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1977 Autocar Autotest

CitroŽn CX2400

Larger engine and slightly lower gearing make latest CX smoother and more responsive to drive.
Performance and fuel consumption little altered from former CX2200.
Superb comfort except for poor ventilation; exceptional steering, needs a lot of familiarization.
Good, relaxed cruising with restrained wind and mechanical noise levels.
An excellent car in all but a few respects

Return to CX Index page




DEVELOPMENT OF THE CitroŽn CX range has moved rapidly. Although it is still less than three years since the new model first appeared, there have already been three engine options added (including the diesel), while the Safari estate car has joined the range. The CX2200, which only last year we described as the "flagship of the CX range", has already been replaced.

Now the CX2400 is top model, but even this has been overtaken in France by introduction of the GTi, with fuel injection and a five-speed gearbox; this model is not yet available in the UK. Even when it comes there should be a strong position in the sales league for the 2400, which has effectively taken the place of the 2200 in the CitroŽn line-up, and that engine size is now offered only as a diesel.

Main difference between the two is the increase in bore diameter, from 90 to 93.5 mm. The capacity of the transversely-mounted four-cylinder engine goes up from the former 2,175 c.c. to 2,347 and compression ratio is reduced slightly, from 9.00-to-1 to 8.75. As before, there is a twin-choke Weber carburettor, only its size has changed. These differences are fairly small in percentage terms and the power increase is a mere 5 bhp, to the new DIN value of 115 at 5,750 rpm. Torque shows a bigger gain, going up from 123 lb.ft. to 135, and the peak comes lower in the rev range at 2,800 rpm instead of 3,500. These figures lead one to expect the main improvement to be noticed in better low-speed response rather than in any dramatic gain at the top end. So it is no surprise to find that the CX2400's performance through the gears is almost exactly the same for the CX220O Pallas which we tested in March last year. Acceleration from standstill to 60 mph took 11.8 sec against 11.6 for the 2.2-litre model, and 100 mph was reached in an equally close 40.1 sec instead of 40.8. Similarly, a standing quarter-mile time of 18.1 sec for the CX240O is almost identical with the 18.2 sec of the former car.

As the CX is not particularly high-geared, it is capable of being over-revved in top on a motorway descent - a point which the driver could well need to watch on a fast trip through Germany. On the level it readily reached 111 mph, with the rev counter beginning to move into the red zone at 6,100 rpm. The top speed is thus the same as that of the CX2200.

The extra torque available shows itself in improved response in the gears, rather than through them where power plays a greater part. Direct comparison with the 2200 shows useful gains in all gears in the respective 20 mph increments. It is this extra punch which is greatly appreciated on the road; it is not very tangible in terms of seconds saved in full throttle acceleration, but it makes the 2400 seem much more responsive. The difference is particularly marked in the better low-speed pulling in top gear and there seems less need for frequent gear changing.

All models are now slightly lower geared, having a final drive ratio of 4.77-to-1 instead of 4.58. This undoubtedly adds to the impression gained that the car is much more eager and flexible. It has the effect of lowering the maxima in the gears from 30, 52 and 85 mph to 29, 50 and 81 mph. Again, the changes are too small to quibble about, although a reduction in gearing is contrary to the current trend in the interests of economy.

We are sufficiently familiar with other CX models to be convinced that the 2400 engine is appreciably smoother than either of its smaller counterparts. To recall chief features of the design, the engine has five main bearings and the overhead valves are inclined, opening in hemispherical combustion chambers. For a four-cylinder unit the CitroŽn engine had an unusually large swept volume, but in this case big does not mean rough or harsh. It is very smooth right through the rev range and although there is a fair amount of throaty engine noise, it does not sound harsh or thrashy when revved hard.

Cruising at around 85 mph calls for only 4,400 rpm, which the CX sustains with a subdued and not obtrusive power roar. At the lower end of the rev range the engine pulls without snatch down to about 20 mph in top gear, although a change down to third becomes normal driving habit with the CX once the speed drops below about 30 mph.

Starting is always prompt, with use of the choke when cold; but the engine is surprisingly reluctant to fire when hot, calling for tedious churning on the starter motor. Warm-up is quick and the choke control can be pushed in halfway almost at once. It will pull without enrichment after about the first mile.


