Saxo brake issue

[Rockettvr]

Hi all
I'm struggling to find the answer to a brake issue on my sons saxo 1.1
We've had the car a few months and Tbh the brakes have never been great - needing a lot of pressure on the pedal to get any braking response. A couple of weeks back the brakes went altogether - master cylinder failure. A new one ordered and fitted, bled the brakes but found a failed slave on one of the rear drums(probably why the brakes have never been good) Fitted new slave , bled brakes again but the rear drums are not working correctly - the fronts are great locking up when the pedal is pushed but the rears barely have any grab to them - even when the pedal is pushed fully down I can turn the wheels by hand although with some effort.
I've bled the system several times using an easy bleed non return tube , the brake shoes(renewed both sides when slave replaced) are adjusted as far as possible without actually rubbing and the hand brake works really well needing only 3 clicks to lock the wheels solid.
I've had the drums off and the slave cylinders expand when the brake pedal is depressed
I thought it may be a faulty master cylinder (although new) so fitted another but the same symptoms persist.
In short the brakes are working well except that the master cylinder is exerting some but not enough pressure to the rear wheel cylinders.
Am I missing something ???
Any thoughts gratefully received
Thanks Ron

[GreenV8S]

Did the pedal behave sensible when you bled the rear brakes i.e. that the pedal feels solid when the bleed valves are closed and you can feel if soften very obviously when you open the bleed valve? Bleeding the rear should feel similar to bleeding the front and if it doesn't, you've got a problem - either a blockage or an air lock or a jammed piston. Did you watch the condition of the fluid coming out and see the old fluid expelled followed by good clean fluid free of air bubbles? You don't say how familiar you are with bleeding brakes - unless you follow a good technique it's possible to end up sucking some air back into the cylinder which could cause symptoms like these.

Does that car have a dedicated circuit for the rear brakes? Some cars do, using a tandem master cylinder - if the rear slaves are connected to the same point on the master as the front then you can probably rule out master cylinder issues.

You should have a bias valve in series with the line to the rear brakes. If this has seized of been jammed by debris this it could obstruct the rear circuit. Worth locating it - you might end up needing to disconnect it to check for blockages as a last resort. For example shredded remains of a seal from the damaged master could have been flushed through the line by a leaky slave.

[SebringMan]

Have you tried compressing the brake compensator to see if the rear brakes work ; this is designed to reduce the braking effort if the rear becomes light. What year is the Saxo? I think anything before 1998 had the compensator on the rear beam.

These can also seize up but can be worked free.

[Rockettvr]

Thanks for the replies. It was indeed the rear brake compensator- I wasn't aware that the saxo came with one - all sorted now thanks