Citroen C5 X7 2009 wagon rear left excessive brake pad wear

Andy N

Andy N

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Fellow Frogger
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Can anyone explain what might be happening with the C5 rear brakes left side? I replaced both rear discs and pads back in October and it hasn’t been 3 months and the pads have worn right down and damaged the disc again. When I changed them last it was because the pads in the rear left had worn right down and damaged the disc. I assumed that on the previous service they had only changed one side, now I know that’s not the case and there is a fault with the rear left braking.

My question is, can I adjust the rear brake bias and would it be that or is it more likely to be the electric handbrake not releasing on that side?
IMG_9467 Medium.jpeg

The whole caliper was skewed in addition to the problem so not only did it wear the pads but did so on an angle.

Any thoughts appreciated😉
 
I've put a new set of pads in and noticed the retaining spring had come off so I'll need one of those. And with both rear wheels off the ground I can see the electric handbrake cable tightens and clamps the brakes, however when I release the handbrake the right wheel spins freely but the left is still grabbing a little, despite the cable loosening off. I can only assume the handbrake mechanism at the caliper is sticky. Is this a part that can come apart and be freed up or should I start ordering a replacement?
 
Hi Andy,

I thought the rate of pad wear must indicate that the caliper is not releasing properly. Also the floating caliper seems to be tilting vertically and horizontally as if the mounts have lost rigidity.

Are the bolts 12 tight and the pins 6 the caliper slides on free and not worn. At least this diagram below will give you some part numbers.

Cheers, Ken

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Hi Ken, Thanks for the parts diagram, yes the bolts number 12 were tight and the bolts number 6 yet somehow the caliper became skewed. It looks ok with the new pads in however I did a separate test with brakes applied and released, the pads are free. But with handbrake activated and then released, the pads are binding. Yet the cable is loose so I doubt it’s an adjustment issue. The bolts numbered 6 had a film of rubber that I cleaned off and applied a very light smear of copper grease. Seems to be the caliper not retracting enough when the handbrake disengages. Yet the wind in tool seemed to have little trouble winding it in. Perhaps I just need to run a calliper seal kit through do you think?
 
That’s a good guide Driven, and I will be replacing the guide pins even if they aren’t the main issue. But the bushings the guide pins sit in have had a rough time so they are worn which allowed the caliper to skew. The caliper isn’t retracting properly being the biggest concern. If I release the guide pins and that released the pressure on the pads then it would be guide pins, but it seems more the caliper. When I fitted the new pads before there was always a strong brake smell which I thought was a normal part of the bedding in, but it was the brakes stuck on! And I would’ve driven less than 1000km’s to go from full pad to metal.
 
Andy
Some generic comments and thoughts. Possibly you can strip the caliper clean the pistons and seals and if OK lubricate them inside with special brake grease which is readily available and is compatible with brake parts. Or fit new seals and use the same special brake grease on reassembly. Pack some under the boot also.
The handbrake mechanism usually has a short travel with an adjuster to take up the slack as the pads wear. The piston travel is very small and clearance is also small when off. This can be a problem area. So the guide pins and bushes are important to ensure it works evenly and does not skew. Check and replace those and also ensure the cable is running correctly and not pulling unevenly for any reason.
It may also be possible that the bracket 5 may be bent in some way by some previous accident or some part not correctly machined from new even ?? It seems that a careful inspection of the whole arrangement and comparison to the other side should give some answers.
Good luck jaahn
 
Andy N said:
The bolts numbered 6 had a film of rubber that I cleaned off and applied a very light smear of copper grease.
Click to expand...
A few may be synthetic though I think many 'copper grease' products are still parrafin based and may affect rubber. I suggest using copper grease/slip only on the caliper mounting bolt threads to stop them seizing, and on your wheel studs/bolts every time you take the wheels off :)

www.autotorque.news

Delphi does not recommend the use of Copper Grease

There’s a widespread view that copper grease, otherwise known as copper slip, should be applied to the back of brake pads to help lubrication and noise prevention. Not so. The need for copper grease has
www.autotorque.news www.autotorque.news

Andy N said:
It looks ok with the new pads in however I did a separate test with brakes applied and released, the pads are free. But with handbrake activated and then released, the pads are binding. Yet the cable is loose so I doubt it’s an adjustment issue.
Click to expand...
Andy N said:
Perhaps I just need to run a calliper seal kit through do you think?
Click to expand...