Well-packed and highly unorthodox, the engine bay houses not only the forward-inclined engine, with gearbox behind, but also the spare wheel. Despite the congestion, there is good access to sparking plugs, distributor and carburettor

Transmission

In first gear, the clutch takes up very smoothly from rest, but there is severe judder if any attempt is made to get away in second. A restart on the 1-in-3 test hill proved possible, but was achieved only with controlled clutch slip which produced a strong smell of burnt linings. Standing start acceleration tests were best done with abrupt clutch engagement at about 3,500 rpm, sufficient to produce front wheelspin for the first few yards, and crisp getaway. Too many revs lost time with excessive wheelspin. These techniques are in any case of rather academic interest for the average owner.

The gear change has sturdy, precise movement; it's very much a gear lever, rather than a gear stick. Synchromesh is effective on all gears but sometimes baulks for an instant. Care is needed to get the clutch fully down before engaging reverse to avoid a crunch of gears. Reverse gear position is parallel with third, and has strong check spring loading. The lever is also spring-loaded firmly to the third-fourth plane, and slips almost without need to guide it from second to third.

Fuel consumption

Since the gearing has been lowered and engine size increased, it is commendable that fuel consumption has not suffered. The CX240O returned 23.5 mpg overall - exactly the same as the figure for the CX220O Pallas. The body's excellent aerodynamic form obviously pays great dividends on a long, fast run while in contrast, London traffic running brings more than the usual penalty because of the considerable weight of the CitroŽn.

During the test we readily achieved 24-25 mpg from the CX24O0 saloon, while a recent opportunity for a long journey with the CX2400 Safari was even better, giving 25.9 mpg. Tank capacity of 15 gal means that 300 miles can be covered after filling up, still leaving a useful surplus of 30-50 miles before a refuelling halt.

After our 1,200-odd test miles a pint of oil was needed to restore the sump level. The dipstick is buried away at the back of the engine, and when the bonnet is open, care is needed to avoid rubbing clothing against the heavily-greased spring assister in the centre of the bonnet support strut.

An oil check button to the right of the facia gives a reading of oil level in a little glass tube; and to remind the driver to check it, a little light comes on in the indicator each time the ignition is turned on. It remains lit until the engine is started.

Steering and handling

Many people confess to feeling decidedly uneasy with the steering when they drive a CX for the first time, and there is no doubt that this highly sensitive. strongly assisted and powered self-centring system takes a bit of getting used to before one can feel at ease with it. On the straight it gives the impression of poor directional stability if the driver tries to correct the slight lateral movements of the car. It is almost a necessary discipline to learn that, if the steering is held steady, the car runs straight.

On corners, the power assistance still leaves need for a fair amount of effort to turn the wheel and the feel of the steering is very satisfactory - not over-assisted, yet not objectionably heavy. The assistance reduces progressively as speed increases and it makes very light work of parking or turning the car.

Unless the ignition key is taken out, locking the steering, the wheel automatically self-centres to line up the front wheels, even with the engine switched off, as soon as the wheel is released. Those who don't like the idea of the front wheels being turned in this way with the car at rest find themselves trying to avoid finishing up with the wheels on lock when parking the CX. Unladen, the front wheels carry twice the weight of the rear ones and inevitably there is strong understeer which the power assistance disguises to a great extent. In spite of this, there is little tendency for the front end to feel nose heavy and prone to slide straight on when cornering hard; indeed, the handling generally is excellent. The driver feels very confident of the response of the car and there is excellent grip on slippery roads. The only slight disappointment is the rather excessive degree of roll that occurs when cornering hard, but this is perhaps a safety factor, reminding the driver how hard he is pushing the car.


The clock, with second hand, is in the left of the four instrument squares. Fuel gauge and voltmeter are in the matching one on the right. The "travelling numbers" speedo and rev counter are plain to read, but only after the driver has taken his eyes from the road; they are illuminated automatically and brightness is adjustable by a thumb-wheel control beneath the right-hand control block. Finger-reach switches control horn, indicators (which are non-self-cancelling}, wipers and washers on the left; and lights, including dip and flash, on the right. The choke control to the right of the steering column has its own warning telltale just beneath and there is an illuminated oil-level check to the right below the eyeball ventilator. A formidable row of warning lights covers every function. Electric window switches are to either side of the gear lever

Brakes

Disc brakes are fitted all round, ventilated at the front, and the servo is powered by the central hydraulic system. Pedal load is unusually light, taking only 50 lb for maximum efficiency and response is always very reassuring, A pressure-limiting valve in the line to the rear brakes prevents them from locking up until the stage at which heavy braking on a slippery surface has caused the front ones to lock first. Generally, the adhesion under braking is very good and the car is not prone to slide on with locked wheels.

