406 brakes too sharp

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jmason
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406 brakes too sharp

Post by jmason » 19 Sep 2003, 04:18

Hi all
The brakes on my 406 estate are too sharp. It only takes the least pressure to have the front of the car nosediving. (and this is not me being lead-footed!). It's a pain when you are trying to drive smoothly with the car pitching all the time. They have been like this since i got the car 3.5 years ago so it it is not a new problem. I'm just fed up with it as it mars the otherwise excellent handling of the car.
The only other (minor) brake issue is that the very first time that i brake in the morning - there is no stopping power in the brakes at all. I have to make sure that i brake after pulling away to kind of "prime" them. after that work fine (except for being too severe)
Any ideas as to what this could be causing these problems??
thanks
john

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benj
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Post by benj » 19 Sep 2003, 11:31

theres a 406 in my family with the same problem, if anyone could help it would be great

alan s
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Post by alan s » 19 Sep 2003, 15:00

An age old problem with Citroens that drive a lot with light loads particularly around town is the rear wheel cylinders seizing due to lack of use. These will tend to get a bit divey at the front when this happens but as they also have a fairly involved & sophisticated hydraulic system, it isn't as harsh as you guys have described, however, I'm still inclined to think that going on the symptoms, that's where your problem is coming from.
We usually remove the rear wheel pistons, clean & free them up & refit and then take it for a "brakes on/brakes off forward & reverse" drive to be sure they all adjust up even.
The fact that the brakes are a bit sluggish at first start up also points to this possibly being even slightly in the front also, so it may be a good idea to do all 4, renew your brake fluid at the same time & give them a good bleeding to get all the old stuff out of the system particularly out of the wheel cylinders as it tends to get very contaminated in the cylinders.
Alan S

Ben83
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Post by Ben83 » 19 Sep 2003, 15:28

> An age old problem with Citroens that drive a lot with light loads
> particularly around town is the rear wheel cylinders seizing due to
> lack of use.
wouldn't seized rear cylinders make the car an mot failure? If it's had the symptoms for 3.5 years, it must've been moted even if John bought it from new.
I'm afraid I can't offer an alternative suggestion though, sorry.
Cheers,
Ben.
1995 306 1.4.

alan s
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Post by alan s » 19 Sep 2003, 16:10

I don't know how they do the tests but if it's a "jab" chances are it would pass the test. As I say, it's a problem so common with Cits that we take it as a part of life. Silly part is, that with a Citroen, they stop so well even when they are seized it is almost impossible to detect for anyone driving the car constantly and one of those things that only when rectified does the driver then comment on how much it's improved.
Alan S

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benj
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Post by benj » 19 Sep 2003, 17:37

when doing an mot its just the font wheels they have on the rollers isnt it? then they check the handbrake which is cable operated
If my symptoms are the same as jmason i dont think its the rear brakes which are at fault, the rear breaks hardly do anything anyway,
its hard to describe but the brakess just bite really sharp, the resultant nose dive is because the brakes are so sharp not because there isnt enuf power in the rear, i tend to think its some type of regulating valve, hence on startup no brakes, as if some regulating system has broken and then is bypassed.

wheeler
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Post by wheeler » 19 Sep 2003, 18:04

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

when doing an mot its just the font wheels they have on the rollers isnt it? then they check the handbrake which is cable operated
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">the footbrake performance is checked on all 4 wheels as well as the handbrake.

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benj
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Post by benj » 19 Sep 2003, 18:11

well im sure thats how its supposed to be done, now in practise tho....

alan s
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Post by alan s » 19 Sep 2003, 18:34

We'll try another tack then.
Do they have a split master cylinder like a lot of the Jap cars?
If so, I'd be looking at that as a starting point; all power hitting the front first (as it is supposed to) but then as pressure is applied, the power keeps increasing to the front wheels and is getting more than it should. In other words, instead of the power distribution being say 60% front 40% rear, you could have a 70/30 situation. Brake systems HAVE to work in such a manner that the front brakes work prior to rear & brake bias is normally set favouring the front so we have to be looking at an uneven distribution of stopping power and this could start at the master cylinder or air in the rear circuit as being the starting points.
I'm still inclined to feel that it may be almost necessary to do a fluid change or at least a brake bleed so as to be able to troubleshoot it.
Some of the Jap cars had a valve on the centre of the rear axle to reduce pressure to the rear brakes and this worked on the basic principle of moving a lever that controlled a valve in the rear brake line circuit which was activated by axle wind up. When the axle started to twist due to wheel lock up, the fluid was partially released to take the pressure off the rear brakes. If the master cylinder is OK and the brakes bled, then I'd be looking for something like this if it is on this model.
Be nice if someone au fait with Peugeots could give an opinion or at least advise if something like this is fitted, where it is located & how it looks.
Alan S