Rover 3500 S

comparison with Triumph 2.5 PI

When the choice of a new car boils down to something in the executive saloon class around the £2,000 mark, there is nothing British other than a Ford Granada GXL, Vauxhall Ventora, Rover 3500 S or Triumph 2.5 PI. The Ford and the Vauxhall are built by American-owned companies, and for some reason which mostly escapes us, they do not carry as much prestige as the two British Leyland offerings. As a pair, therefore, the Rover and the Triumph come very much in the same class as each other. They are both quite compact saloons, around 15ft long, with performance in the bracket that gives them a top speed comfortably over 100 mph.

On price alone they are much less equal. In their cheapest forms there is a difference of £212 to be considered. Put power steering and automatic transmission on the Triumph and add a radio and most of the gap to the Rover price will have been swallowed up. On the other hand, power steering is equally desirable on the Rover and to get a cloth seat trim, which is a no-cost option on the Triumph, you must pay £24 extra. Both cars have heated rear windows and inertia-reel seat belts as standard.

Ideally, for comparison purposes, we should have used manual versions of both cars, with power steering, for our assessment in this test. Unfortunately the Triumph demonstrator was an automatic without power steering, which complicated the task but gave us some useful experience of a different version. For the performance table we have therefore used figures from previous tests since neither car has been modified since these went on record.

Description - Rover

Latest in Rover´s P6 series, the 3500 S made its debut in October 1971 - some three-and-a-half years after its automatic counterpart (the 3500). Body construction and suspension layouts closely follow the unique pattern pioneered by the 2000 model in 1963. It features a welded steel base unit to which are bolted the exterior body panels and mechanical components.

Front suspension is unusual in having transverse lower wishbones allied to longitudinal (leading) upper links. The latter actuate coil-type springs which abut against the rigid bulkhead portion of the base unit. Telescopic dampers and an anti-roll bar complete the arrangement.

An equally unconventional system is employed in the rear. Essentially a de Dion layout, it is unusual in having fixed-length drive shafts. The resultant track changes are taken care of by making the de Dion tube telescopic. This sliding tube construction enables fore-and-aft location to be effected by means of Watt linkages, one at each end. Each incorporates a large pressed-steel trailing link beneath the axle and a tubular leading link above it. The lower ones actuate coil springs and telescopic dampers.

Variable-ratio, cam-and-roller steering is employed, with power assistance as an optional extra. A non-adjustable leading "track rod" (matching the suspension´s upper link) forms a direct connection between the drop arm and the dajacent road wheel. The other wheel is steered by an adjustable transverse rod, a relay lever and a second longitudinal rod. A hydraulic damper is incorporated in the relay lever pivot.

Built under Buick license, the vee-eight engine employs die-cast alloy for the block and heads. Valves are overhead, actuated by hydraulic tappets, pushrods and rockers. There are five main bearings. Carburation is by a pair of the lastest-Type HIF 6 SUs. Thanks to a slightly more efficient exhaust system, peak power (152.5 bhp DIN at 5000 rpm) is some 5 bhp above that of the automatic version.

The diaphragm-spring clutch is hydraulically actuated and is counted to an extensively strengthened version of the gearbox employed in 2000 and 2000 TC models. A short propellor shaft continues from here to the final-drive unit, which features an extended pinion shaft enclosed in a rigid torque tube. The latter´s front end serves as one of the assembly´s three widely-separated mounting points; the remaining two are at the extremities of a cross-member bolted to the back of the final-drive housing. A short Panhard rod helps to resist cornering loads.

Disc brakes are employed for all four wheels, those at the rear being mounted inboard of the drive shafts. An in-line servo unit is fitted.

Description - Triumph

The 2.5 PI is directly descended from the Triumph 2000, which also made its debut at the 1963 Earls Court Show. Some four years later a ´stroked´ version of the 2000´s engine, equipped with Lucas petrol injection, was used to power the TR5. Triumph were quick to realise that they now had the ingredients for  a first-class sporting saloon. The outcome, a year later (October 1968), was the introduction of the 2.5 PI. Twelve months afterwards, both the 2.5 PI and the parent 2000 were superseded by much-improved Mk II versions.

Both cars (2000 and 2.5 PI) share the same basic body shell. Of orthodox all-welded construction, it features four large doors and generous glass area.

Front suspension is of the McPherson-strut type, employing coil springs. The forged-steel transverse arms are triangulated by means of diagonally-disposed leading links whose chassis-attachment points are designed to provide a controlled amount of compliance. There is no anti-roll bar.

Rear wheels are independently suspended on semi-trailing, cast-alloy arms. These pivot on diagonally-disposed pressed-steel members (one for each arm) whose inner ends are bolted to the nose of the final-drive unit. Bolted to the back of the latter is a third, transverse member (also a steel pressing). The whole assembly is resiliently mounted at four widely-separated points (the outer ends of the two diagonal members and the two extremeties of the transverse one). Coil springs and telescopic dampers complete the suspension arrangements. Hook-type joints are employed for the drive shafts, each of which has a splined coupling to accommodate changes in track.