Fade testing produced a slight initial increase in pedal load, but by the fifth application from 70 mph, the effort had stabilized. The handbrake works on separate pads on the front discs, and really can serve as an emergency brake, capable of 45 per cent efficiency. It holds securely, and without need for specially hard application, on the 1-in-3 test hill. As well as the central warning tell-tale marked "STOP", to warn of loss of hydraulic pressure, there is an amber warning lamp for front pad wear.

Ride and comfort

All the elaboration of self-levelling, hydro-pneumatic suspension on the CX is justified by the magnificent ride which results. The car absorbs undulations, humps and bumps superbly well and the resultant very resilient ride is also firmly damped. There is no swaying or wallowing and hump-back bridges taken quickly do not catch the suspension out. The only weak point of the system is the slight delay taken to recover normal ground clearance after the car has stood for a while.

Initial movement of the suspension is very firm, evidently with little rubber in the mountings and, as a result, a lot of harshness is transmitted on certain surfaces and there is a sharp report if a wheel hits a road cat's eye.

The ability to increase the ground clearance by means of the control lever beside the driving seat was useful on more than one occasion, and enabled us to negotiate flood water that would otherwise have been impassable.

As well as a high standard of ride comfort, the CX has well-shaped, softly upholstered and extremely comfortable seats. A lever to the right of the driving seat, centrally pivoted, allows the tilt of the cushion to be altered, having the effect of providing vertical height adjustment. Another lever farther back gives rake adjustment for the backrest (similarly for the passenger seat) and a very comfortable driving position can be achieved.

Headrests are standard, with detachable cushions; the headrests themselves can be removed, but this has to be done with care otherwise the splayed nylon feet tend to tear the top of the support tubes away from the seat.

Although so much of the car has been well designed, the ventilation remains one of the chief weak points. Through-flow is poor and delivery from the eye-ball vents is dependent on having the decidedly noisy blower in use. In hot weather, the air coming\through the ventilators tends to get warmed above ambient on its way through the system, making the car very hot inside. In contrast the heater is slow to warm up and is of the water-valve type, giving little if any progression between full on and full off.

Controls and equipment

For simplicity and convenience, the layout of minor controls in the CX is one of the best there is. Switches for wipers, indicators and horn are within finger reach when holding the wheel normally with the left hand; and matching controls for the right hand operate the three lighting switches - off, side, head below the finger block, flasher switch on the side, and dip switch on the top. First pressure on the horn switch sounds a gentle "beep" suitable for town, and a firmer press fires up very effective air horns mounted under the bonnet.

Electrically-operated front windows are standard, their switches being to either side of the gear lever, on the lower part of the central console. Adjacent, farther back, are switches for the interior light, which is adequately bright for map reading, and for the heated rear window. There is a lockable, drop-down compartment to the left of the facia and an open cubbyhole on the right.

Instruments are digital, with variable light intensity controlled by a thumb-wheel beneath the right-hand control block. The markings are clear and the speedometer and rev counter proved accurate, but there is no denying that the driver has to take his eyes from the road to be able to read them clearly; they cannot be seen out of the corner of the eye, as can the normal analogue type.

Minor instruments are confined to a vertically-reading fuel gauge and voltmeter, with clock having sweep second hand on the left. Across the top of the instruments is a row of warning lights, all individually labelled with symbols. The important central ones, for hydraulic pressure, brake line pressure, oil pressure and water temperature, can all be tested by a touch on a button in the right-hand lamp of this central group.

The front doors cannot from outside before closing, but the locking catches are at the leading edge of each door and it is easy for the driver to lock the three passenger doors before getting out. There are child safety catches for the rear doors. The boot has an interior light, operated by raising the lid and the boot lid can be left unlocked when required.

The CitroŽn's huge windscreen is well swept by the single, centre-pivoted wiper, though we have noticed before that the CitroŽn CX windscreen tends to get very smeary, perhaps as a result of the unobstructed wind flow over the front of the car.

An irritating detail is that the rather crude door-mounted mirror tends to blow back in the wind at speed, despite efforts to tighten it; and the interior mirror, which is bonded to the windscreen, fell off and defied all attempts to stick it back on. The seat belt inertia reels tended to be very sensitive and reluctant to unlock on the test car, so it was important to fasten belts before driving off.


