1951
- March: The AU is introduced. Differences with the A are 7×31 crownwheel pignon (normally 8×31), speedo gear with 18 teeth, 10mm plate between chassis and rear axle mountings, fueltank fitted to the right side of the body, 135×400 tyres, spare wheel is fitted to the left of the body. On the rear, the panels next to the doors are flat without reinforcements. Topspeed 60 km/h.
- October: Suspension; No rubber protector on the bottom of the rear batteur any more.
- November: Bonnet; The edge of the grill now has visible screws.
1952
The panels next to the rear doors on the AU are no longer flat.
- February: Gearbox; gets a 28mm input shaft.
- March: Speedo; is replaced by one made by E.D.
- April: Accellerator; the accellerator rod gets ball pivots.
- May : Gearbox; the clutch pressure plate now has 3 springs instead of 6.
- June: Brakes; backplates are steel instead of aluminium, the front brake drums get 4 ridges instead of 3, new handbrake cables.
- September: Engine; the cupper seal between the head and the barrel is left out.
Suspension; the front axle tube is now 65.5mm diameter instead of 64.5mm due to an increased diameter steering rack. - October: A grey steeringwheel and scottish plaid, plastic covered upholstery.
- November: Electric; dynamo is now fixed with 2 bolts instead of 3, this also means engine mods.
1953
- March: Bonnet; the oval around the chevrons on the bonnet dissapears.
- May: Bonnet; the welding seams on sides of the bonnet change, top to bottom becomes front to rear.
Bonnet; is now opened with a turning handle instead of the pull handle.
Suspension; arms front and rear get 25.5mm bearings instead of 28.5mm. - June: Engine; now has a 4 blade fan, different airfilter and strengthened crankshaft.
Doors; door edges are turned instead of welded. The opening mechanism on the front sidescreens is modified.
The bonnet gets a central rod support instead of the tubular frame. - July : Steering; the steering tube is modified.
1954
- January: Electric; the Paris Rhone dynamo is improved.
- March: The PO version is available. This has modified chassis, suspension, airfilter and other things to make it suitable for rough terrain and the overseas territories.
- April: Electric; the voltage regulator is moved from the left to the right of the firewall.
Fueltank; the fuel filler pipe is reduced in diameter from 55 to 45mm, so is the hole in the rear wing.
Doors; the doors get a rubber to keep the windows in the upright position. - June: Headlights; the clip on the Cibie headlights is no longer screw on.
- July: Electric; the rectangular metal coil is replaced by a round one, completely covered in rubber, headlight support modified for this.
- September: New model, the AZU. 425cc engine, 12hp, 6 blade fan, 6.2:1 compression, 70 km/h, 8×31 crownwheel pignon. Electric; AZ rear lighting now has 2 rear lights with 1 integrated brake light. Also indicators on the C post doubling as position lights. For this a plate is fitted to the dash with the indicator switch and parking light switch.
Electric; the battery is no longer secured with a U profile but with a V one with two pullrods spring loaded. Gearbox; gets an 8 tooth primary shaft.
Dashboard; the handbrake lever is increased in diameter from 12mm to 13mm. - October: Headlights; apart from the Cibie also Marchal Equilux headlights are fitted, identifiable by the steel edge on the lense.
- December: Dashboard; the starter cable is modified.
Suspension; The AZU gets visible springs. For this the chassis is adapted.
1955
The AU is no longer in the pricelist and is only rarely sold any more.
- January: Electric; Indicators sides of the luggae compartment and the AU gets the same lights and electrical equipment as the AZU.
- April: Electric; the wiring gets 4mm connectors instead of 2.5mm ones.
Production is transfered to the Panhard factory at l’avenue d’Ivry, Paris.
Dashboard; the speedo gets a light. - May: Suspension; the AZU gets the normal suspension again.
- June: Suspension; the springs on either end of the spring retainer tube are replaced by rubber doughnuts, 2 on the front and 1 on the rear of the pot. September: Electric; the Dynamo is modified.
Headlights; there is an alu edge on the lense/reflector on the Cibie headlights. - November: Engine; compression on the AZU is raised from 6.2 to 7:1 by using domed pistons. Also new carburettor.
- December: Gearbox; the clutch plate and primary shaft now have 10 teeth instead of 8.
Dashboard; gearlever ball is now gray instead of black.
Interior; seat frames are dark gray.
1956
- January: Electric; a second horn is fitted.
- May: Body; there is a hole on either side of the windscreen to let out water.
- April; Doors; seal fitted to the top of the opening front window.
- July: Dashboard; apart form the Jaeger and E.D. speedos an O.S. one is now also availbale.
- September: Electric; the Paris Rhone starter is modified.
- December: The wheels, bumpers, steeringwheel, seat frames and gearlever ball are all light gray.
Body; rear roof is one piece instead of 3 piece so no welding seams front to back, opening for the indicators in the ripples and a potruding edge on the front of the roof with aditional profiling on the front of the luggage compartment.
Doors; Flexarmit door covers.
1957
- January: Electric; the rear lights are changed again.
