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Xantia rear brakes

Posted: 05 Feb 2012, 08:55
by imperial21
Hi Everyone
A problem i have noticed on my car is that the rear pads are only using about 1/2 the disk , anyone know what s wrong ?? I am going to replace the discs and pads anything else i will need to do ???
Thanks

Re: Xantia rear brakes

Posted: 05 Feb 2012, 09:19
by citroenxm
hi.. yes that sounds like the very common "caliper corrosion attack syndrome"

when you get yur wheel off look at the caliper and you may find it sitting at an angle towards the front bacause alloy corrosion has taken hold between it and the arm...

be extreamilly carefull removing the caliper bolts.. do them a bit at a time.. get the caliper off remove the corrosion by tapping it off apply grease or simmilar.. fit new disks and pads job done then have the car on high suspension and bleed the air out (one man job too with the help of a bar) you may notice the pad wear at an angle...

Re: Xantia rear brakes

Posted: 05 Feb 2012, 09:39
by Lighty
Spot on, wait till you try doing a C5 [-o<

Re: Xantia rear brakes

Posted: 05 Feb 2012, 09:46
by citroenxm
i have.. i nearly added above that this problem continues onto c5s but on them the caliper actually damxeages the disk!!! and the disks are bigger and much more bloody expensive too!!!

Re: Xantia rear brakes

Posted: 05 Feb 2012, 10:02
by CitroJim
As Paul says, it's a job you need to attack with great care. Wire brush the exposed thread ends where they poke through the trailing arm and soak thoroughly in Plus Gas and wait...

Before even trying to remove the bolts, remove the pads and replace the small 8mm pad retaining bolt. This bolt will keep the two halves of the caliper tightly clamped together when you come to remove it. Otherwise they'll fall apart and possibly the O ring between them will be damaged or lost.

Then gently go at the bolts with a long breaker bar using very gentle but steady pressure on the end until you feel a bit of movement. Then stop and go back the other way. Keep on to and froing on the bolt until the movement gets bigger. Don't try to rush it. Take your time and go in baby-steps.

The risk of shearing the high tensile bolts is always there. It may seem counter-intuitive to use a big breaker bar on them but it really does help so long as the pressure is steady and gentle. Trying to yank them loose using a short bar is almost guaranteed to shear them and they you really are in a world of pain.

Have some new bolts on hand and then you know the old ones will come out OK! Part No. 96 172 064.

This was the sate of Rattiva's:

Image

Once the caliper is off, you'll find a build-up of aluminum oxide both on the caliper and the trailing arm:

Image

Image

It's hard and will need cold-chiselling and then scraping off!!!

Grease the faces very well when reassembling.

You may find the disc itself is beyond re-use. This was Rattiva's and had to be replaced as the rust was far too well established to clean up:

Image

The C5 is a 'mare I believe as they use Loctite over the whole length of the bolt. Some say heating the caliper with a blowtorch helps soften it...

Please go very carefully with the job as a sheared bolt cannot be drilled. Your only hope is to MIG a nut on what's left and try to extract it that way...

With care it can be done...

Re: Xantia rear brakes

Posted: 05 Feb 2012, 10:43
by imperial21
Thanks everyone for the replys, Jims thats great for the pics i am quite nervious to do the job because if anyone will break it, I will !!!
My discs look like jims, I am keen to do the job asap as i will be towing my caravan soon !!!!

Re: Xantia rear brakes

Posted: 05 Feb 2012, 10:50
by Xaccers
Buy a set of replacement bolts and that should stop yours breaking according to Murphy's law :)

Re: Xantia rear brakes

Posted: 05 Feb 2012, 10:55
by citroenxm
you will feel a massive difference when the rear brakes are working.. the rear end on the black td xantia i had kept lifting right up when breaking.. then when i fitted pads and disks and sorted the calipers she didnt lift and the brakes were stronger too

Re: Xantia rear brakes

Posted: 05 Feb 2012, 10:59
by Lighty
I would suggest a close inspection of the rear brake pipes before you start, as these are sometimes quite corroded, and may snap if disturbed .
It is far easier to source spares before the event than after.

Re: Xantia rear brakes

Posted: 05 Feb 2012, 11:02
by CitroJim
imperial21 wrote:i am quite nervious to do the job because if anyone will break it, I will !!!
Just go easy and gentle and you'll be fine. Give yourself plenty of time to do the job and don't try to hurry the bolts out. Soak the ends really well in Plus Gas and get some Plus Gas sprayed around the edge of the caliper where it touches the trailing arm in the vicinity of the bolts. The oxide is porus and will allow the Plus Gas to soak in and do some useful work.

Use only Plus Gas. WD40 is useless for heavyweight jobs like this.

And as Xac says, avoid Murphy's law by getting a set of new bolts... Note that hatch and Estate bolts are different. The Part No. I've quoted is for the Hatch...

Re: Xantia rear brakes

Posted: 05 Mar 2012, 20:35
by imperial21
I am finally getting close to doing the job, I wondered what people thought of me using a wire brush attacment on the angle grinder to clean the mounting & brake caliper ?

Re: Xantia rear brakes

Posted: 05 Mar 2012, 20:38
by CitroJim
imperial21 wrote:I am finally getting close to doing the job, I wondered what people thought of me using a wire brush attacment on the angle grinder to clean the mounting & brake caliper ?
Won't work. Tried it on a caliper using a bench grinder with a wire brush on it. The oxidisation is so hard the brush doesn't touch it.

A sharp cold chisel is the very, very best tool for the job.

Re: Xantia rear brakes

Posted: 05 Mar 2012, 20:42
by imperial21
DAM !!! I was hoping for a quicker way ! I considered an angle grinder with a grinding disc but i thought it may not be flat afterwoods, A fried suggested a die grinder on it.

Re: Xantia rear brakes

Posted: 05 Mar 2012, 20:46
by CitroJim
Sorry!

A good cold chisel is very quick at doing the job and likely quicker than messing around with grinders. With a die grinder you risk taking big lumps out of the soft alloy of the caliper...

Re: Xantia rear brakes

Posted: 05 Mar 2012, 20:50
by imperial21
Ok, In that case its a grinder for sharpening the chiesel !!! Thanks Jim