Above: as well as the usual adjustment to-and-fro for the seat and its backrest angle, there is vertical adjustment to tilt the front of the seat cushion
Left: the headrests have detachable cushions and they can also be removed altogether for better visibility or out of consideration for rear-seat passengers
Below: The appearance of the facia is neat, but the vertical mounting for the radio/tape unit is totally unsatisfactory, making it dangerously difficult for the driver to see its tuning scale


Above: rear-seat comfort is as sumptuous as in front, and there is a folding centre armrest. Air from the heater is channeled through to the rear compartment

Below: removal of tools and spare wheel to the engine compartment leaves the boot pleasantly clear, with a low floor. A boot light is standard


Specifications

ENGINE

Cylinders
4 in-line
Main bearings
5
Cooling
Water
Fan
Electric
Bore, mm
93.5
Stroke, mm
85.5
Capacity c.c.
2,347
Valve gear
ohv
Camshaft drive
Chain
Compression ratio
8.75 to 1
Octane rating (minimum)
97 RM
Carburettor (make & type)
Weber twin choke 34 DMTR 35/250
Max power
115 bhp (DIN) at 5,500 rpm
Max torque
131 ft. lb. at 3,000 rpm
TRANSMISSION
Clutch
Single disc dry type
Gear ratio:
Top
0.8
3rd
1.133
2nd
1.833
1st
3.153
Final drive gear
Helical spur
Ratio
4.77 to 1 13/62
SUSPENSION
Front -location
Independent, double wishbone
- springs dampers
Hydropneumatic units
- anti-roll bar
Yes
Rear -location Independent, trailing arms
- springs dampers Hydropneumatic units
- anti-roll bar Yes
STEERING
Type
Rack and pinion with power self centring
Power assistance
VariPower standard
BRAKES
Front
10.23 in. dia. ventilated discs
Rear
9.7 in. dia. discs
Servo
Yes. Hydraulic
WHEELS
Type
Pressed steel disc
Rim width
5 1/2in. J
Tyres - make
Michelin
- type
Radial tubeless XVS
- size
Front 185-14
Rear 175-14
EQUIPMENT
Battery
12 volt 55 Ah
Alternator
72 amp
Headlamps (dipped/full beam/ wattage 4-lamp halogen. 90/190 watt (total)
Reversing lamp
Standard
Hazard warning
Standard
Electric fuses
2 fuse boxes, 10 fuses
Screen wipers
Two-speed
Screen washer
Electric
Interior heater
Water valve
Interior trim
Cloth seats, vinyl headlining
Floor covering
Carpet
Jack
Screw type
Jacking points
4, below front and rear doors
Windscreen
Laminated
Underbody protection
Paint system and wax
MAINTENANCE
Fuel tank
15 Imp galls (68 litres)
Cooling system
18.5 pints (inc heater)
Engine sump
8 pints SAE 20W50
Gearbox and final drive
3 pints SAE 80
Grease
No points
Valve clearance (cold)
Inlet - 0.006 in.
Exhaust - 0.008 in.
Contact breaker
0.016 in. gap 55 deg dwell angle
Ignition timing
10 deg BTDC (static or 00 deg stroboscopic at 850 rpm)
Spark-plug - type
AL42 FS
- gap
0.028 in.
Tyre pressure
F 28; R 30 psi (normal driving)
Max. payload
1,080 lb (490 kg)

Test Scorecard

(Average of scoring by Autocar Road Test Team)
Ratings

6
Excellent
5
Good
4
Above Average
3
Below Average
2
Poor
1
Bad
PERFORMANCE
4.17
STEERING AND HANDLING
5.08
BRAKES
5.00
COMFORT IN FRONT
3.92
COMFORT IN BACK
4.86
DRIVERS AIDS
(instruments, lights, wipers, visibility, etc)
4.88
CONTROLS
4.63
NOISE
4.17
STOWAGE
4.00
ROUTINE SERVICING
(under bonnet access, dipstick, etc)
4.00
EASE OF DRIVING
4.64
OVERALL RATING
4.53

Maximum Speeds

Gear
mph
kph
rpm
Top (mean)
113
182
5,870
Top (best)
116
187
6,025
3rd
81
130
6,000
2nd
50
80
6,000
1st
29
47
6,000

