Xantia Brake mod

Mads · Unread post by **Mads** » 09 Apr 2007, 10:15

After my better half complained that the brakes in our Xantia were too spongy and less responsive than those in the C3, I finally worked up the courage to suggest the spring replacement mod (She is a working environment safety ingeneer, so "mods" are rather hard to get approved

)

Well. after convincing her that the mod were completely safe and easy (30min) I proceeded to actually get it done only to find, or should I say not to find the plastic gizmo which should be connected to the back side of the brake pedal

I could only find an iron rod bolted to the brake pedal which disappear into the engine compartment and directly into what I believe is the dosure valve..

Before I admit defeat, could anyone please confirm that I am not just way off in my search for the plastic spring assembly?

Thanks in advance

DickieG · Unread post by **DickieG** » 09 Apr 2007, 10:31

The spring is held within a plastic cylinder which is found about half way up the brake pedal arm. To remove it you pull it towards the front of the vehicle which entails lifting up the pedal as far as it will go to gain clearance.

For some strange reason when I've tried to remove the cylinder on MK2 models its been well and truly wedged in requiring some levering to get it out, whereas on MK1's its just pulled

Mads · Unread post by **Mads** » 09 Apr 2007, 11:24

Hmm.. thanks. I think that is exactly where I have been looking, but I'll have another look around later on.

citronut · Unread post by **citronut** » 09 Apr 2007, 11:43

if this devise was missing from the under side of you pedel,your pedel would not contact the dozer valve at all,unless someone has fitted something ellss
regards malcolm

AndersDK · Unread post by **AndersDK** » 09 Apr 2007, 13:36

Mads -

What exactly do you mean with 'spongy' brakes on the xantia brake pedal ?
As strictly taken it should not be possible on a high pressure brakes sytem. Instead you get delays from pressing the pedal to the braking occurs. This will happen if air is in the brakes, front flexible hoses are shot, or the rear calipers flexes on the arm (surface contact corrosion).

TBH I dont think you will find the spring gizmo on danish LHD vehicles, but I may be wrong, touch wood, god forbid me, x-ed fingers and please Simon no pages & pages of silly Citroen manuals copied ...

Unread post by **RichardW** » 09 Apr 2007, 15:47

I think you're right Anders - the spring cannister is only on RHD Xantias. The brakes do a feel a bit odd with the spring in, and can make it difficult to achieve smooth braking. Not Mads problem though, as he has no spring...!

Mads · Unread post by **Mads** » 09 Apr 2007, 18:02

Right! That makes sense.

What I mean is that the responsiveness of the brakes is less than that of the C3, i.e. you have to press the pedal further and harder to get good brake action.. (Very nice brakes on the C3 8) )

Well, guess I need to look for some better brake pads instead

Thank you all anyhow

Mandrake · Unread post by **Mandrake** » 09 Apr 2007, 20:11

AndersDK wrote:Mads -

What exactly do you mean with 'spongy' brakes on the xantia brake pedal ?
As strictly taken it should not be possible on a high pressure brakes sytem. Instead you get delays from pressing the pedal to the braking occurs. This will happen if air is in the brakes, front flexible hoses are shot, or the rear calipers flexes on the arm (surface contact corrosion).

Can you elaborate on "front flexible hoses are shot" ? Are you talking about interally collapsed front hoses ? Do you think they could effect 'sharpness' of braking action ? The brakes on my Xantia have always been inferior to the other two Xantia's we have, no matter how much work I have done to them, and I was beginning to wonder if the front flexible hoses could be causing it.

TBH I dont think you will find the spring gizmo on danish LHD vehicles, but I may be wrong, touch wood, god forbid me, x-ed fingers and please Simon no pages & pages of silly Citroen manuals copied ...

No need to worry, I don't have those pages !!

But yes you are right, LHD (some ? all ?) do not have the spring unit, I have seen pictures of it, and they just have a link rod which dissapears through the bulkhead out of sight to the doseur valve.

Regards,
Simon

Mads · Unread post by **Mads** » 09 Apr 2007, 20:27

Lack of 'Sharpness' as Mandrake describes it is a good description for my problem. My car defenitly only got the link rod setup, so no help there..

Never changed the flexible hoses. I see how they may get 'loose' over time like an old rubber band.., anyone had positive experience doing them?

Unread post by **CitroJim** » 09 Apr 2007, 20:36

Mandrake wrote:The brakes on my Xantia have always been inferior to the other two Xantia's we have, no matter how much work I have done to them, and I was beginning to wonder if the front flexible hoses could be causing it.

Funny you should say that Simon. I have a foot in both camps as it were, my Mk1 has the brake mod and the brakes are very sharp, positive and responsive. To me, perfect.

I don't think flexible hoses would cause it. By logic, they would give the same symptoms as air in the system (delay) unless they're really bad and ballooning under braking pressure.

My Mk2 has not had the mod done (yet - too may other things to get done first

) and the brakes feel totally different and indeed do feel inferior to the Mk1 brakes. They're not, it is just a feeling that seems to come from the spring being present and the car as a whole having a totally different personality. I do feel though that in the Mk2 I have to press the pedal significantly harder and further to achieve the same braking action but then again it is usually from a higher speed

Whilst I cannot reason why, does having hydractive make any difference? Not perhaps to outright braking power but to feel?

I must do the mod soon and see how it changes things.

