This article about how to change a king pin has been written by 2CViking.

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This is purely my way of doing it. Haynes and other manuals also describe how to do it, but some vital information is missing.
You will need a set of king pin fitting tools like the ones shown below.


Jack the 2CV up on 2 solid stands.
The best jacking points on a 2CV at the front are the left and right steering rack bolts underneath the chassis.
In the rear, the best points are the axle bolts on the left and right side. If both wheels are to be lifted of the ground, use a solid piece of hardwood between the bolts.

I have seen older rusted chassis bending when the 2CV is lifted in incorrect places. NEVER lift a 2CV on the front cross bar underneath the engine mounts.

The original jack is not suited on not solid ground. The 2CV has a bad habit of rolling forward or backward when one wheel is lifted off the ground. It is better to get a scissor jack from a wrecker’s yard, place it underneath the 2 bolts holding the steering rack or the rear axle. Make up a square piece of solid hardwood and place between the ground and the jack. No more worries.

Remove the wheel, drive-shaft and grease nipple.
Lift the swing arm up a fraction and put another solid stand underneath, rest the swing arm on the stand close to the hub (where the grease nipple was located).
Open the folded over bottom screw plug with a cold chisel. Be gentle not to ruin the thread inside the hub.
Use tool no 1 to unscrew the plug.
Insert tool no 2 and slide it inside the king pin from underneath until firm contact with the top grease/dust cap.
Knock the rod with a big hammer to remove the top cap.
If you don’t have a vice, it is now time to clean the exposed king pin and to grind away the small metal chips which held the cap in place. Use a small grinding stone on your drill. Use the new cap from the new king pin set to measure the hole. The new cap MUST fit perfectly with a tight fit.
Clean away all the metal dust
Use tool no 3 and 4 as a drift and push the old king pin out with the shock technique. A big hammer is required. If the king pin drops out too easily, the swing arm hole is too big and the new pin will not hold. New swing arm is needed.
If the pin won’t move, DON’T use heat as the swing arm hole will expand and not come back to the same size. Apply the right amount of shock and the pin will come out.
Undo the steering ball joint arms 2 bolts and remove the hub etc. Cleaning time. Cover the wheel bearings to avoid any cleaning fluid flowing in to them.
Place the hub in a vice upside down and remove the lower bush first with tool no. 5. To protect the lower screw plugs thread, push the bush out away from the thread, not past the thread.
Turn the hub and push out the top bush, same tool.
Cleaning time again including the new king pin set.
Check the hub for groves where the shims are located. Clean with a file to remove uneven surfaces.

FITTING THE BUSHES
It is very important that the new bushes are lined up correctly.
Start with the lower bush first. Use tool no. 5, push the bush in from the top (not the bottom, it can ruin the thread)
The lower bush must not protrude above the whole. It must not have any contact with the shims.
Fitting the top bush correctly is mighty important. If it tilts on the way in, the king pin hub can not swirl without biting into the walls of the bush. Use the old king pin and not the dummy tool no 6. Slide the old king pin in through the lower bush to the top position. Very gently tap the top bush with a plastic hammer until the bush begins to enter the hole. The old king pin will prevent the bush from tilting. Remove the old king pin, insert tool no. 6. Tap the bush home.
Same for the top bush, make sure that the bush is not below the hole having any contact with swing arm.
If the bushes are not located correctly, it is impossible to measure and fit the correct shims.

FITTING THE CORRECT SHIMS
Before fitting the new king pin, fit shims, grease washer and cup on the hub and place the hub on the arm. Measure the play between the swing arm and the hub using feeler gauges. Citroën’s recommendation is 0.1-0.4 mm between the hub and the swing arm right underneath the top bush. Aim for 0.1mm as 0.4mm is too much play in my opinion. Too much movement will wear out the top bush quicker. The shims will determine the play.

FITTING THE KING PIN
Use the old king pin to line up the hub and the shims by inserting the old pin from underneath. Push the pin through the shims and in to the swing arm hole. Tap the old king pin a bit so it enter the swing arm hole. Grease the new king pin, place it in to the top bush. Make sure the grease holes in the pin are pointing the correct way. Use tool no. 4 to drive the king pin through the swing arm. At the same time hold the old king pin in place, must not drop out as it is lining up the shims. While driving the new king pin in, check that the hub can turn. It is very important that the shims are not sliding around, the new king pin coming down can easily hit the edges of the shims. When home the king pin should line up so the top is equal to the top of the top bush. If too fare below, the bottom screw plug can’t be fitted correctly. Fit the bottom screw cap and peen it over. Locate the top grease/dust cap. Flatten it with a drift and peen it over in 4 places. Fit the grease nipple and grease the king pin. Check that the grease/dust cap is not pushed out when greasing the kin pin.

Congratulation you have fitted a king pin correctly. If the king pin went through the swing arm to easy, the risk is that the king pin will move upwards and knock out the grease/dust cap and hit the drive shaft. Fit a new swing arm.

MAINTENANCE
The king pin design is 60 year old technology. Modern driving is very different from the old days where cars did very few kilometers. King pins should be greased every 1500 km to avoid being worn out. The grease is pushed away and dry king pins don’t last very long. The top bush in particular is very small and needs to be greased often.

WORN OUT SWING ARMS
After replacing the king pins many times, the king pin housing on the swing arm becomes too big. Every time a new king pin is pushed through the swing arm, it removes a tiny amount of metal from inside the hole, making the housing hole a fraction bigger. Eventually new king pins can’t be fitted correctly as they are too lose. The only option is to replace the swing arm which is silly. New swing arm are no longer produced and we should preserve current stock from rust or damaged swing arms. I am in the process of finding a manufacture who is willing to produce an oversized king pin, we can use on swing arms with too big holes. More later.

Tool measurements in mm
3. 7x 16x24
4. 4x16x24
5. 16x20
6. 16x20

If the explanation is not clear or confusing, please feel free to ask.

Happy working