English Magazine
Motor 25th September 1971
Tony Curtis describes the new 15 and 17 coupes
Only two years ago Renault were thought of as a company producing cars mostly
of a practical, functional-even utilitarian -kind, cars like the R4, for
instance. That was before the introduction in October 1969 of the successful
Renault 12, as well styled a car as any in Europe. While in no way abandoning
their admirable functionalistic principles, the company now confirm their
additional interest in good looks with the introduction of the lS-17 range
of stylish fastback coupes, brief details of which were released earlier
this year. In so doing they complete a two-year transformation of their
public image in which they have shown themselves capable of being good artists
as well as sound designers. This rapid change demonstrates how quickly a
company can alter its emphasis and reputation if it really wants to, though
of course in this case the foresight and planning must go back many years.
The links with the Renault 12 are mechanical as well as stylistic, since
all four new cars are based on its platform and running gear, though clothed
in a completely new and very elegant fastback body which varies from model
to model in details of external appearance and equipment. The cheapest model
in the range is the 15TL which also inherits the four speed manual transmission
of the R12 and its 1289 cc pushrod engine, but in an uprated form developing
6 bhp more: 60 (net) bhp at 5500 rpm. Next there is the l5TS with a stronger
four-speed transmission coupled to a new, more powerful version of the 1565
cc Renault 16TS engine (with its hemispherical combustion chambers and inclined
valves) which develops 90 bhp at 5500 rpm. To cope with the extra power
the 15TS also has ventilated disc brakes at the front with drums at the
rear in place of the 15TL's ordinary disc /drum setup. Both these two cars-the
15TL and the 15TS-have relatively plain bodies distinguished by long side
windows behind the doors.
But the body of the mechanically identical 17TL-nest up in the range-has
been given a different and more flamboyant treatment around the rear quarters.
Behind each door a thickish pillar inclines rearwards to meet the roof and
give increased torsional rigidity while enclosing a fashionably louvred
triangle that covers a normal and openable window. In place of the rectangular
headlamps of the 15TL and 15TS are four circular halogen lamps.
At the top of the range is the 17TS with a five-speed gearbox and a more
powerful version still of the 1565 cc engine which with Bosch electronic
fuel injection develops 108 bhp at 6000 rpm-5 bhp less than the Renault
12 Gordini unit. The 17TS has disc brakes at the rear as well as the 17TL's
ventilated discs at the front. All models have lift-up tailgates for access
to the boot.
These cars will be on display at the Paris Show, not London, and will not
be available in the UK until the spring of 1972. Prices have not yet been
decided, therefore, but in France range from �1143 for the 15TL to
�1807 for the 17TS.
Bodywork and suspension
Based on the developed version of the Renault 12 platform, the bodies of
the 15-17 cars share the same 8ft wheelbase and have a track which is identical
in width for the 15TL but progressively increases to a 1 1/2 inch. excess
for the 17TS due to the fatter tyres fitted to the faster models. As for
the Renault 12 the structure is of monocoque form with bolt-on front wings
for easy repair. When there is a sunshine roof-an important factory-built
option for the 17TL and 17TS-it is framed by additional stiffening members
which more than compensate for any loss in torsional rigidity.
Inside this fastback body shell there is ample legroom in the two front
seats, moderate head and legroom in the rear and a surprisingly generous
boot. Access to this, Renault 16 style, is via a lift-up tailgate to which
a hinged part of the parcel shelf is attached. The R16 resemblance ends
there, for the rear seat is fixed, having behind it the R12's cross-bracing
structure into which the rear spring and damper loads are fed. On the 17TL
and 17TS models a spoiler runs across the lower part of the tailgate which
is claimed to increase the maximum speed by nearly 2 mph. All models except
the 15TL have a small power bulge in the bonnet to provide space for the
taller 1565 cc engine and especially for the fuel injection inlet manifolding
of the 17TS engine. The radiator grille surround and both front and rear
bumpers have a special energy absorbing design.
