Citroën A-type P.O.

© Copyright: J.Cats.


Disclaimer:
This page only provides information based on the personal opinion of the author. The author can't be held responsible for damage in any way that could result from modifications mentioned here.

P.O. stands for Pays d'Outre-mer (overseas countries). It's the Citroën name for cars with special preperation, making them more suitable for difficult terrain. Citroën A-types have a long P.O. history, the first P.O. 2CVs being built March 1954. All Mehari have some P.O. preperation, especially the 4x4. The most famous P.O. of all is the 2cv Sahara. This is a twin engined 4 wheel drive 2cv, quite rare nowadays. In the 70s Citroën organised some rally raids for 2CVs and derivatives. These were long journeys through desserts and other normally not encountered terrain. To prepare the participants for these raids, Citroën published the famous book Ici commence l'aventure.

With the information from these sources, including looking at original P.O. cars such as the Sahara, Mehari and P.O. 2CVs, i've compiled this page. This page can help you to built a 2cv well suited for the most difficult terrain and journeys. This is not a step by step guide. It can give you some ideas and solutions but you'll still have to do some development work yourself.


Chassis
For the chassis there are 2 options. Either start of with a replacement chassis that is made up from tubes (such as the Wheels chassis) or get a good original type one. Original Mehari and Acadiane chassis always have some P.O, strenghtening.

When the original type one is used, the following reinforcements can be made:

Chassis reinforcement

  • 1: Reinforcement of the front chassis beam in front of the front axle. Reinforcement C in the picture. This is for reinforcing the front engine carrying construction.
  • 2: Reinforcement of the chassis beam between the front axle and front spring tube carrier. Reinforcement A in the picture. This is for reinforcing the suspension carrying structure.
  • 3: Reinforcement of the chassis beam between the rear spring tube carrier and the rear axle. Reinforcement D in the picture. This is for reinforcing the suspension carrying structure.
  • 4: Reinforcement of the front axle bolt retainers. This is reinforcement B in the picture. This is for reinforcing the front suspension structure.

Axles
Acadiane or Mehari axles are prefered. These have a reinforcement welded over the gearbox mount. When these are not available 2cv axles can be used and the gearbox carrier reinforced as in the picture.
All axles can be reinforced with the U profile as shown in the picture below.

Axle reinforcement

Suspension arms
All arms can be additionally reinforced by cutting them open along the welding seam and welding a 2mm plate between the 2 halves of the suspension arms. All bump stops on the suspension arms can be reinforced as in the picture.

Bump stop reinforcement

Wheels
Fit 145x15 (GSA) or 155x15 tyres on 2cv or GSA rims. Tyre pressure of 1 bar / 14 psi gives a very large footprint and very low pressure per square mm. This is very important for off road driving.

Fuel tank
A big 60-80 liter fueltank (DS, CX) can be fitted to replace the small A-type fueltank (or as a additional tank!). It can be fitted in place of the rear bench and greatly increases the range. At all times a steel 20 liter "jerrycan" should be taken along on long voyages.

Body
The body can be strengthened in the following places:

  • Front bulkhead
    The front bulkhead needs reinforcements to cope with higher speed driving over rough terrain. A tubular subframe is welded to the inside, replacing the conventional dashboard.
  • Floors
    The floors are strengthened by making them out of 1.2mm sheet with 1.2mm crossmembers underneath. The crossmembers running front to rear are extended to cover the whole body.
  • Roof
    The small tubes spanning the roof are replaced by a 40x20x2mm tube secured to the body by triangulation.
Alternatively or additionally a roll cage can be bolted or welded into the body for additional strengthening.

Headlights
The headlights are protected by fine wire mesh grilles.

Front wings
All front wing mounting points are replaced by enlarged 1.2mm ones, plug welded into place. The front of the wings can be cut away to keep away sand builting up in the wings.

Bonnet
Besides or replacing the normal bonnet securing mechanism are 2 rally style securing clips (stainless steel, not rubber!) to keep to keep the bonnet closed in all conditions.

Rear wings
The rear wings are cut away as can be seen in the picture below. The picture shows a 2cv wing, but the same method can used on the Dyane and Ami rear wings. This keeps sand from builting up in the wings. Make sure the wings clear the (bigger) wheels under ALL circumstances (full suspension travel).

Rear wing

Bumpers
The front bumper is a tubular one with attached sump guard covering the whole engine bay, leaving both engine and gearbox protected. It's adviceably to put some additional lights on the front bumper, protecting them with fine wire mesh.

The rear bumper is a also tubular one. The fuel tank has to be protected. Either attach a sump guard covering the fueltank to the rear bumper or fit a seperate plate to cover the fueltank.

Make sure strong towing hooks/eyes are attached to the bumpers.

Front bumper

Front sumpguard


2x2

With the modifications described above, Citroën A-types are excellent raid vehicles. But for real off road driving it can be improved upon. This by fitting twin engines giving 4wd. Here are some tips on how to make the modifications needed.

Chassis
Besides the reinforcements mentioned earlier some additional reinforcements can now be made.

