'Progressive' Brakes on Xantia

MikeO · Post by **MikeO** » 08 Jan 2005, 19:13

Hi Again - the brakes on my 94 Xantia 1.9 T Diesel are fine, in as much as they stop the car efficiently. But they feel a bit odd. When I brake firmly, the braking effect seems to increase, then decrease slightly. This means the car almost 'lurches' to a stop,in a series of cycles, rather than just braking in a normal, linear manner.
It's not ABS cutting in (it's not as rapid or obvious as that), nor is it warped discs (of which I've had some experience on other vehicles). I'm wondering if there's a slight leak in a vacuum hose or something. Any ideas?

Post by **philhoward** » 08 Jan 2005, 19:36

I had that on my first Xantia; changing the accumulator sphere made it a little better for a while, then it came back. After many trips back to the dealer I got it from, he still couldn't fix it, so he had it back (after a big LHM leak from the NSR strut area) and I got a refund (it was still for sale 12 months later). I think the hydraulics on that one were a bit duff; a hydraclean may have helped, though, as it seems to rejuvinate most hydro systems.
Sorry can't be any more help, but had a few suggestions on here including citaerobics.

NiSk · Post by **NiSk** » 08 Jan 2005, 19:57

Start off by changing or charging your accumulator sphere. A Xantia's brakes work by the brake control valve (that thing you operate with your foot) releasing high pressure oil (LHM) out to the brakes. Pulsations in the oil pressure (and hence braking effort) may well be due to an accumulator sphere with very low internal pressure, which needs to be replenished from the high pressure pump after a few seconds of use.
//NiSk

nick · Post by **nick** » 08 Jan 2005, 21:09

If the accumulator sphere is changed and it still does it, try bleeding the rear brakes. My Xantia has always done this on and off since I bought it 5 years ago, bleeding the brakes stops it for 12 months or so.

acrowot · Post by **acrowot** » 08 Jan 2005, 22:01

I had this problem with my Xantia, changing the accumulator sphere made a definate improvment, doing the "citerobics" would cure the problem for 2 or 3 weeks. Finaly I changed the LHM ( inserting Hydroflush initially for 3000 miles )bleeding all brakes each time,I cleaned the filters which were very dirty also. I have had no further problems with the brakes now for well over 12 months.

DarkendViper · Post by **DarkendViper** » 09 Jan 2005, 01:28

I had this problem with my Xantia VSX Estate. I changed all the spheres, and it was still their. Changed fluid a few times. Changed Hydraulic pump and that helped.
One day when I was fitting the original radio back in I noticed that the carpet was damp. After looking behind the brake pedal I noticed that the Brake valve was weeping oil everytime it was pressed. Changed that and it went away. That also gave a very different feel to the car.
Might be worth just having a look behind the brake pedal at the spring that acts on the valve and see if it's damp, or leaking.
Ste

NiSk · Post by **NiSk** » 09 Jan 2005, 04:52

Oh Yea?
Has the Xantia inherited that bad trait from the BX as well? (leaking doseur valve).
//NiSk

DarkendViper · Post by **DarkendViper** » 09 Jan 2005, 15:17

I was the only one that the local citroen dealer and specialist had known go wrong with it since they came out in 94. I think it was just probably the way my car was driven. Lots of motorway driving with hard braking on the lsip roads.
Ste

DoubleChevron · Post by **DoubleChevron** » 10 Jan 2005, 04:13

Hmm,
I have a Xantia VSX and it's brakes are bloody awful. Crash stops are brilliant as is light braking, however anything in between is hard/impossible to regulate (bloody spring under the pedal I think). I simply can not get over the stupidity of Citroen ... Putting a spring between your foot and the brake valve ... utter stupidity.
The BX has brilliant brakes, the 'brake pedal' feel is even better than my CX GTi Turbo however not as good as the mushroom in my early ID19. It's beyond me why Citroen keeps going backwards instead of forward. They put a dangerous spring between the brake pedal and valve on the Xantia, then COMPLETELY REMOVE the proper high pressure brakes from the C5 ... WTF ??? You have something superior to everyone elses system for 50years, so you decide to not use it anymore because it's 'different' to the inferior product everyone else uses ...
seeya,
Shane L.

David W · Post by **David W** » 11 Jan 2005, 19:36

As everyone says....
Very common and loads of Xantias do it to a greater or lesser extent. My first move is to replace the accumulator sphere if older than a year, then bleed the brakes through (rear is where you will often find gas).
Now this is about as good as it will get without more intensive repairs...and perhaps as good as you need?
Next step might be to replace the main brake valve, some say this gets things near to perfect but its expensive/fiddly. Also consider removing the spring from the brake pedal, but only if 100% sure or a safe result.
This issue was commented on by some testers when the Xantia was launched brand new...and I know at least one chap who sold his as the wife was unable to put up with the braking variation even after all the above repairs were made.
David

MikeO · Post by **MikeO** » 11 Jan 2005, 19:42

Thanks everyone for your input. Car passed its MoT today without a snag. I think I'll leave well enough alone, unless it gets any worse, then maybe go for the accumulator sphere change...
Thanks again,
Mike[:)]

Kowalski · Post by **Kowalski** » 12 Jan 2005, 14:58

I've never had problems with controling the braking on my Xantiae.
At times the brakes have been a bit variable (usually getting more braking than you were expecting) but nothing that I couldn't compensate for by adjusting my foot pressure.

modi · Post by **modi** » 12 Jan 2005, 16:09

How do I bleed the front brakes?? my brakes all also funny, the car react very quickly when I apply them so I always try to be light on them for slowing down!! and also they vibrate sometimes on just normal use (not activiate the ABS) which is strange and scary.. and idea??

Sahand · Post by **Sahand** » 21 Jan 2005, 06:59

Hi all!
i have the same problem with my xantia. also i noticed that the way car treats on brakes depends on my speed. the higher the speed, more and high frequency shakes! however if i am going very very slow and i push the pedal a little it acts as i press the pedal for a short time, then release, then press again - very smooth(!) shaking.
i recently checked discs and notice some part of disc in engaged (with no brakes) a little when i revolve it. i don't know if this little is the making problem or hydraulics. meanwhile my accumulator is ticking, and very high freq. in last week, no ticks this week!! anyway i'm going to change it by weekend.
any ideas on my problem? tnx in advance!

Sahand · Post by **Sahand** » 21 Jan 2005, 07:09

ammm.. forgot to say, when i press brake pedal hardly and quickly, a whipping (fishhhing, or whoooping, duno some loud noise like high pressure water passing a pipe!) sound appears right after i release the pedal. pedal acts like a hard spring in this case! maybe helpful! cheers.