From a safety standpoint, I’ve felt for some time now that my Traction Avant 11BN needs an upgrade to its braking system, which is originally equipped with a master cylinder with a single pressure chamber.
I’d like to convert the system to a diagonally split braking system with a toothed master cylinder featuring two pressure chambers. Starting in (I think) 1968, this has been mandatory for all cars, and it can be either cross-split or front/rear split (provided the brake types are the same).
I’m going with a diagonally split braking system because the rear brakes only contribute about 20% to braking, so if one system fails, you’re better off with one working front brake plus a drum brake on the other side. That’s much better than having to rely on two rear brakes without any front brakes if one system fails.
For example, on the Citroën HY, an upgrade was made during its production run from a single-circuit braking system to a dual-circuit braking system.
The original single master cylinders on a Traction Avant 11BN and a HY are identical.
Therefore, the HY’s dual master cylinder should simply fit into the bulkhead of my Citroën 11BN.
However, a long dual master cylinder won’t just fit under the cover in the left jambonneau (dashboard) where the single master cylinder is located.
Because of the extra length of a dual master cylinder, it protrudes so far forward that the existing hole for the cover must be enlarged by about 6 centimeters.
In principle, that’s possible, and it can be done neatly.
However, the dual master cylinder would then protrude slightly above the dashboard at the front. And that’s not the intention.
So the simple solution would be to incorporate the protruding part into the dashboard by extending the dashboard upward at the point where the master cylinder sticks out.
First, reinforce the area around the hole to be cut, and then create a domed cover that curves upward over the front of the master cylinder.
So I ordered the tandem HY master cylinder and all the necessary additional brake parts.
Two brake lines will then run from the master cylinder,
1 for L-front + R-rear
And the other one for R-front and L-rear.
It’ll take a bit of figuring out where to place the 3-way couplers, but they can actually all go in the same spot where the 2-way distributor is now: simply on the left bulkhead, where the brake lines currently converge.
By the way, all the brake lines will be replaced, and the flexible section on the left near the rear axle will be doubled up, just like the brake lines for both the rear and front wheels.
Everything will then come together on the left jambonneau, on the engine side.
I still need to check whether the clutch cable runs right past that spot. If it does, I’ll have to reposition the brake lines slightly.
Another point to note: A reservoir tank with two separate compartments for the DOT 3 brake fluid will be installed:
THIS PROJECT IS PLANNED FOR EXECUTION IN THE FALL OF 2026.
In my experience, this upgrade should be executed for any Traction Avant, since it makes the car way more reliable and much safer for road travels.
I intend to make a kit for DIY with all of the materials, and supply serivces to execute this for others as well.
The price for this upgrade will be around Eur 750 for just the materials, and around Eur 1500 for the complete execution, including materials.
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mail: info@Jantec.nl