Terrible Xantia brakes

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zzf00l
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Post by zzf00l »

Methinks that Thunderbird is on a 'wind up' and has generated the response he was after!!! :-)
paranoid
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Post by paranoid »

NAHHHH T/Bird has always had issues with his brakes.
Fair play really If you aint happy etc......
Thunderbird

Post by Thunderbird »

Yes, that's right - I've always complained about my Xantia HDi brakes.
It's one of the few things I dislike in this superb machine. When something unexpected appears on the road, I would like to stop in shorter distances. My previous Citroen did it, so have a few other cars I've tried, like the Renault Laguna. I've also admited most cars brake as badly as the Xantia, but you must compare it with the best at its price range.
Aspects that I believe will improve Xantia braking:
- Assisted emergency braking (like found in most recent cars).
- Tyres with more grip (unfortunately the best tyres don't have my Xantia wheels specification, 205/60 R15).
- More intelligent ABS computer. This makes a big difference.
- Bigger disks.
- More efficient cooling.
- Faster acting and more stable suspension.
Yes, I know what you're thinking - it will be cheaper to buy a new car... [:D]
macaroni
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Post by macaroni »

While you're at it, why not add Ceramic Disks to the list?
Nomad
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Post by Nomad »

Hi all
OK after following this thread since the start of it, i decided to give it a go on my Xantia, not that i have many complaints about the breaks on it, although i have felt from time to time that i have miss judged the pressure needed to stop the car where i wanted.
Now maybe i have completely got the wrong idea on this, but where is the spring you are all talking about. i have looked under my break pedal and all i see is a rod that is bolted onto the pedal arm it's self disappearing into the bulkhead, i have tried to get my hands further up the pedal but they are to big. I have removed the little bit of carpet that hides the pedal boxes, but all i can see is this rod.
The rod is approx 8mm in diameter and i would guess flattened at the pedal end, then a 8mm nut and bolt fixes it to the pedal.
My Xantia is a 95 1.8i hatch back.
Thanks
Tony
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davek-uk
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Post by davek-uk »

Tony, the black plastic contraption that Shane pictured (http://www.aussiefrogs.com/shane/xantia ... gunit1.jpg) is a few inches above the 'carpet' pedal covering. You can feel it by putting your hand up behind the brake pedal.
The large diameter (left hand in the pic) part pushes into the pedal from behind and locates there - it is a tight, wriggle fit. The spring is inside the thinner section. The large diameter collar slides down to reveal the split retainer washer that keeps the two halves from separating. Take this off and the thinner section pulls out - inside you have a spring and a centre core of rubber.
Incidentally, my spring (on a 97 model) is pretty strong. Even so I'm going to try a rod replacement and see how it performs.
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Post by Nomad »

Hi and thanks for the reply
I have put my hand up as far as it can go, and i can not feel this black plastic contraption there.
The rod i am talking about is the only thing i can see or feel there. When i move on the pedal in & out the rod moves in & out, which as far as can see is what opperates the breaks.
Here are 2 pics of the pedal arm and the rod
The pedal arm is made from flat bar about 6mm thick
Image
Image
My car is a left hand drive made for Germany, so maybe it is different, and does not have this black plastic contraption.
Cheers
Tony
Rostami
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Post by Rostami »

Quote:
"My car is a left hand drive made for Germany"
Are the Xantias made for Germany different than other LHDs?
samtronic
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Post by samtronic »

It seems not all Xantias have a spring fitted.
These are pictures from my ´93 1.8i (Danish LHD):
Image
Image
Søren
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Post by Nomad »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Rostami</i>

Quote:
"My car is a left hand drive made for Germany"
Are the Xantias made for Germany different than other LHDs?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
That i have no idea about, it was just a suggestion, as at the time i seemed to be the only one here without this spring on the pedal.
[?]
Tony
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Post by pete_wood_uk »

