English Magazine
Autocar, 23rd September 1971
FOR Renault the idea of a stylish two-door coupe died with the Caravelle.
But that was some time ago: today such cars are taking an ever-larger share
of the market as the car-owning middle class looks for something more than
basic transport. With cars like the Ford Capri, the Opel Manta and the
Fiat 124 Coupe selling really well in the Common Market countries, it was
inevitable that Renault would soon follow suit. They have now done so, and
the only surprise is the thoroughness of the operation, based on no fewer
than four versions of their new car: the 15TL, 15TS, 17TL and 17TS.
The 15-17 range is in no sense a panic measure brought about by the advent
of the Capri or Manta Development started over three years ago. This is
not really surprising - if the market research department of any major car
manufacturer is doing its lob properly it is bound to come up with (more
or less the same answers as everybody else�s departments.
Differences are more likely to arise in the way the engineers interpret
the findings. Probably Renault would have liked to get the 15/17 going sooner,
but until the supply of the 4 and 16 something like matched the demand,
and the 6 and 12 had been well and truly launched, it would have been unwise
to go any farther.
Same or Different?
Is the Renault 15 a different car from the 17? Not really. There are differences
but the use of a separate designation is a bit hard to justify. In Renault
parlance the 15 is a saloon and the 17 is a coupe, but both use the same
body shell. The only basic differences are that the 15 has full-length side
windows aft of the doors, while the 17 has abbreviated windows and stylized
rear quarter
grilles and the 15 has rectangular headlamps, while the 17 has a four-lamp
tungsten-halogen system.
There is in fact, much which all four models have in common. They not only
share the same body shell but are all based on the Renault 12 floorpan and
suspension, and basic running gear. This means that they are unique in this
class (unless one counts the Peugeot 204 and 304 coupes) in having front
wheel drive.
Renault rings the changes between the four models by fitting different power
units. The 15TL, 'baby' of the range is powered by a slightly tuned version
of the 1,289 c.c. Renault 12 engine of which more later The 15TS is given
a substantial power bonus in the form of a tuned version of the 1,565 c.c.
engine from the Renault 16TS. The same power unit is also fitted to the
17TL, so that these two models are mechanically identical. To justify the
different designation one has to look at the styling changes already mentioned
and to the 17�s higher equipment standard - with a heated rear window,
centre console rev counter and clock as standard and electric windows as
an option.
The 17TS naturally is more powerful still. Since the 1565 c. c. engine is
the biggest Renault make at the moment, there was no alternative but to
tune it even more. It proved impossible to do this by conventional means
without failing the new European exhaust emission standards, and so recourse
was had to electronic fuel injection. This metered fuel accurately enough
to meet the standards even with the high compression and wide camshaft overlap
of the 17TS engine.
Engines and Transmissions
Compared with the Renault 12 engine, the 1.289 c.c. unit in the 15TL has
a considerably higher compression ratio, of 9.5 rather than 8.5 to one.
A slightly wilder camshaft is used (the timing is 22-62-65-25), and a twin-choke
Weber 32DIR carburettor supplies the mixture. The actual increase in DIN
power is 6 bhp, of which a slight redesign of the combustion chambers themselves
accounts for 1.5 bhp. Torque is also slightly higher, but peak power and
torque speeds are both raised. Standard Renault 12 clutch and transmission
are used unchanged in the 15TL.
The 1,565 c.c. power unit used in the 15TS and 17TL is a much more hybrid
engine. Basically it is the 16TS, but with a number of important changes.
The cylinder block is that of he 12 Gordini rather than the 16. There are
few changes at the top end, but domed pistons are fitted to bring the compression
ratio up from 8.6 to 9.25 to one. Breathing is improved by using a camshaft
with 24-68-68-24 timing, and a larger fan is fitted to ensure sufficient
cooling in all conditions. With the aid of these changes, the DIN power
goes up from 83 to 90 bhp, despite which the peak comes at lower speed (5,500
instead of 5,750 rpm). There is a small increase in torque also, again with
a lower peak speed. On paper, at least, it appears to be a remarkable piece
of tuning. To accept the greater output, the transmission is also something
of a hybrid. The Renault 12 gearbox is used, teamed up with the 16's clutch
and 12 Gordini drive shafts.
