Peugeot 106 Master Cylinder

[wheeler]

Have you tried a Peugeot dealer for a master cylinder ?

They are no longer available from the factory

[Pete731]

The front brakes have been checked and are all ok.

I have had someone else check the Peugeot parts lookup by VIN and as in an earlier post only Bosch Bendix or Teves systems show up and not Ate so I am not sure what is going on there.

[MattBLancs]

Sorry for a daft question, but how have you established the rears are coming on before the fronts?
The rear brakes contribute a small amount to slowing the car, quite surprised if you can feel it on the road

[Pete731]

Good question Let me expand. When I apply the brakes the rear of the car dips as if I am staring to apply the handbrake. I can feel the rear braking working more than perhaps it should especially on a loose surface (my drive). But yes, you are right, the effect on the road is much less. It is as if the braking effort at the front is reduced but it seems to stop ok. I wouldn't say the brakes are bad overall at stopping. I either have too much effort at the back or not enough at the front. I am going to change the front discs and pads as a matter of course.

[myglaren]

Could it be the brake balancing valve misbehaving?

[Pete731]

I didn't think it had one but I stand to be corrected.

[Stickyfinger]

Are you sure the rear cylinders are the correct ones ?....an AX should never "dip" at the rear. TBH the rear brakes only really work if the car has a couple of people in the back.

[Pete731]

Are you sure the rear cylinders are the correct ones ?

Nope! I am trying to identify which ones are the correct ones which is where I am having some difficulty.

[PaulC5]

If the rear cylinders have a larger diameter they will apply more force on the rear brakes than if the diameter was smaller. Think of it as a pressure, as an example, if 200 psi, for each square inch there is 200 pounds force so if 1 square inch you get 200 pounds but if 2 square inches you get 400 pounds. I once fit larger diameter front calipers to a Maxi as well as a larger diameter master cylinder (all from an Allegro in a scrap yard) and the brakes were a lot better at stopping.

[Pete731]

The smallest diameter option is 19mm so If I measure them and find them to be that size then the problem lies elsewhere. If they are larger then that may indeed be the problem, although as of yet I am unable to determine their correct size by various lookup methods including looking up by VIN.

[Stickyfinger]

Just to ask.....is the rear brake compensator/Pressure Regulator seized/rusted up ??

[Pete731]

I think only cars with ABS had those didn't they? Not 100% sure. No ABS on mine.

[Pete731]

My Haynes manual indicates that on non ABS models the pressure regulating valves are integral with the rear cylinders and the cylinders must not be dismantled. If a fault is suspected then the complete cylinders must be renewed. That means I can't measure them, or if I do I would have to replace them

[Pete731]

Which would mean that if the rear cylinders I have had fitted where meant for ABS models there would be no pressure regulation to the rear. That would explain it if that is what has happened.

[Pete731]

The pistons in the calipers are not seized but I haven't yet checked the hoses. The front discs and pads have now been changed and I am waiting for the pads to fully bed in to see if the braking at the front is improved, but it still feels like the rears are still engaging before the fronts.

I am not 100% sure which rear wheel cylinders have been fitted but research has shown that non-abs cylinders have internal valving for brake proportioning while rear cylinders for abs models have no valving as a compensator is fitted to the rear axle. So if abs cylinders have been fitted there would be no proportioning to the rear at all. I may order some non-abs cylinders and get them fitted.