Acceleration

True mph
Time (sec)
Speedo mph
30
3.6
30
40
5.8
41
50
8.1
51
60
11.8
61
70
15.7
71
80
21.0
82
90
28.9
92
100
40.1
103

Standing 1/4 mile
18.1 sec
78 mph
Standing kilometre 33.5 sec
92 mph
mph
Top
3rd
2nd
10-30
-
6.9
4.0
20-40
9.9
6.2
4.0
30-50
9.2
6.0
4.4
40-60
9.4
6.4
-
50-70
10.6
7.4
-
60-80
11.7
9.3
-
70-90
14.1
-
-
80-100
19.2
-

Consumption

Fuel
Overall mpg
23.5 (12.0 litres/100 km)
Calculated (DIN) mpg
23.7 (11.9 litres/100 km)
Constant speed
mph
mpg
30
39.9
40
37.1
50
32.5
60
28.6
70
26.0
80
22.5
90
19.7
100
16.4
Autocar formula
Hard driving, difficult conditions
21.1 mpg
Average driving, average conditions
25.9 mpg
Gentle driving, easy conditions
30.6 mpg
Grade of fuel
Premium, four star (98 RM)
Mileage recorder
1 per cent over reading
Oil
Consumption (SAE 20W/50) negligible

Brakes

Fade (from 70 mph in neutral)
Pedal load for 0.5g stops (lb)

start/end

start/end
1
25
6
40/50
2
30/35
7
40/55
3
35/40
8
40/55
4
35/40
9
40/55
5
40/50
10
40/55
Response (from 30 mph in neutral)
Load
g
Distance (ft)
20
0.35
86
30
0.55
55
40
0.72
42
50
0.95
32
Handbrake
0.45
67
Max. gradient
1 in 3

Clutch

Pedal 40 lb and 5 1/2 in.

Test Conditions

Wind: 0.5 mph
Temperature: 17 deg C (63 deg F)
Barometer: 30.2 in. Hg
Surface: dry asphalt and concrete
Test distance: 1,200 miles
Figures taken at 10,000 miles by our own staff at the Motor Industry proving ground at Nuneaton

Regular Service

Interval (miles)
Change
3,000
6,000
12,000
Engine
Yes
Yes Yes
Oil filter
No
No
Yes
Gearbox
Check
Check
Yes
Spark plugs
Clean
Check Check
Air filter
No
Clean Clean
C/breaker
No
Check Check
Total cost
£2.80
£10.64
£27.72
Assuming labour at £5.60 / hour

Weight

Kerb 26.7 cwt / 2,990 lb / 1,357 kg
Distribution F/R 67.4/32.6
As tested 30.2 cwt/3930 lb/1,540 kg
Boot capacity 16.8 cu. ft.
Turning circles
Between kerbs L, 35 ft 9 in R, 35 ft 4 in
Between walls L, 38 ft 8 in R, 38 ft 6 in
Turns lock to lock 2.5

Parts Cost

(including VAT)
Brake pads (2 wheels) - front
£16.90
Brake pads (2 wheels) - rear £11.54
Exhaust system, complete
£75.41
Windscreen (laminated)
£88.65
Headlamp unit
£42.98
Front wing
£38.17
Rear bumper
£104.03
Warranty period
12 months/12,000 miles

Comparisons

Car
Price (£)
Max mph
0-60 (sec)
Overall mpg
Capacity (c.c.)
Power (bhp)
Wheelbase (in.)
Length (in.)
Width (in.)
Kerb weight (cwt)
Fuel (gal)
Tyres size
CitroŽn CX2400 4,991
113
11.8
23.5
2,347
115
112
181
68.0
26.7
15.0
185/175 HR 14
Audi 100 GLS
5,286
107
10.9
21.4
1,984
115
105.5
184
69.5
22.6
13.2
165-14
BMW 520
5,729
114
10.5
22.4
1,990
130
104.0
182
67.0
24.6
12.5
175HR-14
Ford Granada 3000GL
5,147
113
9.4
17.4
2,664*
138
109.0
180
71.0
27.8
14.3
175HR-14
Renault 30TS
5,458
111
11.7
20.2
2,664
131
105.0
178
68.0
25.5
14.7
175HR-14
Rover 3500
5,983
123
8.4
20.5
3,528
155
110.5
185
69.0
27.2
14.5
185-14
* I think this is an error - according to Wikipedia, the capacity was 2,994 cc.


© 2015 CitroŽnŽt/1977 Autocar