pad wear

merseyscouse · Unread post by **merseyscouse** » 23 Apr 2005, 21:25

last year about 10,000 miles ago i had new pads and discs fitted by the dealer to the front of my hdi 110 xantia, the nearside had chewed into the metal.
I have just noticed the same grinding noise starting from that side and on taking my front wheel off it appears that the pad is worn down again, i also noticed an increase amount of brake dust on that side.
the brakes including the handbrake seem to work fine.
any suggestions??? [:(]

BX-Basis · Unread post by **BX-Basis** » 23 Apr 2005, 22:33

Has the brake cylinder been turned back into the correct position ? If not that might cause extreme wear of one of the break pads.

Kowalski · Unread post by **Kowalski** » 23 Apr 2005, 23:58

Ignore the comment above about the cylinder being turned back in. It doesn't matter where you adjust the piston to, it'll adjust itself to the correct place the first time you apply the brakes, if its too far in you won't be able to fit the pads at all.
It sounds like you've got a dragging brake which either means the caliper slides are sticking (most likely if only one pad on one side wears prematurely) or the piston being sticky (if both pads one one side wear badly).

BX-Basis · Unread post by **BX-Basis** » 24 Apr 2005, 01:07

Sorry, but it is in fact necessary to turn the piston into the correct position. Since the introduction of the integrated handbrake on the BX, there has always been an additional marking on one of the four notches in the cylinder that has to be adjusted correctly. If the piston is not adjusted correctly, the brake does not loosen correctly and you have the phenomenon of worn brake pads on only one side. Of course there could also be a problem with the caliper sliders, but the correct position of the piston is very important, too !

zzf00l · Unread post by **zzf00l** » 24 Apr 2005, 01:11

??? News to me BX-Basis

Stuart McB · Unread post by **Stuart McB** » 24 Apr 2005, 01:11

Now,now boys. Does sound like a dragging pad though. I do agree with kowalski though.

Kowalski · Unread post by **Kowalski** » 24 Apr 2005, 05:08

On the Xantia you have to line up a notch on the outer piston with the lug on the back of the pads otherwise you can't swing the caliper up or down over the brake pads, when the caliper is in position the lug is in the centre of the piston. As I said above, the first time that you apply the brakes the piston rotates so whatever position you left that notch in it'll be in a different position after it adjusts itself.
In any case, the Xantia has a single piston free floating caliper and the only way that one pad can wear more than the other is if the caliper isn't free to float. If the piston was badly adjusted somehow it would wear both pads. In any case, since the calipers are self adjusting, if you set it up initially so that the piston was adjusted to be too tight, some initial brake binding would happen but only until the pads had worn a little so that there was clearance between pads and disc, then normal wear and adjustment would happen.

merseyscouse · Unread post by **merseyscouse** » 24 Apr 2005, 05:31

Hmmm interesting but no definitive answer, as i said this work was carried out by the dealer and obviously it is the second time that one pad has excessivly worn out.

AndersDK · Unread post by **AndersDK** » 24 Apr 2005, 05:51

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

Hmmm interesting but no definitive answer, as i said this work was carried out by the dealer and obviously it is the second time that one pad has excessivly worn out.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Kowalski does in fact mentions it above : the caliper is a free sliding single piston type.
If - for any reason - the caliper does not slide squarely on the sliders - it will stick and then only the piston can move out with it's one side pad. Thus only this one pad (against the piston) would wear.
I believe there is a problem in the sliding mechanism - which SHOULD have been serviced at the last brakes service.
Personally I'd add that I do NOT like to pass the 6Kmile without at least visually have checked the brakes. Brakes wear are quite dependent on personal drivestyle - which not exactly means racing the car everyday.

fastandfurryous · Unread post by **fastandfurryous** » 24 Apr 2005, 06:57

one thought... did the old pads wearing right down do any damage to the disc? if the surface was damaged and not replaced, then it may have caused premature wear of the pads.
I used to have a very similar combined handbrake/hydraulic caliper on the rear of an X1/9. Winding the piston back in was essential, but as long as it was in far enough to get the pads in, then that's fine. It used a very clever 5-start thread and a one-way clutch, all in the back of the piston. I've never pulled one apart, but I guess the xantia is similar.

