Front brake pad wear.

Post by **user_3150** » 23 Feb 2006, 20:38

Hi everyone, just replaced the front pads after hearing a bit of metal on metal action. Anyway the outside pads were on the metal but the inside had only worn about half way any ideas? Seems a bit strange as the car pulls up well and brakes O.K on MOT brake tester. Checked the calipers and they are floating very smoothly. They don't bind (or at least I can't feel it) and the pistons seem to be moving freely.

8304 · Post by **8304** » 23 Feb 2006, 20:51

how many brake pistons do xantia have on the front??

if it is one there will be a slider arrangement whereby the single piston pushing out on the pad causes the whole caliper arrangement to slide on sliders pulling the other pad onto the oposite side of the disc.

it xantias have single pot calipers on the front it is almost certainly the sliders ciezing.

anybody else, do xantias have single pistons on the front????

zzf00l · Post by **zzf00l** » 23 Feb 2006, 21:19

Yes hey are single cylinder..... and very simple to keep free, just use copperslip or similar

8304 · Post by **8304** » 23 Feb 2006, 21:26

as the sliders have obviously started to jam it will be neccessary to dismantle then.

there is a 17mm bolt (i think) at the top and bottom of the caliper, these can be removed and the metal sleeve which acts as the slider removed - it will be stiff becuase this is the fault that is causing uneven pad wear...

they will need cleaning will wire wool or fine emery paper, greaing and re-assembling. its not a bad jod - ive done it on the front and back of my zx...

have fun

alastair

Post by **user_3150** » 24 Feb 2006, 06:38

Thanks for the replies. The calipers are sliding freely this is what I can't work out. I checked the calipers over when changing the pads and all is well in the movement front no catching or seizing. What I might do is take off the calipers and see if there is some debris on the slider shaft and re-grease as 8304 Alistair says. (this will obviously go onto my summer Xantia to do list along with a few other's). Cheers Alec

Mandrake · Post by **Mandrake** » 24 Feb 2006, 09:04

Unfortunately this seems to be a common problem with Xantia's, and may well be a design flaw, it seems that uneven wear between the innner and outer pads happens on most of them despite the calipers seeming to slide smoothly and being lubricated.

It may have something to do with the fact that they only have one slide pin instead of the two more commonly found on single piston calipers...

Regards,
Simon

G4EIY · Post by **G4EIY** » 24 Feb 2006, 09:28

I have read in the past, if a car is left for long periods in moist or wet weather conditions, and the car is not used often, then the rust build up on the outside face of the disks can produce premature wear on the out side pads.

I have never found this to be a problem though..

Good luck.

AndersDK · Post by **AndersDK** » 24 Feb 2006, 13:20

Mandrake wrote:Unfortunately this seems to be a common problem with Xantia's, and may well be a design flaw, it seems that uneven wear between the innner and outer pads happens on most of them despite the calipers seeming to slide smoothly and being lubricated.

It may have something to do with the fact that they only have one slide pin instead of the two more commonly found on single piston calipers...

Regards,
Simon

It is in fact a common problem with ALL type sliding calipers. Once the sliding bores/bushes becomes a bit worn, they tend to stick because they are able to move a bit sidewards and then lock under braking. You dont notice this during a service job as they simply slide perfect and freely when you test ...

I get this problem all the time with the BX'es in my stable. Only remedy is to replace the slider bushes. Sometimes the solution is to clean (rub down) the contact end face of the bushes - and the hub mating face. I.e. the same type of problem when corrosion gets in between rear calipers and rear arms.
This makes the calipers slide out of true.

cosb6 · Post by **cosb6** » 06 Mar 2006, 13:08

The same used to happen on my VW Polo, and MG ZR.... it's very common because of the simple design..

Personally, as long as the brakes work correctly, I wouldn't worry unduely....

stevieb · Post by **stevieb** » 06 Mar 2006, 17:31

Would it be worth polishing the sliders at all...?

A light polish with a little bit of Brasso or Molybdenum paste might just return a nice shine and allow the grease to act more effectively. I know when I've dismantled these in the past the sliders always look quite dull, and considering the movement they have you'd expect some shine on them.

Just a thought...

zzf00l · Post by **zzf00l** » 06 Mar 2006, 19:32

Sounds like a reasonable idea to me..... However, to prevent getting to this stage, a light smear of suitable grease as preventative maintenance is best.