- May: Brakes; all 2cvs get a glass lockheed brake fluid resevoir.
- August: Engine; Some engines get forged ribs on the cylinders.
- October: Bonnet; a rubber is fixed to the bottom of the bonnet.
1958
Suspension; the spring retainers are lighter and have a smaller diameter.
- January: Gearbox; the rear mount is changed and will remain like this to the end.
- February: Brakes; the front brakedrums lose 2 ridges and are now completely smooth.
- July: Suspension; front batteur modified, now left and right are different.
- September: Engine; all engines get forged ribs on the cylinders.
- November: Interior; the sun visor is fixed with 2 screws instead of 4.
1959
- May: Dashboard; new heating system with small windscreen demister on the left of the dashboard.
Gearbox; some cars fitted with constant velocity driveshafts. - July: Suspension; only one rubber doughnut on the front of the spring tube instead of 2.
Interior: cardboard sun visor replaced by plastic one. - September: Suspension; new fully closed 125×380 wheels and tyres. Kingpins are also modified.
1960
- January: Electric; new horn fitted.
- June: Electric; New starter.
Doors; new doorlocks with 4 digits on the key instead of 3. - July: Interior; the seats are now secured to the chassis at the back as well.
- September: Interior; top of the seat frame and dashboard edge covered, metal knob with rubber cover for shutter, everything that is not the body colour is light gray.
- November: Electric; hard plastic coil replaces rubber covered one.
Body; windsreen rubber is curved instead of hollow.
Engine; the AU 375cc version is discontinued. - November: Gearbox; constant velocity driveshafts discontinued.
- December: Bumper; new bumper shared with the berline.
Dashboard; new position light switch with plastic handle instead of steel one.
1961
Additional profiling next to the rear license plate.
Through Citroën several side windows made by Glaçauto are available.
- April; Engine; oilcooler is modified.
- July 10th: Body; new 5 ripple bonnet with detachable grille.
- October: Engine; the compression is raised to 7.5:1 giving 13.5 hp. Topspeed is now 85km/h.
Dashboard; speedo runs up to 100km/h instead of 90. - November: Dashboard; the ampere meter is replaced by a red warning light.
Electric; the connections for the headlights are now on the left side of the headlight bar.
1962
- February: Brakes; a new master cylinder is fitted, similar to the Ami 6 one, brake hoses are also changed.
Bonnet; the grille now has countersunk screws 371mm apart instead of 426mm. - April: Engine; the carburetor is upgraded and more heater ducts enclosing the sparkplug.
- May: Dashboard; Radioën option is discontinued.
- July: Electric; improved dynamo and starter, one horn with double function.
- September: Dashboard; integrated dashbord with fuel gauge, speedo and total distance counter fitted behind the steering wheel. Dashboard; windscreen wipers are now electric. Heating is modified. Steering tube is larger diameter.
Green cloth for interior.
1963
- January: Oilpump and the gearbox is modified with 8×31 crownwheel pignon.
- February: Engine; 18hp, identified by 4 manifold bolts on each side instead of 3, 95 km/h topspeed.
Ami 6 wheels, the brake linings are glued instead of rivited, plastic door covers stapled to cardboard, new bigger bumpers. - March: Body; bigger square windows in the rear doors, the sides of the rear body get a flat piece with a window in them.
Doors; rear view mirror moved from wing to door.
Headlights; Chrome trim on the Cibie and Marchal units. - April: Electric; red plastic indicators replacing steel covered ones.
- May: The AK appears. This is a 20cm longer version of the AZU with the Ami 6 602cc engine, 350kg load capacity.
- June: AK available with glacauto “week-end” or “break” fittings.
- September: Suspension; the AK gets for telescopic shockabsorbers.
- October: Dashboard; the indicators are now operated by a lever on the steering tube.
1964
- January: Body; dents in the roof over the driver and passenger on all types.
Interior; seatbelts are optional. For this the chassis and body have been modified. - March: Electric; rear lights with integrated licenseplate light???.
- April: A round plate with the colour number placed on the firewall.
- June: Wheels; tubeless tires and modified rims.
- July: Brakes; reduced diameter line from 6mm to 4.5mm.
- November: New gearbox ratios for the AZU.
- December: Doors; front doors are no longer suicide but open at the rear.
1965
- January: Suspension; the AK gets shockabsorbers all round.
- May: Interior; round interior light is replaced by a rectangular one with switch.
- Mai: Steering; on the AK the steering rods are secured by nyloc nut and no longer with split pins.
- June: Steering; the steering rods are secured by nyloc nut and no longer with split pins.
- July: Lights; Parking light through rear light and no longer through indicator.
- September: Body; optional opening panel above the rear doors, licenseplate fitted below the bumper.
Grille; one piece grille is replaced by 3 horizontal bar grille, chevrons mounted on the bonnet.
Bumper; new bumpers with black nylon in the center.
Suspension; on the AZU the frotteurs at the rear are replaced by telescopic shockabsorbers. At the front the frotteurs are protected by extra rubber.
Gearbox; optional constant velocity driveshafts.
