Rear Brakes on 1991 BX

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alpha1

Rear Brakes on 1991 BX

Post by alpha1 » Sat Jul 29, 2006 4:03 pm

Just failed MoT on rear brakes,rolling road showed zero on both sides have checked pads,pistons in callipers are all free and not seized,have tried bleeding but no fluid is appearing anywear even with bleed screews removed.
Front accumilator sphere has been replaced, most of the front to rear pipes renewed.

Any advice would be most helpful to put right

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ken newbold
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Post by ken newbold » Sat Jul 29, 2006 4:15 pm

You need to bleed the rears with the pressure on the suspension.

alpha1

Post by alpha1 » Sat Jul 29, 2006 4:28 pm

Have tried bleeding with front on ground rear arms on axle stands suspension in highest position with engine running is this correct?still no fluid anywhere
sorry for sounding a bit thick but just dont understand citroens.

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ken newbold
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Post by ken newbold » Sat Jul 29, 2006 6:06 pm

I usually place on axle stands and then lift the rear arms up with small jack. (car on normal height)

alpha1

Post by alpha1 » Sat Jul 29, 2006 6:30 pm

Thanks will give it a go tomorrow.

jeremy
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Post by jeremy » Sat Jul 29, 2006 7:28 pm

Remember full height will mean considerable pressure in the rear brake circuit which could be useful.

Does the back drop when the car is left? If the rear arm bearings have siezed it could cause preblems - otherwise think of sending it in for retest with a full tank and a load in the boot to increase the pressure available.

alpha1

Post by alpha1 » Sat Jul 29, 2006 7:55 pm

Thanks for reply

Yes the back end drops when engine turned of,have put some weight in boot but made no difference,as mentioned in earlier post not a drop of fluid at rear calipers,

RichardW
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Post by RichardW » Sun Jul 30, 2006 9:42 am

The rear brakes are fed off the rear suspension. So you've got pressure here as it comes up. Which points to the fault lying either in the brake valve, or in one of the pipes. I think your next move it going to have to be to figure out which pipe is which is which at the brake doseur valve, then see if you get pressure at the rear brake outlet, if so this points to a pipe problem brake valve - rear brakes; if no then check the rear brakes inlet - no pressure = fault with pipe rear-brake valve, pressure here indicates fault with brake valve. Assuming you haven't scraped the bottom on the road, or had the rear subframe out, my money is on the doseur. Trouble is, getting to it on a RHD TD is going to be 'interesting'....
I NEED a BX TD.

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AndersDK
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Post by AndersDK » Sun Jul 30, 2006 11:09 am

If most of the piping front to rear have been replaced - then there is a good chance the 2 pipes at brake doseur valve for the rear brakes have been swapped.

That would fit exactly the symptoms you have with the rear brakes.

On RHD cars the brake doseur valve is a nuisance to access - especially for working on the pipes.
Instead try identify the 2 pipes in question at rear :

1) The rear brakes feed pipe from the brake doseur valve to rear brakes cylinders :
This is one front to rear pipe that connects to a 3-joiner, the 2 other pipes connected to the 3-joiner being the coiled ones to each side's brake calipers.

2) The rear brakes pressure feed pipe. From rear suspension to brake doseur valve. This pipe is connected to a 4-joiner, where one other pipe is connected to the Height Corrector (HC) - and the 2 other pipes on the 4-joiner are connected to each side's suspension cylinders.

(The 2 remaining front to rear pipes are connected to the HC)

Now you have identified the 2 pipes for the rear brakes circuit. Then try/judge if it is possible to swap these pipe connections at rear.
If is not possible - your only solution is to remove the brake doseur valve to work on the pipes and swap the 2 pipes there.
C U / Anders - '90red16riBreak - '91GrisDolment16meteor - Project'88red19trsBreak
dead cars : '89white 16RS - '89antrasitTRDturboEst - '90white19triBreak

AlanS
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Post by AlanS » Sun Jul 30, 2006 11:27 am

Far be it for me to sound patronising, but you do have the engine running when you are doing the brake bleed don't you?????

Alan S
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alpha1

Post by alpha1 » Sun Jul 30, 2006 3:38 pm

Sage continues,

Thanks for all this help guys but still struggling.

1) The rear brakes feed pipe from the brake doseur valve to rear brakes cylinders :
This is one front to rear pipe that connects to a 3-joiner, the 2 other pipes connected to the 3-joiner being the coiled ones to each side's brake calipers.

Have disconnected this front to rear pipe at the front by the crossmember got no fluid here at all even with car running nothing,brake pedal is still firm,
Help I know I,m a pain in the a----

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AndersDK
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Post by AndersDK » Sun Jul 30, 2006 3:56 pm

Ahhhh -

This pipe is supposed to be suppliED with pressure - as it leads to the rear brakes - right ?. You must then fullfill 3 conditions :

1) engine running to supply system pressure for the hydraulics in general.
2) rear suspension loaded to supply rear brakes pressure feed. Best done with rear on wheels (using ramps or wooden blocks) and height set to highest.
3) brake pedal depressed (!) (using a piece of wood clamped between pedal and front seat)

ALL of these 3 conditions must be fullfilled to get rear barkes pressure.
C U / Anders - '90red16riBreak - '91GrisDolment16meteor - Project'88red19trsBreak
dead cars : '89white 16RS - '89antrasitTRDturboEst - '90white19triBreak