Steering is by Alford and Alder rack-and-pinion. Integral power assistance is listed as an extra-cost option.

An in-line six of conventional design, the 2.5 PI´s power unit employs cast iron for the block and head. The crankshaft (also a casting) runs in four main bearings. Valves are overhead, actuated by pushrods and rockers.

The 2.5 PI is unusual in having the Mk II petrol injection system. With its six individual inlet tracts, each with its own throttle-plate, the set-up is conducive to excellent breathing. The result, despite the use of mild 2000 camshaft (as distinct from the sportier pattern employed in TR models), is an impressive 132 bhp DIN at 5450 rpm. More important, the torque curve peaks at a modest 2000 rpm (153 lb ft).

In basic form, the car has a hydraulically-actuated diaphragm-spring clutch driving an all-synchromesh gearbox. Listed as an extra-cost option is a Laycock-de Normanville overdrive. Yet another option is the Borg Warner model 35 automatic transmission. In all three cases, the final-drive unit has a ratio of 3.45-to-1.

Brakes are disc at the front, drum at the rear. A direct-acting servo is used.

Performance - Rover 3500 S

Never has a car been so transformed by the adoption of a manual transmission in place of automatic as the Rover 3500. As if by magic the whole car has been endowed with a new sporting character which puts it much more in the class of something like a BMW. Because the vee-8 engine is largely built of aluminium the whole car weighs only 135 lb more than a Rover 2000 TC and it has all the long-legged high-geared feeling of the four-cylinder versions, plus a lot more urge with a tremendously eager response to the throttle. The vee-8 is also much smoother and more refined than the four, to the extent of making the 3500 S feel like a turbine car in comparison.

Starting calls for generous use of the manual choke when cold and we found the knob could be pushed back a long time before the warning tell-tale came on as a reminder that normal engine temperature had been reached. There were no flatspots anywhere in the range and the cold-start drive-away characteristics were excellent.

From a standing start the 3500 S rockets off to reach 60 mph in just over 9 sec and then goes on to clock 100 mph in under 30 sec. Top gear flexibility is remarkable, the car pulling quite strongly from only 10 mph in top.

Clutch pedal effort is a heavy 44 lb. and the gearbox was notchy and stiff to use, with a non-too-positive and rather rubbery feel about the shift mechanism. Ratios, though, are well spaced and high, with third good for 90 mph and second capable of nearly 60 mph.

Performance - Triumph 2.5 PI

The petrol injection version of the Triumph siy-cylinder saloon has been developed very much with performance in mind. The extra half-litre of capacity and a sporty camshaft combine with the injection characteristics to make the engine very like that fitted to the TR6 two-seater. There is rather less peak power, but a better spread of torque in the middle of the range.

To judge from recent correspondence in Autocar, owners often have trouble with the injection engine. During the course of this test, which admittedly was in mild weather, we found the engine always fired first try as long as the manual choke knob was pulled right out to the limit of its travel. Almost as soon as the engine was running, the control could be pushed back, and this practice was essential to avoid a very sooty exhaust trail and spark plug fouling. Once the car had been parked for over an hour, some use of the choke was again required for easy starting, but only momentarily.

The manual gearbox on this model normally has quite a light action but suffers from unpleasant baulking if the synchromesh is required to do much work. The clutch effort required (30lb) is low, but a badly designed throttle linkage gives a jerky take-up which makes traffic driving uncomfortable for passengers. Generally speaking the automatic option is well suited to the car, apart from a tendency for the creep rate to vary with fluctuations in idling speed (a characteristic of the injection equipment).

Performance of the manual PI is brisk, with a 0 to 60 mph time of 11.5 sec recorded and 0 to 100 mph possible in just over 40 sec.

Performance Differences

There is no doubt that the Rover is by far the quicker car, as well it should be with an extra 20 bhp and 50lb ft of torque. In terms of weight, its built-up construction gives it a 2cwt handicap, but many will prefer the better ride and solidarity this brings with it.

On top speed alone, the Rover has a 14 mph advantage over the Triumph although both can be cruised happily at 100 mph. In fact, the addition of overdrive to the Triumph (not available on the Rover) makes its motorway behaviour the more restful of the two.

Apart from the obvious differences in the standing-start acceleration times (Rover 2.4 sec quicker to 60 mph, and 13 sec quicker to 100 mph) the Rover is much more flexible at low speeds and a lot more eager in the 70 mph plus brackets. In the Triumph you know you are driving a tuned engine, whereas in the Rover the comparative silence and smoothness add considerably to the refinement and could fool you into thinking that it is a de-rated unit.

