Xantia Brakes

Mandrake · Post by **Mandrake** » 31 Aug 2005, 03:45

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Jay Farnsworth

Hi again,
After doing some more reading, I also have similar problems to others in another way to the lip. I am also experiencing the squishy, shh, shh sound when I pump the brakes. I guess i will try the full brake bleeding option, although, all the haynes manual (or was it on the andy spares forum) says is to raise and lower the suspension (citrobics) and the system should self bleed through the resivoir. I take it that this is not the complete way of bleeding, any tips before I attempt to look for the bleed nipples? (I have taken note of using a ring spanner and plenty of pre-lub!).
Thanks again Jay

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Citrobics will only bleed the suspension, which is a recirculating system, but not the brakes, as they are a dead end path for the oil. The brakes will only ever bleed by using the bleed nipples.
It's pretty easy to do, my advice is to set the suspension to full height, and only do one wheel at a time - eg jack up that corner (at a suitable jacking point) enough to get the wheel off, bleed that corner while the other wheels are still on the ground (chocked against rolling of course) then put that wheel back on and move to the next one.
As discussed in another recent thread because the rear brakes run from the rear suspension pressure, if you jack up both corners of the rear so both rear wheels hang free you may not have any pressure to activate the brakes..whereas one wheel at a time will always work.
By the way, if you're pumping the brake pedal hard, (pressing it to its full travel, which is more than you would normally ever press it) a "slurp" noise when you release it is perfectly normal.
Regards,
Simon

Mandrake · Post by **Mandrake** » 31 Aug 2005, 04:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Jay Farnsworth

Hi all, ('97 Xantia SX 1.9TD 71K)
I have exactly the same problems you all seem to be mentioning. It didn't start until I changed the discs (and the pads as well), then, as you have all discribed, lots of soft feeling brake, until all of a sudden loads of force and really good braking.
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Hmm, I'm surprised to see that with new discs. Did the problem occur immediately after the new discs were fitted ? EG did they never satisfactorily bed in over the following days/weeks ? Or were they ok for a while then got worse ? If so what mileage ?
Did you replace the discs and pads at the same time ? If you put new discs on, its pretty important to replace the pads at the same time even if they have plenty of thickness, because the pads will have worn to a shape that matches the old disc, and not only will they probably not contact over 100% of the surface area, but they may even help to wear the new disc in the same way that the old one was. (EG same ridges etc)
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I did notice when I got the tires changed that there is a very pronounced lip on the outer edge of the pad and the inner edge of the disc. This got me scratching my head abit as I double, triple, and quadruple check to make sure I got the correct discs and pads, whilst also noting that there is no way of adjusting the caliper to hub assembly to make the pad fit on the disc better.
Is this lip normal of all xantia brakes? Is it likely that this will solve me weird braking problem? Im seriously concerned as Im lending the car to my uncle for a month and I dont want him to be put off all of a sudden and crash (it can be pretty unnerving when it happens at roundabouts braking from 70).
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Again, what mileage after the new discs has this lip become apparent ?
To a certain extent a lip like this on either side of the disc is normal for any disc brake system after the disc has done high mileage, but not after low mileage.
The simple reason is that the pads wear the disc down in the middle but not at the very edges - partly because the pads usually aren't exactly the same width as the disc, (and different brand pads may be slightly different widths too) but also because even if the pad and disc were the same width, because the pad material is not a hard solid material (it can flex slightly) full pressure is not applied to the very edges of the pad, as they tend to squish sideways slightly, hence less disc wear at the edge.
If you can see a lip or contact mark on the edge of the pad, try taking the pads out one at a time (don't mix them up, now that they have bedded in) and chamfer the edge down a bit with a rasp or large file. Don't take too much off, 1-2mm with a 45 degree chamfer. Probably a good idea to do all 4 edges.
If you do try it, let us know the result.
Regards,
Simon

Jay Farnsworth · Post by **Jay Farnsworth** » 31 Aug 2005, 04:11

Thanks Simon, that makes it all make sense! I though Citrobics alone was too easy, LOL.
I have been reading abit more in the forums, it definately seems like I need to do a bleed, it all seems resonable considering I changed the spheres. I think that one of main issues we have here is that haynes did a rubbish job on the xantia, it is all very ambiguous, they could have been much clearer (or it might be just me), not just on the brakes front but the book is pretty bad on the important details of fittings and electrical. Dont get me wrong, I really appriciate haynes and I know they have a hard job, but boy do I wish that they read this forum and updated their book.
Anyway here is not the place to complain (I will find a different thread for that). I m glad you said that the slurp is normal, and I will take the advice on the bleeding one wheel at a time, I am a outside the house on the road kinda mechanic (eek sometimes), tips like that are always useful.
Think I will have a go at trying the bleeding direct into the resivoir route, sounds fun, but I have to ask, does the engine need to be running for all this?
And all this aside is the brake edge lip thing caused anyone any probs, how big can it get before worrying, mine is pretty visable!
Jay

