Citroën rear suspension (3):
Brekina
Page created on 18/01/2024.
The principle
Here again, the aim is the same as for the Acadiane Brekina, but the means are different. There are two main objectives: to simplify operations and to represent the inertia dampers of the Citroën suspension. These typical elements, called “batteurs” (beaters) by Citroën, were fitted to the Dyane until 1972, whereas the Acadiane never received them. They are particularly noticeable at the rear, but they also exist at the front.
I learnt from my research that the beaters were quite heavy (around 8 kg). On reflection, a lot of mass was needed for inertia to play its role.
Cross-section of a 2CV rear beater.
Photo Documentation Citroën.
This time, there are no suspension arms. A vertical rod representing the beater is soldered perpendicular to the end of the wheel axle. This “beater” will be inserted directly into the chassis.
As the actual diameter is 65 mm, the diameter of the beater rod will be 0.75 mm, rounded up to 0.8, and that of the axle, 1 mm (original value).
It would be advisable to remove the large protrusion from the hub, and consequently to drill the axle deeper, with the risk of damaging the wheels, which goes against the aim of simplicity.
An idea emerged for the front wheels: they could pivot around the beater. But, in order to respect the look of the steered wheels, the axles would have to be tilted — by how much? That remains to be determined.
On the other hand, at the rear, the most difficult thing will undoubtedly be to keep the wheels parallel…
In fact, I consider two solutions. The first, in the centre of the image below, is the simplest: the beaters are inserted into the interior fittings, because there isn’t enough material in the chassis. The second, on the left, is a little more complicated, requiring the protruding wheel hubs to be levelled, and a polystyrene plate added into which the beaters will be fixed. At the cost of this added complexity, the look will be much better rendered.
On the right, the initial situation (very schematic).
I finally chose the second solution.
The operations
Disassembly
Disassembly here is less straightforward than on the Acadiane, as you have to pull out a sliding tenon like a drawer at the rear, representing the number plate. For the rest, see the previous page.
Machining the chassis and interior fittings
I level the old rear axle supports on the chassis. Flush cutters are ideal for this.
I strip the paint from under the rear wing returns of the interior fittings. I prepare polystyrene rectangles 6.7 × 2.8, 1 mm thick, then glue them in place. I use Faller Super-Expert liquid glue no. 170490, as the Kibri no. 39996 I tried before gave a poor result.
I drill ⌀ 0.8, depth 2 to 2.5 mm, centre distance 10.6 mm, 5.8 mm from rear edge according to this plan :
Click on the photo for a close-up view.
Note the 0.5 mm thick polystyrene shims placed on either side of the glued parts to ensure correct
tightening in the vice.
Preparing the wheels
In a wooden (better still, epoxy) plate, I machine a blind hole ⌀ 5 × 1 mm, with a milling bit. I place the wheel without its tyre in the hole, inside upwards, then place the whole assembly in the vice of the sensitive mini-drill fitted with a ⌀ 1 mm drill bit. I mark the height of the hub, then adjust the stop to drill into the axle to a depth of 2 mm.
Click on the photo for a close-up view.
Caution: the wheel must be held in the support during operation.
Without modifying the position of the parts, I place a ⌀ 3 milling bit in the chuck and mill the hub to a depth of 1 mm. I deburr, then I do the same for the other wheel.
Click on the photo for a close-up view.
Preparing the nickel silver parts
I cut two 6 mm segments of ⌀ 0.8 mm nickel silver rod (the “beaters”); I round off the ends.
I cut a 14.5 mm long ⌀ 1 mm nickel silver rod. This length is exactly that of the fictitious rear axle pin. I chamfer the ends slightly. I fit the wheels on them to check that the overall width does not exceed 16 mm. When correct, I remove the wheels.
In the same insert as before, I drill two ⌀ 0.8 × 1 mm holes, 10.6 mm apart. I place a segment of ⌀ 0.8 mm rod in each. Perpendicularly, flat on the support, I place and hold (crossed tweezers) the ⌀ 1 mm axle in contact with the previous ones, evening out the overhang on each side. I solder the three pieces with tin-silver.
I degrease and burnish the whole.
Assembly
I place the tyres on the wheels, then mount them on the axle. I test fit the assembly in the chassis and fittings. Note that, for the moment, the fittings and chassis are not correctly assembled.
Before final gluing, some painting: the white plates, Humbrol matt acrylic dark grey no. 32 (black no. 33 would be OK, too); wheel interior, same shade. I scrap off the blue paint that covered the number plate, which reveals the black colour of the part.
I reassemble the body, which gives me a better idea of the final appearance. By adjusting the suspension height, we can represent a car more or less loaded.
Once I’ve found the right height, I disassemble and I cut the axle flush with the “beaters”.
I glue them in place with CA glue, checking the parallelism. All done !
The result
Click on the photo for a closer view of the rear beater. In fact, I find the representation of the suspension arm lacking, however… But I haven’t said my last word!
Click on the photo for a close-up view of the rust that has started to attack the front wing! The reason for the “rust” is that the front wings, painted blue, are part of the orange interior. All it took was a small paint chip to reveal the underlying material.
Respecting the centre-to-centre distance is optional;
Nevertheless, it allows you to make checks
on the car until the last moment,
before cutting the axle definitively.