  • 5: Reinforcement of the rear chassis beam behind the rear axle. This reinforcement is not shown in the picture but similar to reinforcement C. This is for reinforcing the rear engine carrying construction.
  • 6: Rear suspension arm travel limiter (bump stop). Aditional travel limiters on the rear axle are needed. These are the same as the front ones, welded to the side of the chassis.
  • 7: Reinforcement of the rear axle bolt retainers. This reinforcement is not shown in the picture but similar to reinforcement B. This is for reinforcing the rear suspension structure and fits over the new rear bump stop.
Springs
At the rear a higher spring ratio is needed. 2cv6 or Dyane spring tubes are opened by cutting away a weld on one of the ends and the rear springs are replaced with a second pair of front ones. The rear spring connecting rods are replaced by a pair of front ones as well.

Axles
Twin front axles are used. 2cv van, Acadiane, Mehari or Ami axles are prefered. These have a reinforcement welded over the gearbox mount. When these are not available other 2cv axles can be used but the gearbox carrier should be reinforced as in the picture.
All axles need the reinforcement U profile as shown in the picture below.

At the rear the steering is locked off. For this the steering rods are replaced by rosejoints and these are secured to the suspension arm. The tracking adjustment is retained. All steering equipment is removed from the rear axle tube.

Shockabsorbers
Fit 2cv6 or Dyane front shockabsorbers on both the front and the rear.

Gearchange
The gearchange is a floor mounted gear change mechanism. It is modified in such a way that it can operate either or both the front and rear gearbox.

The easiest solution is to use 2 levers, one for each gearbox, but this makes quick gearchanges a bit difficult (Aryan Schmitz).

The original sahara worked by not operating the levers on top of the gearbox lid but operating the sliding shafts inside the gearbox lid on which the selector forks are fixed. This makes operating the 2 gearboxes slightly easier then using the normal operating levers.

Clutches
The clutches are hydraulically operated. This system uses 1 master cylinder fitted on the bulkhead next to the brake master cylinder and 2 slave cylinders fitted inside the bellhousings of the 2 gearboxes.

Engines and gearboxes
Make sure both engine and gearboxes are of the same type. The prefered engines are Dyane AM 2 engines for their extra power. The prefered gearboxes are 2cv6 discbrake gearboxes, for their slightly low gear ratios and the performance of the disc brakes. Mount the rear drivetrain on the gearbox / axle mount and mark out the position for the engine support crossmember. Use a similar crossmember to the original front one and fit it in the same way.

Front engine:
The carburettor of the front engine has to be modified. The throttle of the rear engine is controlled by the front throttle through a cable. Exhaust for the front engine is a normal 2cv exhaust but with AK end pipe exiting in front of the left rear wheel.

Rear engine:
The carburettor of the rear engine is controlled by the front one through a cable. Exhaust for the rear engine starts off with the normal silencer under the gearbox. The exit pipe from this silencer is cut off and modified in such a way that the exhaust exits behind the right rear wheel.

Front gearbox:
No modifications needed.

Rear gearbox:
Swap over the differential so that the crownwheel is on the other side of the gearbox. This compensates for the gearbox being positioned back to front.

Rear bulkhead
The rear of the body is strengthened by welding an additional firewall onto the inner wings, just rear of the C post. This firewall is made up from 1-1.2mm sheet steel. The rear floor is completely cut away and replaced by a floor that runs up to the chassis members and bolts onto these members. Between the chassis members is big hole for the engine and gearbox. Additional box sections are welded to the bottom of the inner wings connecting them to the floors.

Body rear end
The section holding the rear lights is cut out, providing a bigger boot opening. At the bottom of this opening sits a 30x30x2mm square tube, connected to the body with triangulation and bolted to the chassis. The small tube above the bootlid is replaced by a 30x30x2mm square tube which is also connected to the body by additional triangulation.
Through extra intakes, additional cold air is fed to the engine. The bump stops on the inner wings are removed.

Fuel tank
With twin engines there is no place for the original tank so the larger fueltank option is used. It feeds both engines through twin pickup points inside the tank.

Boot lid
The bootlid is extended downwards over the license plate panel. It has a round opening for the engine cooling intake. Rear lights are fitted on separate panels in the bottom corners of the bootlid, fixed to the body. They are protected by fine wire mesh grilles. Two brackets are made to keep the bootlid open a few cm when heat built-up in the rear engine becomes a problem. The bootlid securing mechanism is by 2 rally style securing clips (stainless steel, not rubber!) to keep it closed in all conditions.

Sumpguard
For the rear engine and gearbox a sumpguard is needed, similar to the front one.

Electrical system
To obtain the maximum reliability possible, the twin engines and their electrical systems should be largely separated. Twin batteries fed by twin alternators should be used. All ancelleries should be wired to both systems so both can provide electricity for the lights.

Unsolved Problems:

  • How to connect the gearchange to the rear engine without aditional lever points.
  • How to connect and disconnect either gearbox from the gearchange.
  • How to turn off the acceleration jet in the engine not being used.

Commercially available 4wd kits

Louis Barbour
UK based manufacturer who uses a special chassis and good quality drivetrain. The special chassis could give some problems with type approval in some countries.

Voisin
French manufacturer who used largely standard bits. Production has stopped but cars occasionally come up for sale.

Weber
Swiss builter of 5 speed 2cv gearboxes also offered a special gearbox (kit) with output shaft at the rear.


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