My guess is the shaft for the handbrake is binding in the caliper, look for a rebuild kit that includes new bushes for the guide pins and handbrake lever shaft and also includes the correct brake rubber grease.

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Thanks Jaahn and Alex for your considered and very helpful advice. I didn’t know that about the copper grease so I’ll make sure to use the correct brake lube. The bracket 5 was on tight and straight, however I think I’ll fit the bolts with loctite and good torque. The guide pins skewed with the pad retaining spring having come off. Guide pin bushes and a new spring is needed and I may as well order a new piston and seal. I can only hope the handbrake lever shaft is ok but if I can get that part too I will, because it’s the operation of the handbrake not allowing the caliper piston to fully withdraw. If I brake and release the piston goes home but handbrake and release it doesn’t withdraw fully.
 
Alex again some generic comments.
Any metallic type grease will be mixed in an oil base to make it easily applied. It is OK to use on metal etc parts OUTSIDE the sealed hydraulic brake system, but not on any "rubber" type parts as the oil base may cause deterioration or swelling. That is why special rubber grease is made. It works OK as normal grease too and I always packed it in the boots of drum brake pistons as well as on the bore/piston etc, to help prevent moisture getting in and corroding them.
The item 6 spring is called a caliper lever spring but that is an unlikely name IMHO as the lever is on the other side. It looks like a "pad anti rattle spring", commonly fitted to most cars in some odd shape. Translated names are often not correct. Looks to be available if you google the part number Citroen 4427.E3. These missing do not usually cause that sort of fast skewed wear but may contribute if there is another problem with retraction. As Andy said, I would check the handbrake lever and internal mechanism. Strip, clean and lube with brake grease. Not uncommon for them to sieze up at the entry to the caliper. Possibly Ken might give a diagram of those parts as well. :cool:
Good luck Jaahn
Do not use too high grade locktite as the bolts can be hard to remove anyway.
 
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Thanks again Jaahn, yes I feel you are right about the handbrake mechanism in the caliper and/or the mechanical lever going in. I don’t know how this works to act on the piston but it makes sense if this is preventing the piston retracting somehow. I’ll remove the calliper and strip it down to see what I need to order or free up/ lubricate with the right stuff thanks again for reiterating that Ringer. 🙏
 
I finally got around to removing the caliper piston from the cylinder and may have found the reason why it is binding. There is a fair bit of scoring in the cylinder bore with little damage to the piston itself.

I ended up getting pistons and seals plus guide pins and bushes for both rear calipers but I think I need two new rear caliper units. The right rear caliper cylinder has a little bit of scoring too, not as bad as the left side but still needs replacing before it starts to seize up.

Any ideas how this damage could’ve happened? The brake fluid needs a complete flush out as it was very dirty. I wonder if grit has got in somehow? I didn’t see any dirt or metal fragments which I expected to see with so much damage to the bore.


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The brake caliper rebuild kit I ordered doesn’t have the internal threaded tube spring and washer in the pistons. So not sure if I can use these. The inner face of the old pistons has worn and has an edge whereas the new pistons have a nicely rounded smooth inner end.

I can try my luck with calipers from wrecking yards but would prefer to buy new. Does anyone know where I could get two rear calipers?

Thanks,

Andy

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The brake caliper part numbers are
96 866 482 80 (rear left) and
96 866 483 80 (rear right).
I’ve tried both EAI and ASV but they don’t stock these.
Anybody wrecking a C5 that could supply the parts?
 
You could also try Dapco. I noticed that the Estonians have several brands of them for 50 odd Euros, but air freight has to be added.

For wreckers in NSW you could try ATwins and STwins.
 
Get guaranteed new good ones from a reputable eastern EU source & pay the DHL freight. It will be not too expensive in the scheme of things compared with labour cost & you'll have in about 5 days. I just bought pads & rotors for a SAAB all round for about $450 incl. freight.
 
Thanks for the feedback and suggestion for parts supply. A friend came over with a keen eye for these things and we came to the conclusion that what happened is the result of two problems. The first problem is it looks like water has got in somehow to the far inner part of the piston where the plunger sits. The corrosion has blocked the tiny hole and it seems the plunger hasn’t been able to fully bed in with a dirty mixture of fluid water and gunk stopping it retracting fully when the caliper or handbrake releases but especially the handbrake release peg.

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Plunger wire brushed and new seal fitted with silicone grease. The hole in the recess near the end of the piston is what was blocked in the problem caliper piston.
 
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