Hi there.
This might be a stupid question. Sorry if it is
What exactly do anti-rattle shims do? My Xantia doesnt have any in the rear brakes - they are missing. The rear brakes squeel when used most of the time. Applying copper grease has had no effect. Could the lack of shims be the problem? If so, can they be bought seperately? My local GSF don't have them.
I might have asked this before but forgot whether I had...
1994 Citroen Xantia SX 1.9 Turbo Diesel
147,500 miles
They prevent the pads from rattling, I do not think they are fitted in the back brakes at all, or because of the design do they need to be.Remove your brake pads,clean off all dust,use a wire brish,or perhaps also lightly sandpaper your pads,and spray with a brake cleaner(Aerosol).The back brakes do very little work,so perhaps your disks may be a little rusty and also need a clean up.Your mileage is similar to mine,and during the Summer I renewed by front pads,at the same purchasing a set of same for the back,only to find that the thickness of the ones on the car,were almost as good as the new ones(which I returned to the dealer)
Edited by - jmd on 15 Dec 2002 02:03:12
Edited by - jmd on 15 Dec 2002 02:06:12
So they are not required? The Haynes manual seems to mention them, which is what let me to wonder where they were.
We had the wheel off checking the brakes a while back - nice and clean, added some copper grease as well, didn't stop the squeeling.
1994 Citroen Xantia SX 1.9 Turbo Diesel
147,500 miles
Often refered to as anti rattle or anti squeel shim's, they are incapable of preventing or reducing pad rattle, plus there are seperate springs fitted to the calipers dedicated to this task, so they aren't anti rattle shim's.
It is quite likely that these shim's will prevent squeeling in the later stages of pad wear because they maintain a bias on the pad which should mean there is a better contact area between pad and piston.
The side of the pad that encounters the advancing disc as the car travels in the forward direction, in this case the top of the pad, is subjected to the drag effect of the rotating disc, the drag of the disc pulls the top of the pad towards its self, so the force applied to the pad by the piston gets increased at the top of the pad by the amount of drag exerted by the disc, this would cause the top of the pad to wear faster than the bottom.
The smaller the pad and its driving piston are, the quicker this uneven wear would take place since the effect is basicly to try and cock the pad over.
This is where the shim's come in, you will notice that they are cut away to prevent the top half of the piston bearing down on the pad, and when correctly fitted with the cut away to the top, a bias is applied to the bottom half of the pad, this helps prevent the uneven wear on the pad.
Without the shim's the pads will wear away at the top and begin to lean over, when the small amount of play in pistons is used up as they acomodate the ever increasing angle of the pads, there will come a point that they can lean with the pad no further, and will begin to bind in their bores as they apply braking force.
The top of the pad will wear away a bit more due to the drag then stabilize as the piston cant tilt any further, by now the main force from the piston is being applied by its bottom most edge, but because the piston is circular, and pad both flat and at and angle, the contact area transmiting the main force is now very small, this may ultimately lead to a squeeling rear brake.
On large pads such as those fitted to the front this drag effect isn't much of a problem, also the front caliper and piston's are proportionately larger allowing them the apply their force over a greater area of the pad and are not so easily cocked over, which is why you rarely get shims on the fronts now days.
Dave
Sorry to bring up this topic again !
I broke the anti-rattle shim on the front driver side brake while changing pads ! Everything seems to run without much problem even without it. Is there any problem in running the car without this anti-rattle shim ?
thanks in advance
Been reading this thread with interest. My ZX td developed brake squeal at the front. This has happened since I changed the pads last year. I used official pads - but did not se copper grease. I dont think the front had any anti-rattle plates.
The things is the pads seem to squeal as the brakes get warm - and on a warm day will start to squeal earlier. On cold days they are ok for a lot longer - and again only start top squeal after they get warm. Squeal is there on light use , under braking - dissapears.
Pad thickness is ok. I tried cleaning the edge of the disc where rust normally accumalates (not on the disc surface - but the lip - edge of the discs - not made much difference - although pitch of the squeal has changed. I think I'll have to take out the pads and give a good clean and copper grease on the back of the pads.
Discs although not new - ar not ovrely worn. Got about 15k left in the pads. They have lasted about 9k so far.
Squeak Sqeak Squeak. I have had some thin rubber shims inserted between the pad and brake piston on the front disks of my ZX by a local garage mechanic (on his recommendation). Squealing stopped right in its tracks. Dead.
Squealing is a sign that something isn't right with your brakes.
With the Xantia rear brakes it can be a sign that the caliper has been pushed out of true from the suspension swing arm by disimilar metal corrosion.
This is a picture of what a caliper with the corrosion behind it looks like, note the caliper almost touching the brake disc and not running parallel to and clear of it.
If you look at the second picture, you can see the caliper parallel to and clear of the disc as it should be.
When you get corrosion between the caliper and swing arm, the caliper must be removed from the arm and the corrosion scraped from both faces. A little bit of grease between the two before you put them back together will slow the corrosion from coming back (I say slow rather than stop because grease won't stay put, it'll tend to get washed off).
I've borrowed these pictures from a website, but its in french so it might not be so useful. http://nurbo.free.fr/blog/
or the google translation of the same article. http://www.google.co.uk/translate?u=htt ... en&ie=UTF8
Hello,
My front pads were squealing horribly, so bought new pads. This new set squeal too. I coppper greased the backs of pads, cleaned and sparingly greased the contact parts of pads where they sit in calliper. There were NO shims fitted to the front brakes of this car, but there are in the rear pads ( it show this in haynes bol, and you can buy a rear set of shims and pins from local parts factor ). Handbrake mechanism is ok, so I will live with it---sets my good lady`s teeth on edge[:D], but doesn`t bother me.
My son has my old Xantia TD, the brakes are far better on that than this abs fitted car. Never have rated abs--especially on an articulated truck---with 44 ton pushing you, you want to have complete control, not have brakes coming on and off at the whim of a bloody puterized valve set. Sorry---not my cup of tea,
Greg<font face="Comic Sans MS"></font id="Comic Sans MS"><font size="2"></font id="size2"><font color="blue"></font id="blue">