Unread post by **CitroJim** » 09 Apr 2007, 20:41

Mads wrote:Never changed the flexible hoses. I see how they may get 'loose' over time like an old rubber band.., anyone had positive experience doing them?

An easy job

One of the great advantages of LHM is that the brake line unions do not corrode like those using ordinary brake fluid so it is always easy (ish) to remove the flexis and for that matter, crack bleed nipples open.

Remove the front calipers complete to change hoses to avoid hose "wind-up" Spin the caliper around the end of the pipe until almost fully tightened, replace caliper and then finally "nip up" the hose unions.

Mandrake · Unread post by **Mandrake** » 09 Apr 2007, 20:52

citrojim wrote:
Mandrake wrote:The brakes on my Xantia have always been inferior to the other two Xantia's we have, no matter how much work I have done to them, and I was beginning to wonder if the front flexible hoses could be causing it.
Funny you should say that Simon. I have a foot in both camps as it were, my Mk1 has the brake mod and the brakes are very sharp, positive and responsive. To me, perfect.

As are our other two Xantia's - a 1993 and a 1994 which have both had the spring mod done. Lovely sharp sensitive brakes just like the GS/CX.

I don't think flexible hoses would cause it. By logic, they would give the same symptoms as air in the system (delay) unless they're really bad and ballooning under braking pressure.

Well, when brake hoses go they don't "balloon" under pressure externally, they delaminate inside so that the inside layer "collapses" under the vacuum which occurs when you let the brake off. In extreme cases it can cause the brakes to stick on slightly because the oil flow is blocked from completely returning.

Every time you apply the brakes the pressure then has to "reinflate" the inside layer that has collapsed, and I would imagine that the effect would be similar to having a lot of air in the brake lines.

My Mk2 has not had the mod done (yet - too may other things to get done first ) and the brakes feel totally different and indeed do feel inferior to the Mk1 brakes. They're not, it is just a feeling that seems to come from the spring being present and the car as a whole having a totally different personality. I do feel though that in the Mk2 I have to press the pedal significantly harder and further to achieve the same braking action but then again it is usually from a higher speed

Well mine is a '97 Mk1, and it HAS had the pedal spring mod done, its also had new front discs, new pads all around etc etc, everything seems in order, if I press the pedal HARD I can do an emergency stop just fine, its just in normal every day braking the brakes seem very dull and ineffectual until you press relatively hard.

I also notice that the "sensitivity" of the brakes (response to light to moderate pedal pressure) actually varies on a day by day basis - some days it is relatively good (but never as good as the other two cars that are pinsharp sensitive) and other days it is dull and insensitive. The pedal action also changes too - on good days the pedal is firm, on poor days the pedal feels a bit soft and spongy.

Got me beat, thats for sure. About the only unresolved problem that may be affecting the brakes is I'm pretty sure that I have a faulty hydraulic pump which is sucking in air via the pulley shaft seal, (and also affecting the ride quality) but I won't know for sure if it has any effect on the brakes until I replace it shortly... if that doesn't help I will be looking at the front brake hoses.

Whilst I cannot reason why, does having hydractive make any difference? Not perhaps to outright braking power but to feel?

I don't see that it should have any effect - provided the anti-sink sphere is in good condition, and mine is new. But as it happens, my Xantia is Hydractive 2 and the other two aren't....

I must do the mod soon and see how it changes things.

Well worth doing!

Regards,
Simon

Mads · Unread post by **Mads** » 09 Apr 2007, 20:54

Yes, they should be easy enough to do. Still having nightmares about changing brake hoses on my old ZX.. ended up having to drill out the broken bleed nipples

Long live LHM 8)

Getting back to the sloppy brakes, I still think it could make sense that old, slightly more "flexible" hoses, will give a little less sharp pressure rise (not nearly as bad as air) when the brakes are applied, hence producing a weaker and less sharp response..

Mandrake · Unread post by **Mandrake** » 09 Apr 2007, 21:03

Mads wrote: Getting back to the sloppy brakes, I still think it could make sense that old, slightly more "flexible" hoses, will give a little less sharp pressure rise (not nearly as bad as air) when the brakes are applied, hence producing a weaker and less sharp response..

Yeah, thats my feeling too. (See my comments about internal delamination)

I notice if I press the brake pedal hard for the first time that day, it feels quite soft and spongy but if I hold it down it starts pushing back at me and then if I release and apply it again the pedal feels a lot firmer the second and third time.

And if I fully depress the pedal like this a few times before setting off, the brakes definately feel a bit sharper and more sensitive than they otherwise would have - and because I have done this at a stationary speed it can't be due to bedding the pads in.

The hose being stretched back to normal shape would fit these symptoms, because if it was air in the lines simply pressing the pedal a few times would probably not expell it. (Well, unless the air was BEFORE the brake doseur valve, rather than in the dead end line to the brakes

)

Another slim possibility is simply that the front pistons are a bit seized and that the slight movement that comes from fully depressing the brakes a few times is freeing them up slightly. Does anyone know how to remove the pistons in the front brakes or whether its even possible ? (Due to the handbrake adjuster being in the way)

Regards,
Simon

Mads · Unread post by **Mads** » 09 Apr 2007, 21:26

Thanks for the input. I decided it is time for action; New disks, pads and hoses on order. Fingers crossed, keep you posted on the effect. Wife will have the final word.. Can't believe me actually saying that