1966
- February: Electric; 12V instalation with alternator on the AK.
- March: Suspension; constant velocity driveshafts on the AK.
- May: Dashboard; steering lock is optional.
Gearbox; fine splines on the primary shaft of the AZU.
April: Option; heater running on fuel from the fuel tank, it has a inlet on the front wing and runs on 12V electrics. - September: The handbrake now has a plastic handle.
Doors: new securing clips for keeping the front side windows open.
Engine: the AK gets sound deadening on the engine shrouding.
Handbrake: the AK gets a new handbrake lever. - December: Engine; the valvecovers are now secured with a conical base nut.
1967
- May: Bonnet; the bonnet securing mechanism is simplified to one piece operated underneath the bumper.
- August: The AZU gets an uprated 21hp 425cc engine.
- October: The AK350 gets a fully new gearbox, modern type.
1968
- March: Gearbox; AZU gets new gearbox ratios.
- May: The AK350 gets an uprated 33hp engine, hanging pedals and a modified heating system.
- September: Brakes; the return springs on the rear brake shoes are replaced by U shaped rods.
- October: Electric; twin rear brake lights, orange indicators replacing red ones.
Engine; ignition box is modified.
1969
- March: Engine; alloy valve covers are replaced by steel ones.
- April: Brakes; rear flexibel brake hoses replaced by spirale shaped lines 3.5mm inside the rear axle on the AK.
- July: Supension: AZU, the plates under the rear axle are removed, the spring cylinders are changed and the height of the chassis is readjusted.
- September: Dashboard; steering lock and windscreen washer.
Headlights; Marchal and Ducellier headlights are discontinued.
1970
- February: 12V electrics, hanging pedals, modified heating, Ami 6 rear lights on a modified rear body panel, front square indicators on the wings, front side windows in stainless steel, new black plastic 2 spoke steeringwheel and big dashboard.
- April: Interior; 2 point seatbelts standard.
- June: Brakes; the diameter of all brakelines is changed 3.5mm on the AZU.
Lights; the front square indicators are replaced by round ones.
Brakes; The rear flexible brakehoses are replaced by spring shaped brakelines in the rear axle. - July: AK is replaced by AKS, wide ripples on rear wings, covers and rear doors, 12cm raised roof, big berline dashboard, plastic berline steering wheel, interior light, no side indicators.
- September: Engine; the AKS engine gets a 9 blade ventilator.
- October: Body; the rounded rubber profile on the bumpers is replaced by a gray one with different shape.
- November: Engine; the AKS engine gets an external oil filter.
Suspension; telescopic shockabsorber replace rear frotteurs and batteurs on the AZU. - December: Interior; black plastic rear view mirror.
1971
- September: Interior; the diameter of the brake and clutch pedal pivot is enlarged.
Dashboard; AZU gets plastic steering wheel to replace steel one.
Suspension; telescopic shockabsorber replace rear frotteurs and batteurs on the AKS. - October: Suspension; some AZU get special Rzeppa driveshafts.
1972
- January: Body; AZU gets wide ripples, no side indicators, hanging pedals, officially called 250.
AZU serie A with 425cc engine 6V, serie A for big corperations only.
AZU serie B with 435cc engine 12V. - August: Engine; new carburettors for all cars.
- September: Interior; strengthened hinges.
Suspension; eyes on spring pull rods are no longer round but now hexagonal.
AZU serie A is discontinued. - October: Engine; hardened bolt for fixing ventilator.
1973
- July: Brakes; bigger master brakecylinder.
Lights; position lights discontinued, along with 3 position switch on dashboard.
Dashboard; ashtray fitted into plastic cover for wiper motor and ventilation deflector.
Dashboard; brown plastics replacing gray-blue.
Dashboard; 250 gets big speedo.
Electric; voltage regulator fitted to the battery.
Electric; AKS get start button to replace pull starter.
1974
- January: Body; no side windows.
- March: Engine; hardened toothed belt on the flywheel.
- September: Body; square headlights, plastic grille with chrome edge and chevrons inside, bigger rear bumper, black rubber protector replaces gray one.
Dashboard; starting button replaced by starting with the ignition key, choke moved from left to right.
1975
- January: Engine; the airfilter gets a black plastic cover.
- March: Engine; AKS exhaust modified to reduce noise levels.
- September: Suspension; front telescopic shockabsorbers replace batteurs and frotteurs.
Body; the rubbers on the bumpers are replaced by black tape.
Steering; new steering ratio and a smaller 2 spoke hard plastic steering wheel.
Dashboard; Steering lock standard.
1976
- March: Engine; new crankshaft seals.
- August: All plastic interior parts are black again. The speedo backplate remains brown.
- September: Brakes; dual feed brake resevoir, brake fluid level sensor, warning light and light test button.
Suspension; fixed Ami suspension tubes on the AKS. - October: Body; The type plate on the bootlid is now a plastic sticker.
1977
- February: Body; side windows again.
- July: Interior; 3 point fixed safety belts, piramids on the inner wings.
1978
- March: 250 and AKS replaced by Acadiane.
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