The suspension is essentially the same as that of the Renault 12 apart from
varying roll-bar thicknesses and spring rates to suit the differing performance
weight, (the 15TL is some 1.7 cwt. heavier than the 12), and distribution
of weight. At the front are lower wishbones and upper transverse links located
by forward facing reaction arms and supporting the coil springs and dampers
which thus are kept clear of the driveshafts. At the rear there is a dead
beam axle located by a central upper A-bracket and lower trailing arms.
As on the Renault 12 the geometry of this axle is designed to give increasing
roll understeer with increasing load and so to compensate for the rising
oversteer tendency with load that would otherwise exist. Similarly the relative
compliances of front suspension and steering have been arranged to stabilize
against sharp changes in attitude if the throttle is suddenly released when
cornering hard.
The R12's load-sensitive pressure-relief valve controlled by rear axle position
is also retained, and regulates the rear circuit of a braking system incorporating
a servo and a tandem master cylinder. The 15TL has a disc/drum setup, while
at the front the 15TS and 17TL have the ventilated discs of the Renault
12 Gordini; the 17TS in addition has plain discs at the rear in place of
drums.
Engines
To provide the extra power required the 1289 c.c. R12 engine of the base
R15TL model has modified combustion chambers - said by Renault to give an
extra 1.5 bhp - a compression ratio raised from 8.5:1 to 9.5:1, more camshaft
overlap and in place of the standard Solex carburettor a Weber instrument
breathing through a Renault 16TS type of air cleaner. The water heated inlet
manifold has been redesigned to take this carburettor and to give reduced
exhaust emissions, but the original exhaust manifold is retained. These
modifications raise the maximum power from 54 (net) bhp at 5250 rpm to 60
bhp at 5500 rpm; maximum torque is up from 69 lb. ft. at 3000 rpm to 71.9
1b. ft. at 35OOrpm.
Similarly the 1565 cc hemihead engine ~ powering the 15TS and 17TL is essentially
is the Renault 16TS unit tuned to give more power and based on the strengthened
~ Gordini block. Domed pistons help to j increase the compression ratio
from 8.6:1 to 9.25:1, the camshaft gives more overlap and longer opening
periods and again the heated inlet manifold has been redesigned to give
improved combustion and reduced exhaust emissions, while the exhaust manifold
remains the same. The power output is 90 (net) bhp at 5500 rpm compared
to the 16TS's 83 bhp at 5750 rpm while the maximum torque is up from 87-lb.
ft. at 3500 rpm to 90-lb. ft. at 3000 rpm.
The most powerful version of this engine, for the 17TS, has even more overlap,
a still higher compression ratio at 10.25:1 and Bosch electronic fuel injection
working in conjunction with a special Bosch distributor incorporating an
impulse generator. An oil cooler is fitted and there is an electrically
driven thermostatically controlled fan. In this state of tune the engine
develops 108 (net) bhp at 6000 rpm and 97.2 lb. ft. of torque at 5500 rpm.
Transmissions
The 15TL inherits the R12 transmission almost unchanged: four-speed floor
lever, manual gearbox, 6.7in. diameter clutch and 3.77:1 final drive ratio
giving 16.8 mph /1000 rpm on the 145-13 radial tyres fitted as standard.
For the 15TS and 17TL the R12 gearbox is retained but with the 7.9in. diameter
R16 clutch to cope with the extra power and a 3.55:1 final drive ratio giving
17.9 mph/1000 rpm in top on the 155-13 tyres. The 17TS model uses the Gordini
gearbox, again with floor-mounted lever, which is housed in the R12 casing
but with an alloy extension built on to its front end to house the additional
0.94:1 fifth gear which gives 19.1 mph /1000 rpm with the 3.77:1 final drive
and 165-13 tyres.
Equipment and fittings
Long famous for their seats, Renault have conducted considerable physiological
research into the design of those of the 15-17 range which are heavily contoured,
helping to give the cars an air of luxury appropriate to their performance
image. It is strengthened by the completeness of their equipment, which
includes such items as cigarette lighters and two-speed wipers. A central
console, a dock, a rev-counter and a heated rear screen are additional standard
fittings on the 17TL while electric window lifters are a further standard
fitting on the 17TS. Tinted glass and metallic paintwork are among the extras
available as well as the sunshine roof already mentioned.
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