They were only fitted to estates. ABS made no difference. I had the
same problem on my old 405 a couple of years ago. Went to the scrappy
and got one for nothing--so to speak!!

The rear brake pressure regulator is there to adjust the amount of braking
effort applied to the rear brakes depending on the load the vehicle is
carrying.
The purpose of the spring is to apply the force to move the regulator valve.
Once the valve has moved further movement of the suspension could cause the
link to snap if it was just a rod hence a spring. You can use any spring
that is the length to just be in tension between the unit and the suspension
under no load and of the same gauge. It is possible to braze a piece of wire
on the replace the broken part of the spring. This is usually the hook at
the suspension end. You could try going to your friendly Peugeot spares
dealer and asking to measure the spring. I guess this is not possible as
most parts for Peugeots seem to be special order these days. The 406 is also
fitted with a similar device.

Mike

Hi

What is basicly does is control the amount of braking force to the rear
wheels depending on the load on the rear suspension.

If the boot is empty then the rear of the car will be lighter & the rear
wheels will be more prone to locking, When the suspension at the rear rises
because the front has dropped as the brakes are slammed on the valve
reduces the flow of brake fluid to the rear & helps stop the wheels locking
up.

If the boot is loaded up with stuff then the rear of the car will be lower,
The valve will now let more fluid flow to the rear wheels because theres
more weight over the back wheels & theres less chance of them locking.

Hope that helps explain things clearer.

It has nothing to do with the ABS as such. It regulates the amount of
pressure needed to work the back brakes in accordance with the amount
of load in the back of the car. The more load in the back the more
"power" to the rear brakes.