Facelift C5 (not X7) rear brake anti rattle

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Dommo
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Facelift C5 (not X7) rear brake anti rattle

Post by Dommo » 02 Jul 2018, 11:55

Hi all

I've been having a rattling issue at the back of my C5 since I've bought the car, and since the nice weather I've been driving around a lot more with the windows down. For the record my AC does work but for short trips I sometimes prefer the windows down.

I noticed that the brakes being applied, stops the rattle completely, so I thought I'd have a look on servicebox to see if there is any suggestion on there as to what anti rattle components there are. Looking at the first attachment from ServiceBox, you can see part 8 - anti rattle 2 shim set - which my car doesn't have. If you ask me, part 8 looks to be an addition after these diagrams were initially drawn up.
Brake Components.png
Service Box image
Thought I'd take a look in the Haynes and sure enough this part isn't in the photos.

So I ordered some from Citroen for around £20 for the pair, along with a new brake fitting kit from Euro Car Parts for a whole £9, in the hope this will stop my rear brake pads rattling. However now I have them, I can't really see what difference they'll make. See the photos below for the shim and fitting kit 'constructed'.

Am I being an idiot, I can't see how this will help anything?

Cheers.
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Dommo
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by Dommo » 02 Jul 2018, 11:57

Apologies about the angle of the photos, on my phone they don't show up on their sides, so I'm not sure why they do here!
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MikeT
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by MikeT » 02 Jul 2018, 12:08

AFAIK, along with anti-rattle shims, some components are designed to stop brake pad squeal too.
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by GiveMeABreak » 02 Jul 2018, 12:09

You'd be surprised - rather than repeating - have a look here for an explanation:
https://auto.howstuffworks.com/auto-par ... -shims.htm
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by Paul-R » 02 Jul 2018, 12:17

Well I have a problem with that so called explanation in the first sentence. The shims do NOT fit between the brake pads and brake discs (rotors they call them). They sit between the pads and the pistons of the caliper. I didn't bother reading further if they can get something so basic wrong.
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by white exec » 02 Jul 2018, 12:44

That HowStuff... 'explanation' is more than a tad confusing, IMO.
Shims and anti-rattle springs are quite different things, and there to tackle separate issues.

Shims are there to reduce squeal, by acoustically coupling the brakes pad to the heavy metal caliper, which, being heavy, isn't capable of vibrating at a high frequency. Shims may be plain steel, or plastic or mastic coated, and are there to provide better contact between pad and caliper than could be achieved with the pad alone. Shims may be single or double on each side. Traditionally (and especially with plain steel shims), adding a smear of copper grease to the shim/pad/caliper contact surfaces improves the acoustic contact.
Some brake pads are mastic-coated on the backs, intended to bond/anchor themselves to the caliper. Other pads don't have this, so shims/brake grease can be important.

Anti-rattle springs are there to stop the pads chattering/clunking up and down (and in and out) in the caliper, when the brakes are relaxed. The a-r springs should apply a continuous pressure on the outboard edges of the pads, not dissimilar to pressing firmly there with your finger.

Bumpy ground can produce rattle, which will stop when brakes are applied. Squeal is just that - squeal - and often happens under light braking. Many Citroen rear disc brakes don't do a lot of work under normal use (front brakes do the lion's share), and pad surface can become glazed (polished), which encourages squeal. Some deliberately hard braking can sometimes get rid of it, until next time.
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by GiveMeABreak » 02 Jul 2018, 12:50

Bad example - I think that chap was getting mixed up with calliper shims used to correct the disk and calliper alignment :roll:

Anyway you get the drift - some also have a backing plate that goes behind the pad too on the rear pads to further reduce vibration / heat / noise etc.

This chap is doing a replacement and you can see the plates at about 14:58 and again when fitting at 17:58:

This is on a MK I C5, but informative:

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Re: Facelift C5 (not X7) rear brake anti rattle

Post by Gibbo2286 » 02 Jul 2018, 13:10

I've not seen those metal plates before, maybe an addition to the x7, usually there's just the wire anti rattle held in place by the through bolt, looking at the pictures are you sure you have them the correct way round in the wire, I would have thought that the flat face would go against the edge of the pads.

I like the guy's safety boots in your video Marc. :-D
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by GiveMeABreak » 02 Jul 2018, 14:17

None of those on my X7 Gibbo - so maybe those were a MK I feature or an aftermarket solution perhaps?

Yes, loving the Carlos Fandango super safe mechanic's flip flops with built in invisible steel toe caps!
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by GiveMeABreak » 02 Jul 2018, 14:21

Yes, just confirmed, they are part of the rear brake kit for the MK I - see part 3 - they can be seen next to the pads.

They are also on the MK II, but not on the X7 - so they probably modified the design and built them onto the back of the pad perhaps - I've never had any squeaks on mine.
C5 MK I Rear Brake Kit.PNG
So you would get these if your ordered the kit - but not if you just replace the pads - so one assumes these are reusable - as the guy seemed to be doing in the video, cleaning them off.
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Re: Facelift C5 (not X7) rear brake anti rattle

Post by Dommo » 02 Jul 2018, 14:55

The shims you're on about on the back of the pads have been fitted to every Xantia I've owned and the Mk1 and Mk1 facelifted C5's as well. They are usually reusable, but I've had a set of pads before where they were bonded to the back of the pad so obviously they weren't removable on those.

The part I'm on about is part 8 on servicebox - you can see it looks like an addition to the image.

Gibbo you might be right about it being the wrong way round, hence me asking! Can't see any info about it online at all.

Cheers.
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