Fuel consumption

Fuel consumption, among other things, is a function of vehicle weight, so it is only to be expected that the Triumph should prove the more economical of the two. Differences, though, are slight, the Rover returning 20.8 mpg overall, against the Triumph´s 21.8 mpg. At a steady motorway 70 mph the figures are 24.7 mpg for the Rover and 26.3 mpg for the Triumph. In automatic form both cars drop to around 18 mpg.

Brakes

Whilst there is little to choose between the two cars in terms of ultimate stopping power, the Rover requires appreciably more pedal effort during the course of normal check-braking. In addition, its brakes are inclined to squeal and ´wire-brush´ when hot. Neither model suffers from fade problems. Another good point concerns the effectiveness of the parking brakes (despite the use of rear discs on the Rover).

Ride and Handling

Even now, nine years after its inception, Rover´s unconventional layout is able to hold its own with most competition. Road noise insulation is good, there being little bump-thumping on any but the roughest of surfaces. Some of the coarser asphalt roads generate a certain amount of background hum, but this is never troublesome.

Even more impressive is the quality of the ride itself. The car has a pleasantly taut feel, yet the suspension copes with rough going in a most pleasing way. There is never any float or pitch, but hard braking does result in considerable dive.

Steering response is good, especially near the straight-ahead position. Moderately hard cornering results in considerable body roll and a fair amount of understeer, but the latter is effectively camouflaged by power assistance. Fiercer treatment causes the balance to revert towards neutral, but is accompanied by a great deal of tyre squeal.

The Triumph´s more conventional layout provides even better road-noise insulation, but the ride quality is a trifle less impressive. Our main criticism concerns a tendency towards pitching over certain short-wave undulations. In addition, there is noticeable rear end ´squat´ under hard acceleration, but this causes no discomfort.

Despite fairly low gearing, the Triumph´s unassisted steering requires considerable effort. Without doubt, many buyers will want the optional power system. This apart, the car handles extremely well. Cornering ability is good and there is relatively little roll. Undoubtedly, it is a much more ´chuckable´ car than the Rover. One of the penalties associated with this is a slightly less stable feel at high speeds. Another oddity is a tendency to veer to the right under hard acceleration and to the left when lifting off.

Noise

In the main, both cars are quiet and possess a distinct air of refinement. Road-noise insulation is good and the wind noise is moderate at all but the highest speeds (over 100 mph).

Almost inevitably, the Rover´s vee-eight engine with oversquare dimensions give it a marked advantage. Apart from a subdued burble from the exhaust, the unit does little to advertise its presence.

At low and medium speeds, the Triumph is surprisingly quiet, too. When driven hard, on the other hand, induction and exhaust notes blend to produce the kind of noise regarded by some as an essential part of a sporting model.

Fittings and Furniture - Rover

It is now two years since the Rover P6 was revised in detail, a new facia and instruments being the most obvious improvements. The current layout is excellent, once a driver new to the car has learnt to find his way around the unconventional controls.

In front of the driver is a panel containing large and very legible speedometer and rev counter, flanked on the left by an oil pressure gauge and voltmeter combined, and on the right by the fuel gauge and temperature gauge sharing a similar round dial. A pair of stalks, one each side of the column, control indicators, horn and lamps with rotary master lamps and map light switches on a central panel. This panel also contains the wiper and washer switch (with variable delay intermittent wiping provision), hazard warning control and interior lamps switch which also operates a neat map reading light over the passenger´s knees. On each side of the centre radio speaker grille are hooked knobs, the one on the left operating a 2 1/2-gal fuel reserve and that on the right controlling cold start mixture.

Each side of the facia in front of the occupants knees is a deep vertical pocket with padded lid and small cylinder lock. Above the facia rail in line with the instrument binnacle is a useful shelf.

On the 3500 S the seats are trimmed in Ambla ventilated pvc instead of the leather which is standard on the automatic 3500. For £24 extra you can specify leather or a durable brushed nylon cloth. We found there was too much lumbar support on the test car and not enough lateral location to withstand the considerable roll angles which could be induced during fast cornering. The back seat is shaped for only two, with insufficient padding in the centre even for emergency use. The Rover is therefore strictly a four-seater. Rear doors are rather narrow, making it difficult to clamber in over the deep sills and legroom is severely limited. There are no child locks on the rear doors.

By medium saloon-car standards the boot of the Rover is both short and shallow in parts. The spare wheel standing on the left taking up much of the precious width as well. For an extra £18 a kit is available for mounting the spare wheel on top of the boot lid, but it then blocks rear vision and spoils the counterbalance of the lid.

