using the same shell as the previous TR4, the new model also incorporated a much improved version of the independent rear suspension system fitted on the earlier TR4A, and was powered by a 2½-litre version of the Company’s successful 2-litre 6-cylinder engine. An interesting innovation, however, was the use of a Lucas fuel-injection system, making this the first British production car to be fitted with this type of induction system as standard.
We decided to delay a road test of the car until after the initial wave of enthusiasm had died down, and a Valencia blue TR5 PI “soft-top” was finally delivered for a fortnight’s road testing at the start of July. At that time the International Gulf London Rally was taking place and, as the route formed a huge figure of eight, starting and finishing in Manchester and taking in Wales, the West Country, the Midlands, the north-east coast and much of southern Scotland, I decided to follow it in the Triumph. The result was a rather exhausting total of 2,084 miles covered in four days over mainly rural byways, and this proved an extremely enlightening test of this very pleasant big-engined sports car.
The TR5 itself is, at first sight, one of these old cars with a new name which far too many manufacturers seem to be turning out nowadays. But the TR4 shell has an attractive aggressive look about it, so perhaps this is no bad thing, and only detail alterations have been made to the interior and exterior trim. Revised stainless steel side flashes, a new-style radiator grille, protruding indicator repeater-cum-sidelights, twin reversing lights, TR5 and “2500” badges, and rather silly “custom” wheel trims looking like the Rubery Owen pressed steel wheels fitted to the Rover 3.5 and Cortina 1600E, all serve to make this new model that much different.
Inside, more changes have been made, and the test car was upholstered in fawn Ambla material, the two well-shaped and deeply padded bucket seats having non-reclining backs although endowed with a fair amount of fore-and-aft adjustment. The dash panel was a rather cheap-looking affair of dull-finished wood with a prominent join in the middle, but carried a large Smiths tachometer and speedometer well in view dead ahead of the driver, with temperature and oil-pressure gauges also well-placed left of centre and fuel gauge and ammeter between them and the tachometer. Dash panel lighting was controlled by a too-large rheostat knob mounted over the join in the panelling. Warning lights were supplied for oil pressure, ignition, high beam and indicators, two in the foot of each of the large instruments. Right-hand rocker switches operated the 2-speed wipers and electric windscreen washer, and a cowled console over the transmission tunnel carried pull-out knobs controlling air distribution (this one carrying a steering column and arrows symbol which made it look like the non-existent steering-column rake adjustment), 2-speed fan, heater temperature and “choke” for the fuel injection system’s cold-starting arrangement. Two face-level fresh-air vents are provided with centre twist flow regulators, end are fed from an inside-controlled scuttle intake.
The large pedals were slightly offset in the tapering footwell, but seemed well-spaced, while a foot dip-switch was mounted to the left of and above the clutch, which was not a good point, modern dip-stalks being much more simple to use—and find! Steering-column stalks in this case controlled the side- and headlights, and the indicators, with a central horn push sunk into the steering boss of the pleasant padded-spoke, leather-rimmed steering wheel.
The chunky gear-lever stood in a black leather gaiter on the transmission tunnel, placed handily quite close to the steering-wheel rim, with the hand-brake, clad in a fawn Ambla gaiter, just behind it and down beside the driver’s hip. The lock-down seats tipped forward to give access to the small carpeted shelf in the rear of the cockpit, which could jokingly be described as an occasional seat but which formed a useful baggage space. Further stowage was offered by stretch pockets in the door trims and by a small lockable glove compartment on the passenger’s side of the dash panel. The boot itself is rather small, with the large spare wheel stowed beneath the floor. A Radiomobile wireless was fitted in the centre console between the footwells. A small ashtray was located on top of the heavily padded facia, and the crash padding is augmented by a collapsible steering column and lap and diagonal Britax seat belts.
The test car was a soft-top, and the hood is one of the best of its type that I have seen. It is non-detachable, folding down and taking up some of that useful space behind the seats but, with rigid channel sections above each wind-up side window, Velcro nylon press fastening along the channels and lever tensioning at the front, proved almost totally flap-free and extremely weather-proof; the days of fold-up celluloid sidescreens certainly seem to be over. . .
The TR5 has had its chassis altered in detail only to accept the long 2,498-c.c. 6-cylinder engine, which has under-square bore and stroke dimensions of 74.7 mm. x 95 mm. and a compression ratio of 9.5 to 1, demanding 5-star fuel. The fuel-injection system feeds from an 11¼-gallon tank with spring-loaded central filler cap, and consists of a special filter and an electric fuel pump feeding at 100 lb. p.s.i. to a rotor metering unit mounted low on the near side of the very accessible engine. The metering unit is driven at one-half engine speed, and delivers pulses of fuel to each downstream inlet as it is required, the fuel quantity being determined by a mixture-control device which is operated by manifold pressure. Any excess is returned to the tank from the filter and metering unit, and separate inlet manifolds with individual throttle butterflies are used.