I've just done this mod to both my Xantias (Xantiae?) at the weekend, so thought I'd add a testimonial: Wow!
If you have a Xantia with a spring (which appears from this thread to mean an RHD one), then go do this, honest! Takes 10 minutes and a short length of 15mm copper water pipe. You won't regret it.
I'd never been too worried about the brakes on my '97 TD, for sure they weren't CX brakes but they weren't bad. But having just done my first extended driving on roads with hills in the '00 HDI (driving holiday round Scotland, normally it's my wife's car and we live in the Cambridgeshire fens) I came to the conclusion that the HDI brakes were bloody awful. Unprogressive, lacking in bite, etc. Occasionally just plain scary.
So I swapped both springs out, and fitted water pipe instead. Interestingly, in view of what's been said here, I found both springs to be identical, despite the very different feeling of the cars' brakes. Both cars are improved; the '97 TD brakes are now superb, just what Citroen brakes should be; the '00 HDI is much improved, the bite is back, as is the progressiveness once the brakes are fully engaged, but I'm still not happy about the first light-touch performance.
The HDI brakes seem too sensitive to a light touch, then you can almost feel the hydraulics kick back at you. Last time I saw a cut-away diagram of a Citroen brake valve, I seem to remember that there's a spring at the back of it, presumably to keep it shut, so you have to push against that spring to keep it open. It's almost as if that spring is a bit too light - does anyone know if its spec changed over the years...? Or can I wind some preload on it? :-).
Readers should take some of this with a pinch of salt - I've only had the HDI for 8 months, so I have no idea what front pads it's currently got in it, and also it's got a bit of a warp on one front disc, which isn't helping matters. The pads are over half-worn, so when they finally go it's due for new discs and pads, which may help it a bit.
Cheers
Pete
PS: Shane, you've got much stronger hands than I have - I spend my life driving a keyboard or (at worst) a soldering iron, and I can't compress the springy thing like you can.... :-(.
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Mandrake
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by pete_wood_uk</i>
So I swapped both springs out, and fitted water pipe instead. Interestingly, in view of what's been said here, I found both springs to be identical, despite the very different feeling of the cars' brakes. Both cars are improved; the '97 TD brakes are now superb, just what Citroen brakes should be; the '00 HDI is much improved, the bite is back, as is the progressiveness once the brakes are fully engaged, but I'm still not happy about the first light-touch performance.
The HDI brakes seem too sensitive to a light touch, then you can almost feel the hydraulics kick back at you.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
One thought here - is the accumulator sphere in good condition ? (Try the sitting in the boot test mentioned recently in the forum) A poor accumulator sphere could cause symptoms similar to this - without much (or any) gas in the sphere when you press the pedal initially the supply pressure will drop and you won't get as much braking as you should, then as you press a bit harder, it will drop enough so that the regulator cuts back in, and because there is little or no compressible medium in the sphere, the pump will cause the pressure to suddenly jump up in big lurches.
Because the brake valve uses the brake pressure as the main source of feedback (see below) you'll actually feel this on the pedal.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
Last time I saw a cut-away diagram of a Citroen brake valve, I seem to remember that there's a spring at the back of it, presumably to keep it shut, so you have to push against that spring to keep it open. It's almost as if that spring is a bit too light - does anyone know if its spec changed over the years...? Or can I wind some preload on it? :-).
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
As far as I know (and I don't claim to be an expert on this, so I could be wrong) the spring is quite soft, and is only there to ensure the valve will close fully when the pedal is released.
When normal system pressure is available, the pressure on the output side of the valve going to the front brakes is also piped to the piston formed by the end of the control shaft, and this is the dominant reaction force you feel - in effect you're pressing against a scaled down version of the pressure going to the brakes, so the pressure your foot is pressing on the pedal is DIRECTLY proportional to the brake pressure. This is what gives Citroen brakes their extremely precise proportional control.
So unlike a normal brake valve, you pressing the pedal opens a valve to the high pressure supply rather than pushing the oil directly, but the oil also pushes back at you to form an equilibrium.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
Readers should take some of this with a pinch of salt - I've only had the HDI for 8 months, so I have no idea what front pads it's currently got in it, and also it's got a bit of a warp on one front disc, which isn't helping matters. The pads are over half-worn, so when they finally go it's due for new discs and pads, which may help it a bit.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Indeed, it could be very ordinary things like pads etc... often people use front pads that are too hard - they last long but they don't give a good bite action...
Perhaps the calipers could do with lubricating too...in any case, now that they both don't have springs, unless the accumulator sphere is a bit stuffed on the HDi, any differences in the brakes are likely to be discs/pads/calipers etc, as the brake valves should be identical.
Regards,
Simon
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Post by Chrispy »

I did the brake mod on Saturday and must admit it has cured most of the wavy braking action. I can now predict how hard to press the pedal. Admittedly I haven't been down a motorway slip road since but will tonight so we'll see. I too am having accumulator/ regulator problems so we'll see if the wavyness is still there.
I can imagine though that the pressure surge from the pump will be immediatly felt and then when it lets go again resulting in a wierd fluctuating braking feel.
Just out of curiosity, how long do you have to sit in the boot for to test the acc sphere? Is it 30 seconds or longer? Trouble is, without me checking to see if the ball bearings are still there I can't tell whether it's my new sphere at fault or my regulator. Worst comes to the worst the regulator can be replaced but there's 2 on GSF....one at £92 and one at £130. Dunno which would be the one....
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CitroJim
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Post by CitroJim »

Did the mod on mine today. Thanks Pete Wood for the tip about using water pipe. Works a treat!
It has certainly made a difference to the feel of the brakes and well worth the ten minutes it took to do...
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Mandrake
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Chrispy</i>
Just out of curiosity, how long do you have to sit in the boot for to test the acc sphere? Is it 30 seconds or longer?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
It should start to lift you in about 5-10 seconds, certainly no longer than 30 seconds. If the accumulator is in good condition, it won't be much slower to lift you (the first time) than when the engine was running.
Regards,
Simon
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