james,
it may well be worth popping the rear drum off for a look, give yourself plenty time to do it- ie dont start at 5 on Sunday if your needing it on Monday morning.

Every late model 2cv ive ever seen has the rear pivots for the brakes seized as they had been assembled without grease, strangely they all passed MOT and contrary to popular belief they do have a huge effect on how the car behaves when braking. The effort exerted by the rears causes the car to sit down at the back rather than pitching forward like the Herge cartoon


if the car has been stood dormant for a year or so that's when the shoes start to de laminate

and whats the worst that can happen...you have brakes that work?......hmm actually on 2nd thoughts

Isn't the anti-dive characteristic more down to leading arms at the front?

I would add another vote for take them off and have a look. I've never taken one apart that wasn't knackered! As Sean said, the rear pivots seize (being ~1" pins, rather than knife-edge type pivots on every other brake I've had apart) and due to the tiny amount of movement needed, I think the shoes tend to try to flex, rather than the pivot moving. This leads to the linings coming away from the metal part and, well, just have a look! My Dyane passed three MOTs with no problems with all the shoes delaminated and one piston in each cylinder seized solid..!

I don't think you need to go cutting holes in anything to get the rear drum off - the idea behind removing the centre of a wheel is to give you a means of undoing the driveshaft nut without the front hub rotating. The rear hub nut is screwed onto the stub on the end of the radius arm, which obviously can't turn. Take the wheel off, ensure the end of the arm is supported, and remove the nut. It's 44mm as mentioned, but you can get away with (I think) 1 3/4" if that's all you can find. The brake drum can usually then be "wiggled" off if you put the wheel back on and use that to hold onto.

Russ,if the disks were on the leading arm then the torque reaction would have the arms trying to tuck under, one of the reasons the brakes had to be on the 'Box rather than Hub

the interlinked suspension doesn't help the pitching- as the front dives it pulls up the rear. Good brakes at the rear has the torque reaction lifting the trailing arm and reducing the pitch- makes for a nice handling car - stops it wobbling about in corners as you go in on the brakes.

I've been trying to think of an expression to describe that noise.

That will do admirally.

Russell,
might be, if the brakes were mounted at the wheel end of the driveshaft.

But since they're inboard, all braking torque at the front end is transferred from the calipers/brake backplates to the engine/gearbox unit, then via the engine/gearbox mounts to the chassis.
This can be confirmed by driving with the gearbox mount bolts loose and braking hard...

ken

I'd agree with Luke and Sean, in that the rear brakes on A series cars are often badly neglected.
The reason they can pass an MOT test with the rear brakes well below par is because the front brakes can make up for the low readings on the rear.
When I took a drum brake Dyane for MOT recently, which had just had all its brakes rebuilt, the tester commented that the overall braking efficiency of 71% was higher than that of many modern cars.

When working correctly, rear brakes should contribute 40% of the total braking effort,so 'around' 200 kg at the rear and 300kg at the front.

ken

Rear brake shoes ''last forever'' since the cylinders doesn't work or the mounting points are rusted together. The rear is not really designed to brake the car but to steer the car.

erm
so why did they bother?
how do brakes steer the car?

and if you can explain that, then go back to the beginning of the post... how do they do it if they dont work?

If the rear is not working at all but the front has full effect, the rear of the car would try to swing around to the front. By the rear braking just a fraction, the car is braking in a straight line even in corners. A models, GS and CX etc. have little braking power available on the rear as almost all braking is done from the front brakes. The rear is just ''steering'' the car.