The 17TS engine owes more to the 12 Gordini than to the 16TS in some ways.
Indeed, it now becomes clear that the 12 Gordini was not just a boy-racer
version of the ordinary Renault 12 but something of a mechanical test-bed
for several features of the 15 and 17. It used the high (10.25) compression
ratio and wide-overlap (40-72-72-40) camshaft and lacked only the electronic
injection, built-in oil cooler and electric fan, which are standard 17TS
features. In 17TS form, the engine produces a remarkable 108 bhp (DIN),
but cannot help being a slightly 'cammy' power unit with peak torque up
at 5,500rpm.
The 17TS transmission, like that of the 12 Gordini, has five forward speeds,
with the fifth gear housed in a light alloy cover added to the front of
the basic gearbox. A larger clutch is used, and the final drive reverts
to the Renault 12 ratio of 3.77 compared with 3.55 for the 15TS and 17TL.
The gear ratios are relatively close, so what when one considers overall
gearing, the fourth gear falls below top in the 17TL, while fifth gear is
higher but still modest at 19.1 mph per 1,000 rpm.
Suspension and brakes
One of the most surprising things about the new cars, perhaps, is how little
the Renault 12 suspension has been changed to meet the new application.
As before, double wishbones are used at the front and a dead axle at the
rear, the latter located by two trailing arms and an A-bracket. The same
units are used on the 15 and 17. The 15TL employs the Renault 12 suspension
absolutely unchanged, while the other three versions differ only in having
thicker anti-roll bars front and rear.
Rack and pinion steering is used, with a reduction ratio of 20 to one. The
rack is set well back behind the centres of the front wheels, and its mounting
is notable in that the height may be adjusted by turning graduated eccentrics,
so altering the steering geometry.
Renault have always endowed their cars with generous brakes-the Renault
8 with its very early all-disc system comes to mind and there is nothing
surprising in finding that the higher-powered models in the 15/17 range
sport ventilated front disc brakes. Only the 15TL has plain discs at the
front, backed up by drums on the rear wheels. The 15TS and 17TL use the
ventilated front discs. While the 17TS uses them in conjunction with plain
discs on the back. The dual-circuit system, with servo assistance as standard,
incorporates a load-sensing valve in the rear brake line to prevent premature
locking of the back wheels.
Body features
Although the new cars are based on the well-tried Renault 12, care had to
be taken that the very wide door openings did not weaken the structure.
Integral chassis members were added to the body shell to ensure that sufficient
rigidity was achieved, while the door hinges themselves were the subject
of very careful design. The 17s are available with a sunroof option, and
it was found possible to strengthen the siderails of the sliding roof to
add to the beam stiffness of the car.
A good deal of work also went into the bumper design, and the new Renaults
follow transatlantic practice to some extent by having a bumper frame completely
surrounding the nose opening and blending into the lines of the bodywork.
The frame is collapsible to some extent, and is mounted on brackets which
can also bend to absorb higher impact loads, At the back of the car, the
bumper consists of a polyester moulding.
There is no boot lid as such, for the 15 and 17 follow the lead of some
earlier Renaults in having a lift-up tailgate, with part of the rear parcels
shelf rising in sympathy. On the Renault 17s, the rear edge of the tailgate
is provided with a small spoiler which Renault reckon to be worth 3 mph
on the maximum speed by delaying flow breakaway over the back window.
Production prospects
Following Renault's usual principle, initial production of the 15 and 17
will be for the home market only, until supplies have been built up to the
sort of level that can satisfy export demand. It is anticipated that this
will see the first cars going abroad in the spring of 1972, with the other
Common Market countries understandably first on the list. To begin with,
Renault expect to concentrate on the 17TL as the standard British-market
car, at least until they can gauge possible demand for the other versions.
As a guide, prices in France run like this:
15TL, �1,190
15TS, �1,345
17TL, �1,500
2nd 17TS, �1,880.
This indicates that the 17TL will provide Renault in this country with a
new top end for their range at about �1,650.
A member of Autocity's road test staff recently visited France to drive
the new cars, and we hope to publish his impressions next week.
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