Xantia brakes

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PaulW
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Xantia brakes

Post by PaulW »

Hello, I have a Xantia 1.6i 1994. This is the first Citroen I have owned and don't know anyone else with one, I have a question about the brakes. When I use the brakes they are quite sharp and then tend to fade a little and then bite again repeatedly.... is this normal? also on slight inclines the car won't roll with brakes off. The pads and discs are low but ok (well enough to get through the MOT [:)])
Thanks.
alexx
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Post by alexx »

Well, in my opinion there are very few cars giving so good feel on the brake pedal like citroen hydropneumatic vehicles.
System is so constructed, that:
1. force on the pedal is in direct proportion with braking force, which is very hard to achieve on conventional braking systems
2. brakes react the same moment you press the pedal. It's not the case on conventional systems, where air needs a fraction of second to enter the brake servo unit through a relatively small orifice and it develops full braking force. That's the reason why ordinary drivers, used to that system, always had problems driving Citroens. And that's the reason why they invented Brake assist - to shorten response time of the brakes. Hydraulic brakes are fitted with BAS for decades.
If you Xantia is behaving differently, there must be something wrong. First, try bleeding brakes.
PaulW
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Post by PaulW »

Thanks guys, it seems like driving in the wet you have to be looking 100 yards ahead [:D] also when you change gear with your foot on the brake and the suspension being quite soft it has a "nice" rocking motion [:)]
I did wonder if the brakes needed bleeding as they did feel like they were fading for a second but then would bite again then fade and repeat until stopped.
alexx
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Post by alexx »

Maybe you have flat accumulator sphere. Do you hear clicking from the hydraulic regulator every second or two, and brakes fading and biting accordingly?
Other possibility is air in front or rear brakes, so maybe brakes on one axle grabs first, then after a second or two (when air gets compressed) brakes on other axle. Air in rear brakes will cause noticable rising of rear end when braking, until rear brakes grab. Air in front brakes will cause noticable diving of rear end, until front brakes grab.
PaulW
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Post by PaulW »

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

Maybe you have flat accumulator sphere. Do you hear clicking from the hydraulic regulator every second or two, and brakes fading and biting accordingly?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I get the clicking when the suspension first levels out usually takes about 5-10 seconds to level out then the clicking is irregular nowhere near every second or two.
About 10 seconds after I turn off the engine I get a creaking door sound as the car sinks but not to the bottom of the suspension is that normal?
Sorry about all the questions but Citroens are a bit of a mystery to me never having owned one until now.
alexx
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Post by alexx »

Several clicks until suspension levels out are normal. After that, it should be at least 20-30 sec between clicks.
Anyway, it's possible that pressure in accu sphere is low, and that regulator ticks faster when braking, because some LHM is used for brakes. Try braking several times and listen are there any connection of brake force variation and clicking.
If it turns out that accu sphere is ok and no air in the brake lanes, it may be worn brake dosieur valve (or something else).
Creaking from rear suspension is usually connected with worn rear arm bearings. Check the rear wheels.
If they are slanted //----\\, that's it. Normal angle is only about 1 degree.
Sinking of rear end after STOP light is gone can be connected with low pressure in anti-sink or accumulator sphere. In the case of accu sphere low pressure, after you switch off the engine and unload the car, sometimes it won't sink back to normal height, but after you switch the engine on again. Try this: when you park the car, get out, wait the car to stabilise and then switch the engine off. After leaving the car overnight, switch the engine on. If there's no sinking, it's probably accu sphere. If it sinks, it's probably anti-sink sphere.
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