With this system, the TR5’s engine produces a quoted 150 b.h.p. at 5,500 r.p.m. Transmission is through an 8½-in. diameter diaphragm spring clutch to an all-synchromesh four forward and reverse gearbox, with ratios of 3.14, 2.01, 1.33 and 1.0 to 1 in the forward gears and 3:22 to 1 in reverse.
Since Standard-Triumph adopted all-independent suspension in their TR range (on the TR4A), they have come in for a lot of adverse criticism. Consequently the similar independent rear suspension used on the TR5 has been stiffened considerably to improve roadholding, and this certainly seems to have worked. The system uses semi-trailing arms and co-axial coil-spring/damper units, and the whole thing is hung on a rubber-bushed sub-frame. At the front, upper and lower wishbones are used with, again, coil-springs as the suspension medium.
On the road, the TR took quite a bit of getting used to. At first the bonnet and wings seemed completely invisible from the driver’s seat, and I was reduced to stuffing my jacket down the non-adjustable seat back to sit up and forward a little more to see. But after a few more miles I soon became acclimatised. and found that the car could be aimed quite accurately through its fairly light and rather dead rack-and-pinion steering by sighting along the “power bulge” in the bonnet. (This is a legacy from TR4 days, and with fuel injection instead of carburetters is not really necessary.)
The clutch had a long travel, but was sensitive and eventually proved very quick to use, and the gearbox, which seemed stiff and notchy, changed ratios quickly once I had got used to their placings and individual idiosyncrasies; 2nd, for example, had rather weak synchromesh when trying to change up quickly, and really this is not a very good unit at all. But I should say that I feel a difficult gearbox is half the fun in a real sports car, and unbeatable synchromesh would be a loss of character.
A large servo is included in the braking system, which has a tandem master cylinder operating front 10 7/8 in. discs and rear 9 in. x 1¾ in. drums independently, and moderate pedal pressure was all that was necessary for a most impressive stop—I took to wearing my seat belt!
One peculiarity of this particular car was a slightly sticky throttle and, with fuel injection, throttle response was so instant that this gave rise to some kangaroo-style motoring for a little while. Power seemed to be either on or off, with no shades of grey in-between, but with some practice and a lot of concentration it became possible to “feather” the throttle over the point where it stuck slightly and things were then smoothed-up considerably. Smoothness, in fact, is one of the TR5’s keynotes, for the 6-cylinder engine is silky smooth through its rev. range, the muffled exhaust note hardening at around 3,000 r.p.m., at which point the power really began to come in, although there is plenty of torque throughout the range, the muffled exhaust note hardening at around 3,000 r.p.m., at which point the power really began to come in, although there is plenty of torque throughout the range.
Leaving Manchester Airport at the start of the London Rally, we soon ran into torrential rain, and in these flooded conditions the Michelin XAS tyres showed up excellently, draining so well that we never had a nasty moment with aquaplaning, which most other people seemed to be experiencing. In just damp conditions though, with a slick road surface, they did tend to let go, and with the car’s inbuilt tendency towards understeer it was possible to slide into corners with the front wheels on more lock than necessary, but with 150 b.h.p. driving the rear wheels these could easily be unstuck to bring the car round and point it out of the corner before “feathering” the sticky throttle in again to accelerate gently away. Under heavy braking also it was possible to lock the front wheels, but cadence braking, naturally, minimised the effect.
With the extremely changeable weather conditions we encountered the hood was raised and lowered several times, a simple and quick operation, but we did find that the separate hood cover provided suffered from rather brittle moulded plastic popper fittings. These have a very narrow moulded neck in them, and with very little effort three of them were snapped off, leaving the cover to flap slightly. The hood itself, however, was virtually faultless, giving plenty of headroom and excellent all-round visibility. The windscreen pillars were also sufficiently slender to eradicate any obvious blind spot, but the wipers missed a patch near to the off-side pillar on the curved screen, and after a few miles this became so mud-encrusted as to present a serious problem. The wipers also, incidentally, lifted from their normal parked position at speed, and were rather annoying as this made it difficult to sight on the raised near-side wing.