Mandrake · Post by **Mandrake** » 31 Aug 2005, 04:17

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jeremy

Strangely enough a flat accumulator sphere will make the warning light go out very quickly but I agree a weak one will take longer to charge due to the greater volume of LHM required.
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Nothing strange about this - a punctured sphere has no gas at all, thus nothing to expel the oil as the pressure drops, so it sits full of oil in all conditions, therefore no oil needs pumping back into it for the pressure to rise again.
On the other hand a sphere with a small amount of gas can still expel all the oil from the sphere as the pressure drops...
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You could try testing the accumulator by getting the car to normal height and letting it run for a couple of minutes, turn off the engine and sit in the boot. The car should sink and after 30 seconds rise again. It may even do it twice if you are lucky. If it just sinks the accumulator is flat. I think this works on an Activa - but I'm sure Simon will correct me if I'm wrong.
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Alas, I've never seen an Activa in the flesh, so can't comment on this. [V] Over here they're very rare (I've been told there are only 15 in New Zealand) and rather expensive. (About 2 1/2 times what I paid for my 2.0 VSX Auto) Add to that the fact that nobody that owns one wants to part with it, my chances of ever getting one are close to zero unless I import one...[:(]
On my HA2 Xantia I notice that even though I have a new accumulator, when the suspension is in the soft mode it can only just barely lift me once at the back, but in hard mode (key off and all doors/boot closed) the back will lift me about 3 times. I guess in soft mode due to an extra sphere there is more oil required to make the correction...
Regards,
Simon

Mandrake · Post by **Mandrake** » 31 Aug 2005, 04:25

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Jay Farnsworth

Thanks Simon, that makes it all make sense! I though Citrobics alone was too easy, LOL.
I have been reading abit more in the forums, it definately seems like I need to do a bleed, it all seems resonable considering I changed the spheres. I think that one of main issues we have here is that haynes did a rubbish job on the xantia, it is all very ambiguous, they could have been much clearer (or it might be just me), not just on the brakes front but the book is pretty bad on the important details of fittings and electrical. Dont get me wrong, I really appriciate haynes and I know they have a hard job, but boy do I wish that they read this forum and updated their book.
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You're not alone, the Haynes book for the Xantia is just rubbish. Unfortunately its all I have too, apart from some of the stuff that can be found on the net.
Not only is it ambigious and confusing (for example engine overhaul procedures for completely different engines are all interweaved) but there is some outright false and incorrect information and advice. (Which is why some people on the forum here semi-jokingly refer to it as the BOL - Book Of Lies [:D])
It's a shame, because genuine Citroen service manuals are top notch but they seem to be nearly impossible to get hold of these days. (Back when I had a GS I had the genuine service manuals for it, and they were some of the best I've ever seen for any car)
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Anyway here is not the place to complain (I will find a different thread for that). I m glad you said that the slurp is normal, and I will take the advice on the bleeding one wheel at a time, I am a outside the house on the road kinda mechanic (eek sometimes), tips like that are always useful.
Think I will have a go at trying the bleeding direct into the resivoir route, sounds fun, but I have to ask, does the engine need to be running for all this?
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Yes, if you're going to do a continous recirculation back to the tank the engine should be running.
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And all this aside is the brake edge lip thing caused anyone any probs, how big can it get before worrying, mine is pretty visable!
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Well the lip on the edge of mine is nearly 1mm (eg 1mm of wear on the main swept area) but provided that the swept area is flat and the pads have a small chamfer on the edges to stop them touching the lip, it shouldn't matter. The real culprit seems to be non-flatness of the swept area.
Regards,
Simon

Jay Farnsworth · Post by **Jay Farnsworth** » 31 Aug 2005, 04:44

Again, thanks Simon.
I think that solves my issues for now, I will go and do a brake bleed and come here rather than the BOL in future

I m just glad its not just me being nieve, and that I have also found that someone else has experienced what I thought to be wrongness!
The lip is about 3mm on the front pads, i do get a bit of high pitched squeal when I turn full lock and really low speed, its not disc surface to pad squeal, it is definately a grinding between the top of the disc and the pad lip! I guess a bit of gentle file use will help here!
Anyway, thankyou again, simon you are a great help! Will post and let it be known how it goes!

Jay

lawns · Post by **lawns** » 10 Oct 2005, 16:38

Have you looked at your abs sensors. I had a similar problem after replacing a drive shaft gaitor and not refitted the sensor correctly.
Lawns2 thread on ABS refers.