The suspension is identical with
that of the standard 16, the road holding being considered adequate to
cope with the additional power and not worth improving at the inevitable
expense of ride comfort. Double wishbones at the front are coupled to
longitudinal torsion bars with a flexible bush in the mounting of the
lower wishbone (the upper one is solid to maintain steering sensitivity)
to permit longitudinal compliance at the wheel which will absorb the
fore-and-aft resonance in the tread of the radial tyres, about which the
car was designed. The rear wheels are carried on trailing arms mounted
on transverse torsion bars and the compliance effect is obtained from a
flexible mounting for the bush outside each trailing arm. Because the
movement is very small in relation to the length of the torsion bar, the
chance of this inducing rear wheel steering is negligible. On the 16,
like his smaller brother the 4L, the two torsion bar casing lie one in
front of the other which accounts for the wheelbase on the offside being
2,75 in. shorter than the other but this is not noticeable in practice.
The suspension compliance is to cut out road roar and reduce the
magnitude of low speed thumps, to which radial tyres are particularly
susceptible, and the Renault bears out the theory in practice better
than most cars for which similar techniques are used.
The springs are very soft as they
must be to ensure a soft ride and the total travel very large. Anti-roll
bars at each end keep roll angles down to some extent but we felt they
could be strengthened without dire effects from excessive roll stiffness.
Roll is still the limiting factor on cornering speed as on dry roads the
adhesion, particularly with the new Michelins ZX tyres, is quite
remarkable; the discomfort of passengers or the protesting squeals from
the tyres are surer deterrents than the risk of breakaway. Often
prodigious under steer accompanies soft suspension but once set up the
Renault is virtually neutral because a mild initial understeer will
convert to a very slight and completely controllable oversteer at very
high speeds on long corners. This should not be confused with the
tuck-in which often occurs when lifting off with a fwd car because,
despite a sharper fall in power, the TS still shows almost negligible
response to sudden deceleration, Until we raised the tyre pressure a
little above recommended we found the tyre squeal rather embarrassing
even within the confines of city speed limits. The steering is also at
its worst under these conditions because in addition to being rather low
geared and a little on the heavy side, castor effects are greatly
influenced by the lock and power applied; accelerating hard out of tight
corners provokes quite savage self-centring and care must be exercised
not to let the steering wheel slip back through the hands too quickly.
Most of these traits disappear on the open road, the steering feels
lighter and pleasantly geared and the car can be hustled round corners
with considerable verve though it could be caught out by S-bends
lurching from side tot side with the roll transition.
The ZX tyres grip well in the wet
and their breakaway point is less precipitous than the previous
X-pattern. On light or trailing throttle, the Renault will corner inside
many saloons on a slippery surface but too sudden application of power
could break traction at the front end and then the car would run wide.
Occasionally, when a high roll angle was induced on a wet road, the
inside front wheel would lift or break traction and spin away the excess
power, an effect we found very difficult to provoke on a dry surface.
To help stop the car from higher
speeds, the front discs are 0,125 in. bigger in thickness and diameter
and fitted with a servo. This brings pedal load required for a 0,5g stop
down from nearly 50 lb. to 30 lb. although persistent locking of the
front brakes (effectively prevented at the rear by the pressure relief
valve) would not permit a maximum better than 0.9g. The brakes were
unaffected by our fade test and survived the after splash with a small
rise in pressure. The handbrake is a rather unsatisfactory affair
awkward to reach under the facia and would not hold the car on the 1 in
3 gradient though, on the test car, it was obviously out of adjustment.