Under hard acceleration the suspension is soft enough to allow the nose to cock up in the air and the tail to sit down, and gear-changes were accompanied by a sharp dip of the nose, allowing a glimpse of the road ahead, before the tail sat down again and the TR5 was bounding away towards the horizon. This long nose also got in the way on some of the blind crests in the Welsh and Scottish lanes, and this usually meant the passenger standing up or the driver leaning out of his door to-see which way the road went up ahead.
But apart from these freakish situations the TR5 proved itself very comfortable and quick long-distance transport, and even without reclining seats was a very easy car to sleep in—which is something you can’t say about many sports cars.
A peculiar trouble struck the twin-tone horns, which suddenly began to operate at less than half-power, emitting a weak “threep”. This developed until it happened every time we hit a bump in the road, and the ammeter showed a huge charge at the same time! Finally a bump near Wark in Northumberland left the horns on permanently, a broken tag in one connector was found, and things were put right. The headlamp flasher also ceased functioning.
Most of our 2,084-mile total in those four days was put in over some pretty rough country roads, and while it was rather deflected at speed by the bumps, the TR generally rode them well, being stiffly, but by no means solidly, suspended. The only worry with the ground clearance occurred when a downhill slope of about 1-in-15 became an uphill climb of about 1-in-4 under a bridge. At 60 m.p.h. or so, this dip put a large dent in the silencer, but for most practical purposes ground clearance is more than sufficient, and even this mighty wallop did not hole the silencer.
Tickover was at first lumpy and then failed altogether, a lot of heeling-and-toeing being necessary to keep the engine running at rest. The front disc brakes tended to pick up grit readily and rub and squeal, but a dab usually cleared this and reasonably silent travel was resumed.
The bulbous reversing lights were flexibly mounted an rubber, the offside one filling with water during our chase of the Rally, but still operating perfectly—which must prove something. . . .
When we took our acceleration figures a high and very changeable wind was blowing, and this may explain why our figures were slightly better than those which the manufacturers claim.
Fuel consumption figures for the entire run totalled 21.8 m.p.g., and 3½ pints of oil were added to the engine. This trailed quite a bit of smoke from the twin tail-pipes at times, but the engine itself stayed very clean. Incidentally oil pressure was 60 lb. psi. at any maintained road speed over about 40 m.p.h., and the engine ran cool enough for the radiator to be touchable at all times. A plastic overflow catch tank was provided and this was always full.
After that hectic week chasing the Gulf London Rally, a further 778.1 miles were put in on the car before it was returned, rather sadly (and rather muddy), to Standard-Triumph. It is a sports can with a mixed personality. In town it burbles along gently in top at anything down to about 20 m.p.h., to accelerate cleanly away when required without changing down. It is quiet, smooth and comfortable at these speeds, and then out on the open road, or on a twisty country lane in particular, it is all thunder and fury, the engine swinging through its smooth rev. range rapidly and spinning the wheels under heavy-footed acceleration away from tight corners. In town 25 m.p.g. or more is possible, while on very fast sections it can drop to as low as 17 m.p.g., but the figure returned during our hard chase up and down the country was very good for a 2½-litre sporting “six”. The TR5 has its imperfections, but is a vast improvement over the immediately preceding TR4A, and is a most desirable sports car, being one of the few real “man’s cars” remaining, for it is very fast, quite heavy and a handful if it should break loose, but still sufficiently sophisticated to be well worth the £1,212 8s. 11d. asked for the soft-top version tested.
D. C. N.
TR5 PI Specification
Engine : Six cylinders, 74.7 mm. x 95 mm. (2,498 c.c.). Pushrod operated overhead valves, 9.5-to-1 compression ratio, 150 b.h.p. at 5,500 r.p.m., 164.2 lb. ft. (quoted as 1,970 lb. in.) torque at 3,500 r.p.m.
Gear ratios : 1st, 3.14 to 1; 2nd, 2.01 to 1; 3rd, 1.33 to 1; top, 1.0 to 1; reverse, 3.22 to 1.
Tyres : Michelin XAS on 4½J 15-in. steel disc wheels.
Weight : 19¼ cwt. dry. 24½ cwt. maximum.
Steering ratio : 3¼ turns lock-to-lock.
Fuel capacity : 11¼ gallons.
Wheelbase : 7 ft. 4 in.
Dimensions : 12 ft. 9 5/8 in. x 4 ft. 10 in. x 4 ft. 2 in. (hood up).
Prices : £1,212 8s. 1d. (soft-top with p.t.), or £1,255 9s. 4d. (hard-top with p.t.).
Makers : Standard -Triumph Ltd., Coventry.