Fittings and Furniture - Triumph

Three years ago, the Mk II Triumphs were announced and these were much improved in many ways. The facia, which was really designed for the Stag but appeared on the 2000 and 2.5 PI first, is a fine example of how to lay out an instrument panel. In front of the driver are a matching speedometer and rev counter with an eight-way warning lamp cluster in between, and three supplementary dials on the outboard edges. A stalk on the right of the column works the indicators, headlamps flashers and horn in the usual way, while a matching one on the left operates two-speed wipers and electric washers with a spring-loaded position for single flick wiping.

In front of the passenger is a locking glove box and under the facia each side a useful parcels shelf. Seats are trimmed in pvc or cloth for the same price and we found them comfortable and well supporting. In the back there is a central folding armrest and a very reasonable amount of legroom. Rear doors have no childproof locks.

Apart from a high rear sill the Triumph´s luggage boot is large and convenient to use. The spare wheel is out of the way under the floor.

Fittings and Furniture - Differences

As far as the driver is concerned, this pair of cars appear very similar. Both cars have well laid out instruments and controls with large, easy-to-read dials and no owner would get confused once he had become familiar with one or the other. The unconventional arrangement of stalks on the Rover (pull right-hand lever to sound horn) continued to annoy us and we wonder how long Rover can stick to this idiosyncrasy.

The seats in the Rover are not as comfortable as those in the Triumph and there is room for only two in the back. As far as legroom is concerned the Triumph is much better, its extra 2 1/2-in. of wheelbase paying handsome dividends here. Neither car has childproof door locks, a mean omission on cars which are meant to be for family use.

Both cars have excellent heating and ventilation systems, the Triumph having four adjustable fresh-air outlets and the Rover two, unusually placed directly in front of the driver´s and passenger´s faces. The Rover has opening quarter-vents front and rear, while the Triumph has them in the front only.

For luggage, the Triumph has a 15cu.ft boot compared with 16 1/4cu.ft for the Rover, but when it comes to actual dimensions the Triumph is about 31in. long by between 15 and 20in. high by 54in. wide for most of its length. Rover´s dimensions are 32in. long by between 15 and 26in. high by only 36in. wide.

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Personal opinion

As is so often the case in these double tests I would really like to combine the best features of both cars into one ideal model. I would want to keep the Rover engine and power train but fit it into the Triumph body. In the Rover I found the scuttle and body sides much too high to see over comfortably and I did not like its excessive roll on corners and peculiar handling characteristics. If I were to be chaffeur driven and have to use the back seat, it would definitely be the Triumph for me.

Because it is so effortless and refined, my first instrinct is to choose the Rover but I really feel the shortcomings would get me down in the end and cause me to change my mind. By a very close margin therefore I would choose the Triumph with power steering and overdrive. Any doubts I may have had about the reliability of the petrol injection equipment now been dispelled by our long-term experience of a Mk I 2.5 PI owned by the company. As a family man I cannot understand why both manufacturers fail to fit childproof locks to the rear doors (something you get these days even on a Ford Escort or Morris Marina). The release levers do not override the sill pips, however, so I suppose the answer is to unscrew and remove these each time you carry children in the back.

Georffrey Howard.

Personal opinion

Were I shopping for a medium-sized (and medium-priced) British saloon, both these models would be on my short list. Indeed, their only rival would be the Ford Granada, but that is another story.

Both cars are derived from basically nine-year-old designs. Even so, the Triumph´s specification has much in common with that of newer and more expensive rivals. Although radically different, the Rover is also able to hold its own on most counts.

The biggest contrasts between the two concern styling and luggage capacity. With the benefit of an extensive facelift some three years ago, the Triumph has much the more pleasing lines. Among its practical advantages are an appreciably lower waistline, clearly defined corners (from the driving seat) and easier passenger access. Spare wheel storage beneath the boot´s false floor makes for greater area and a more useable shape. Unlike the Rover, though, the Triumph´s boot has an awkwardly high sill.

Where ride and handling are concerned, there isn´t a great deal to choose. The Rover has a marginally better ride and feels a little more stable at high speeds. On the other hand, the Triumph rolls appreciably less and is the more handleable car on winding roads.

Predictably, I prefer the Rover´s power-assisted steering (an extra-cost option), but past experience suggests that the Triumph´s rack-and-pinion layout is equally good (possibly even better) in power-assisted form.

The optional automatic transmission robbed the Triumph of much of its sparkle, thereby making comparisons somewhat meaningless. Although the Rover would have a performance advantage in any event, a manual 2.5 PI has a distinctly sporting feel and performs very adequately.

Choosing would be a formidable task. I love the Rover´s silky-smooth engine and effortless performance, but prefer the Triumph´s low waistline and large boot. Other points in the Triumph´s favour are its atractively-styled interior and no-cost option of brushed-nylon upholstery.

Ignoring price, I might well settle for the Rover in power-steering form. However, a Triumph with power-steering and overdrive shows a saving of over £160 - almost enough for a year´s fuel. This would just tip the scales in its favour.

David Thomas

Autocar / UK October 1972

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