Peugeot 406 Brakes

[cwhaley]

I'll brave it and take a look under there. It really is hidden away high up into the dash maybe the spring has become slack over time or the assembly/bracket is loose.

On the Gazelle, the pedal connects directly to the pushrod which goes into the master cylinder just behind the firewall. I can remove it with ease (think it's just a circlip stopping the pushrod coming out), as I did when I rebuilt a NOS Lockheed cylinder.

 

[carmanmemoranda]

Is the brake pedal free to move? Restricted in any way? Some, but not excessive, side to side movement ?

 

[cwhaley]

Is the brake pedal free to move? Restricted in any way? Some, but not excessive, side to side movement ?

There is a little play in the pedal yes -- I can 'wobble' it from side to side to a degree. It sounds mildly 'loose' but has never caused concern as the braking power has always been satisfactory and unchanged.

 

[carmanmemoranda]

There is a little play in the pedal yes -- I can 'wobble' it from side to side to a degree. It sounds mildly 'loose' but has never caused concern as the braking power has always been satisfactory and unchanged.

The other possible thing to stop the pedal returning would be lack of free movement (too tight). But sounds like its free to move, so now need to find why it doesnt move (back to its stop point)

 

[Burnerman]

The only instance I recall which could be similar takes me back to the '80's concerning a Transit minibus, (petrol.)
There was a constant hissing from the pedal box area - this ceased when the pedal was lifted up a little. The hissing was obviously the servo doing it's job, but I don't know if the brakes were affected at all.
Anyway, back to Ford and it came back with a pedal at the very top of it's travel and no hissing......what work was done is unknown but I guess it was fitted with a new master cylinder.
John

 

[Avocet]

There's usually a spring (sometimes two) inside the master cylinder. I wonder if you've got a broken spring?

 

[cwhaley]

The only instance I recall which could be similar takes me back to the '80's concerning a Transit minibus, (petrol.)
There was a constant hissing from the pedal box area - this ceased when the pedal was lifted up a little. The hissing was obviously the servo doing it's job, but I don't know if the brakes were affected at all.
Anyway, back to Ford and it came back with a pedal at the very top of it's travel and no hissing......what work was done is unknown but I guess it was fitted with a new master cylinder.
John

These old HDis can sound a bit like a tractor when they're running, so I'll do my best to listen out for it. I did detect an air leak on the turbo pipe once this way, but it was fairly obvious.

Think I'll have to have the bonnet up, engine running playing with the pedal. Thanks for the pointer

 

[cwhaley]

There's usually a spring (sometimes two) inside the master cylinder. I wonder if you've got a broken spring?

I think I need to examine the set-up for it as it's far more complex than I'm comfortable, with the cylinder and servo being on the opposite side of the bay to the pedal.

The brakes are good, otherwise.

 

[Avocet]

I think I need to examine the set-up for it as it's far more complex than I'm comfortable, with the cylinder and servo being on the opposite side of the bay to the pedal.

The brakes are good, otherwise.

That's common on right hand drive versions of cars that were originally designed as left hand drive. There will probably be a hoofing great bar, running across the bulkhead, behind the dashboard, to take the pedal movement from the pedal on the right, to the master cylinder on the left. There's not much to go wrong with the bar, really. There will be a bearing at each end, of course, but if the pedal moves freely, I doubt there will be anything wrong with the bearings.
At the master cylinder end, there is likely to be a clevis pin to connect the bar to the pushrod in the master cylinder. If it is accessible, and you can take the clevis pin out, you'll be able to check whether the bar moves freely, but I'm pretty certain it will.

 

[cwhaley]

That's common on right hand drive versions of cars that were originally designed as left hand drive. There will probably be a hoofing great bar, running across the bulkhead, behind the dashboard, to take the pedal movement from the pedal on the right, to the master cylinder on the left. There's not much to go wrong with the bar, really. There will be a bearing at each end, of course, but if the pedal moves freely, I doubt there will be anything wrong with the bearings.
At the master cylinder end, there is likely to be a clevis pin to connect the bar to the pushrod in the master cylinder. If it is accessible, and you can take the clevis pin out, you'll be able to check whether the bar moves freely, but I'm pretty certain it will.

Yes I think I recall seeing the linkages when I disabled the EGR (purely for the benefit of the health of the engine). They were on the firewall just below the scuttle panel

What you've explained makes sense. I'll have a look to see what's accessible.

One question you may or may not know the answer to... if I apply pressure to the brake pedal with the ignition on and then start the engine, should the pedal sink a bit? I recall reading somewhere that this indicates the servo is working.

 

[Stivino]

That's common on right hand drive versions of cars that were originally designed as left hand drive

Some of the old Yugos used to have that and, if the passenger was stretching in their seat and pushing against the bulkhead with their feet, it was possible to apply the brake.

 

[Avocet]

Yes I think I recall seeing the linkages when I disabled the EGR (purely for the benefit of the health of the engine). They were on the firewall just below the scuttle panel

What you've explained makes sense. I'll have a look to see what's accessible.

One question you may or may not know the answer to... if I apply pressure to the brake pedal with the ignition on and then start the engine, should the pedal sink a bit? I recall reading somewhere that this indicates the servo is working.

Yes, it absolutely should. However, to do it properly, you need to exhaust the servo first. With the engine not running, press the brake half a dozen times. The servo itself (and the tubing to it) will store some vacuum for a while after shutting the engine down. The intention is that if your engine stalls, you will still get a few brake applications before you run out of servo assistance. Pressing the pedal half a dozen times without the engine running, will use up all that vacuum and the pedal should end up feeling pretty hard.

At that point, rest your foot on the brake pedal gently and start the engine, within about a second of startup, you should feel the pedal sink under the weight of your foot.

That indicates that the servo and the vacuum pump (if it's a diesel) are working correctly. However, it doesn't confirm anything about the state of the master cylinder. In days gone by, you used to be able to press the brake pedal really hard, and a slow sinking of the pedal meant either master or wheel cylinder problems. However, on some ABS-equipped Peugeots, (and other marques), I have noticed that the pedal will sink slowly under those conditions anyway - even on a new car.

 

[Avocet]

Some of the old Yugos used have that and, if the passenger was stretching in their seat and pushing against the bulkhead with their feet, it was possible to apply the brake.

Yes, I'd heard that. Handy for nervous passengers who apply a "phantom footbrake" when they start panicking!

 

[martygturner]

Basics first, check the caliper pistons move freely bleed the brakes, rust or rubber particles of a deteriorating hose makes an excellent one way valve in a brake system.

 

[cwhaley]

Basics first, check the caliper pistons move freely bleed the brakes, rust or rubber particles of a deteriorating hose makes an excellent one way valve in a brake system.

All calipers are fine and freely moving (the rear n/side was stuck, s a brand new one fitted two weeks ago) and all hoses are in good condition. Nothing is binding now and the car rolls freely. I think the issue lies somewhere else.