Brake discs and pads

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Badge 714
Posts: 11
Joined: 29 Feb 2012, 09:42
Location:
My Cars:

Re: Brake discs and pads

Post by Badge 714 »

All sorted thanks guys. A lot easier to wind in the piston with the hose clamped and the bleed opened thanks Estately. Lightly is bang on, Anti clockwise on the drivers side and clockwise on the passenger side and HDI's tip of using a 3/8 ratchet was also really helpul. I used the ratchet to turn it a couple of times then a clamp to squeeze the fluid out to get started then it was pretty easy, took quite a few turns on mine. Bled both sides after reassembly.
garrydog
Posts: 62
Joined: 06 Jun 2011, 18:34
Location: Nr Manchester UK
My Cars:

Re: Brake discs and pads

Post by garrydog »

Can someone tell me why this system is used , why do the pistons have to be wound back ,is it a kind of an adjuster or is it something to do with the hand brake?
A short explanation please .
Thanks .
2004 C5 VTR 2.0L HDI hatchback.
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Post by addo »

The pistons are "threaded" so regular (firm) use of your handbrake adjusts the pads nice and close. This takes up any wearing of the friction material.
HDI
Posts: 1468
Joined: 22 Sep 2009, 15:46
Location: West Mids
My Cars:
x 7

Re: Brake discs and pads

Post by HDI »

Personally I've always thought that a handbrake operating on the front brakes is not good engineering. Clamping the brake pads to a hot disc when parking must cook them and could also cause the handbrake to slacken when they cool. I have to say I haven't noticed that in practice but I don't use the handbrake when parking on the level, I just leave it in gear.
Now using '00 Xantia LX HDI, pov spec :(
My past Citroens :-
'00 Xantia SX HDI, now dead due to accident :(
'99 Xantia HDI 110 Exclusive, RIP :(
'97 Xantia TD SX
'96 Xantia TD LX
'96 ZX TD
'89 BX TD
'88 AX GT
'79 CX2400 Pallas (scrapped :( )
& a couple of Peugeots !
User avatar
Clogzz
Posts: 2115
Joined: 15 May 2005, 18:04
Location: Australia
My Cars:
x 36
Contact:

Re: Brake discs and pads

Post by Clogzz »

Citroen says that under no circumstances should the car be parked with only the handbrake applied.
There have been cases of BXs and Xantias rolling away when the brakes were cooling.
2002 C5 2.0i AL4 230,000 km 76372389
HDI
Posts: 1468
Joined: 22 Sep 2009, 15:46
Location: West Mids
My Cars:
x 7

Re: Brake discs and pads

Post by HDI »

Ah ha !! Thanks for that. Must have a read of the manual on that topic.
Now using '00 Xantia LX HDI, pov spec :(
My past Citroens :-
'00 Xantia SX HDI, now dead due to accident :(
'99 Xantia HDI 110 Exclusive, RIP :(
'97 Xantia TD SX
'96 Xantia TD LX
'96 ZX TD
'89 BX TD
'88 AX GT
'79 CX2400 Pallas (scrapped :( )
& a couple of Peugeots !
User avatar
Lighty
Posts: 1103
Joined: 07 Jan 2012, 16:53
Location: Derbyshire
My Cars:
x 34
Contact:

Re: Brake discs and pads

Post by Lighty »

Glad you got it sorted :mrgreen:
Having the handbrake on the front wheels is a truly stupid idea, no idea why they do it, the cables take some grief having to bend so much all the time as well.
This running away thing is a big problem, and I believe it is why manufacturers now fit electric systems, as they constantly monitor the wheel sensors, and any movement causes the car to pull the brake on a bit more when you are not even with the car. One hell of a hammer to crack a nut idea imo, but I guess a couple of public liability claims against the manufacturer makes it a necessity.
I cant see any other advantage to an expensive electric system.
http://www.marklightfootltd.co.uk
Dacia Duster 1.5 dci
Renault Twizy Technic
Citroen C15
Citroen Ami
HDI
Posts: 1468
Joined: 22 Sep 2009, 15:46
Location: West Mids
My Cars:
x 7

Re: Brake discs and pads

Post by HDI »

The most likely reason for using that method is it is cheap !
The best compromise is a small separate drum brake within the rear disc, a method used by Mitsubishi and Mercedes to name 2.
Now using '00 Xantia LX HDI, pov spec :(
My past Citroens :-
'00 Xantia SX HDI, now dead due to accident :(
'99 Xantia HDI 110 Exclusive, RIP :(
'97 Xantia TD SX
'96 Xantia TD LX
'96 ZX TD
'89 BX TD
'88 AX GT
'79 CX2400 Pallas (scrapped :( )
& a couple of Peugeots !
User avatar
myglaren
Forum Admin Team
Posts: 25366
Joined: 02 Mar 2008, 13:30
Location: Washington
My Cars: Mazda 6
Ooops.
Previously:
2009 Honda Civic :(
C5, C5, Xantia, BX, GS, Visa.
R4, R11TXE, R14, R30TX
x 4888

Re: Brake discs and pads

Post by myglaren »

I forget why but someone did explain that the handbrake on the front was to do with the hydraulic self-leveling.
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Re: Brake discs and pads

Post by addo »

HDI wrote:The best compromise is a small separate drum brake within the rear disc, a method used by Mitsubishi and Mercedes to name 2.
And the Peugeot 605. :mrgreen:
myglaren wrote:I forget why but someone did explain that the handbrake on the front was to do with the hydraulic self-leveling.
I'm not 100% convinced by this explanation. Other trailing arm cars have had successful handbrakes on the rear - R16 and R19 for example. More I suspect it was to induce controllable understeer when the handbrake is applied in an utter emergency.
User avatar
myglaren
Forum Admin Team
Posts: 25366
Joined: 02 Mar 2008, 13:30
Location: Washington
My Cars: Mazda 6
Ooops.
Previously:
2009 Honda Civic :(
C5, C5, Xantia, BX, GS, Visa.
R4, R11TXE, R14, R30TX
x 4888

Re: Brake discs and pads

Post by myglaren »

addo wrote:I'm not 100% convinced by this explanation. Other trailing arm cars have had successful handbrakes on the rear - R16 and R19 for example. More I suspect it was to induce controllable understeer when the handbrake is applied in an utter emergency.
I'm guessing but I think it has to do with the wheels rotating and moving forward or back when the car sinks/rises and this motion being impeded by a rear handbrake.
Probably more of an issue with earlier cars that were sinkers from the start.
addo
Sara Watson's Stalker
Posts: 7098
Joined: 19 Aug 2008, 12:38
Location: NEW South Wales, Australia. I'll show you "Far, far away" ;-)
My Cars: Peugeot 605
Citroën Berlingo
Alfa 147
x 93

Re: Brake discs and pads

Post by addo »

From an engineering POV, that still doesn't cut it. It really sounds like a backformation by someone who is either being a selective triumphalist (aka cheerleader) or hasn't seen enough other designs.

Renault dealt with the problem by having the rear brake cables placed in such a manner that ride height left no change to the tension upon them. Lost motion in any driveline will take up the small amount of wheel rotation as height changes.

Citroën were aware that the Dee was nose-heavy, massively so. I really think they were trying to maximise controllability (makes sense in terms of how much it was engineered to address worst-case scenarios) and part of this was ensuring an emergency application of the handbrake didn't result in wild tailslides.
Post Reply