David W · Unread post by **David W** » 24 Apr 2005, 15:00

This is really common on many Xantias without any really obvious problem on a caliper or its slides. You can fit a new set of discs and pads , having checked the calipers appear to move freely and that the pistons wind back in OK..... yet 10,000 miles later you might see excessive wear on just one of the four pads.
The weird thing is that it isn't always the same pad that wears first on any particular car.
I accept it as "one of those things". What you can do if you are happy with it is to always keep to the same brand of pads and then save the best from a set taken off then you have a spare to put on in place of the excess wear one. This is only OK if your discs are good and haven't worn the pad you intend to re-use to an odd shape.
It's only a thought but sometimes I wonder if it is anything to do with the handbrake cable arrangement lightly pulling on the handbrake under some circumstances... like when turning??
David

gjb02 · Unread post by **gjb02** » 24 Apr 2005, 15:14

Kowalski briefly mentioned pads sticking in the guides earlier I think that is a more viable reason.
The reason I don't think the caliper slides are the reason is, that they don't come into effect until there is some real wear on the pads. When the pads are new the caliper sits in the same place hardly moving when the brakes are applied. It doesn't have to glide or slide into place when the piston pushes and the caliper squeezes.
My experience of most Dealers is that they don't clean up the guides or apply any kind of coppa slip to reduce the chance of the pads sticking. In some cases I have had to hammer brand new set of pads out of a caliper because they had just been, 'fitted'!! Literally placed in the guides and the caliper fitted on top. Then physically pushed into seizure by the first application of the foot brake.
This after a short time will lead to the pads glazing, excessive pad wear, the familiar brake burning smell and warped discs due to overheating. Not to mention excessive fuel consumption.
No checking to see if the pads where a tight fit beforehand, no check for excessive corrossion or brake dust build up, just chuck them in.
There's fitting and there's assembling...a mechanic fits, a technician assembles.
One takes half an hour and claims for an hour! The other takes an hours and claims for the same.
I digress![:I]
Change the pads yourself! Haynes BOL will tell you how.
Here's a brief description of how I would do it. Not in exact order!
Unbolt the caliper from the guide and move it out of the way. Place the pads in the guides and move them back and forth in the same motion the caliper would. If it's a good fit there should be a slight resistance to free and flowing movement.
If they are tight you will know, so clean up the guides. A wire brush or even the edge of a flatblade screwdriver, if build up is heavy, will do the job.
Protect the face of the brake disk while you clean, or better still remove the guide from the hub, altogether. Periodically check the fit of the pads in the guides, when free movement is acheived, reassemble.
Once the guide is refitted to the hub apply a small quantity of copper grease or similar to the guides, where the pads will sit, but don't go mad.
Be aware that brake dust is hazardous, wear a paper mask!( Not that I ever have![:I])
Torque tighten and use thread lock on bolts, where required, on reassembly.
The Haynes BOL will detail a brake pad change very accurately, but no mention of ensuring the guides are clean on reassembly!![:o)]
[:I]I'm gonna get some comments about this!![:I]

fastandfurryous · Unread post by **fastandfurryous** » 24 Apr 2005, 16:24

Only comments of agreement! certainly about the attitude of most dealers and garages!
The only thing I disagree with is the statement that the slider doesn't come into effect until there is some wear in the pads. It comes into use straight away, after all, how else is the non-piston-side pad to press on the disc?
I have experienced similar problems with most of the cars I've had with single piston sliding calipers. What often happens is that the sliders become partially siezed, and are able to pull the "slider side" pad on, but it won't come off again properly, and so wears out really fast.
What still amazes me is that cars even have single-piston sliding calipers. The first car I ever changed the pads on was a Talbot Horizon, which had fixed twin-piston calipers, and NEVER siezed in the slightest. Every car I've worked on since has been a dissapointment in terms of technical development: They are made down to a cost, rather than up to a standard of quality!
David

merseyscouse · Unread post by **merseyscouse** » 24 Apr 2005, 19:15

I dont know if there is any relevence here but the first time the pads were done was in a non franchised garage, the manager told me the brakes were not what he thought should be on a xantia, they had to take the pads in to the motor factor to get them matched...i think he said they were off a peugeot?????? As i said the last time they were done was by a franchised garage and he did not comment..
Is it remotely possible that the wrong pads could be fitted????they did replace pads and discs.

Kowalski · Unread post by **Kowalski** » 24 Apr 2005, 20:33

The Xantia comes with 3 different sizes of disc and FIVE different pad sizes.
The largest discs (the 288mm which the HDI 110 comes with) can have one of three different pad sizes, hence the confusion.