xantia rear brake excessive fluctuation

[John Plum]

My question regarding an MOT failure for rear brake excessive fluctuation is, if the rear height corrector cylinder is not good (permits sinking) would this affect braking efficiency and balance?
Its a Xantia MK 2

[CitroJim]

No, not when the engine is running John...

I suspect you have the old familiar 'wedging' problem and need to overhaul your calipers... There are plenty of threads about this very subject and the precautions to be taken..

Have a look at this thread to gain an idea of how to remove the caliper bolts safely and how to clean up any corrosion...

https://www.frenchcarforum.co.uk/forum/ ... hp?t=31410

[Hell Razor5543]

This is the first thread I posted on, with the same issue. It also has decent photographs clearly showing what the problem is;

https://www.frenchcarforum.co.uk/forum/ ... =3&t=38467

[John Plum]

Muchos Grathias gentlemen

I did a complete overhaul a couple of years ago. But I'l be taking a close look to see how they have fared. Possibly jus need bleeding and re-greasing on the slide. I had used copper slip, but I'm thinking they need something better.... whatever that might be. They started to squeal.

[CitroJim]

James, thanks for posting up that link I was looking for it but could not find it... I must 'SuperSticky' it now it's found again...

John, when you last overhauled the rears did you replace the thin tin covers over the calipers? I ask as I've seen them discarded in the past and that's a recipe for lots of road crud to contaminate things badly...

[John Plum]

Ah well, Jim, thats a very good question:
I did everything, even red oxide on the cleaned-up metal, and used a paper gasket, But: Replace those tin covers? No. The sheer time delay and hell of getting them on an awkward journey.... I felt bad about it at the time, but managed to forget about it.

Do you reckon they are even available?

[xantia_v6]

BTW, you shouldn't use copperslip or similar metal-loaded grease on any joints that move in normal operation, as it is slightly abrasive and will cause wear.
You also shouldn't use on brake calipers, as it is not temperature stable, and when the brakes get hot, it will run and contaminate the pads (which could be your current problem).

[Hell Razor5543]

The other problem with using a metal based grease is that the corrosion is caused by an electrolytic reaction between the metal of the calliper and the training arm, and adding a third metal to the mix may well make things worse. I have considered putting a thin piece of plastic between the arm and calliper, to act as a shield between them.

Euro Car Parts do have those rear brake kits available, and are not expensive (under £10 for both sides), but I would check the kit before leaving the store. The first one I bought had a split in the bag, and a few bits were missing. The salesman agreed that this was not my fault, ordered another set, and checked it personally when it came in.

http://www.eurocarparts.com/ecp/c/Citro ... 30c&000416

[John Plum]

The other problem with using a metal based grease is that the corrosion is caused by an electrolytic reaction between the metal of the calliper and the training arm, and adding a third metal to the mix may well make things worse. I have considered putting a thin piece of plastic between the arm and calliper, to act as a shield between them.

I cut a paper gasket, spread it with grease, and used that. Worked nicely. Now poised to re-inspect after two years...

[Stickyfinger]

The other problem with using a metal based grease is that the corrosion is caused by an electrolytic reaction between the metal of the calliper and the training arm, and adding a third metal to the mix may well make things worse. I have considered putting a thin piece of plastic between the arm and calliper, to act as a shield between them.

I cut a paper gasket, spread it with grease, and used that. Worked nicely. Now poised to re-inspect after two years...

Would be nice to see the strip down photos to see the results of that.

[John Plum]

Here you are then: a link to my previous overhaul, with gasket visible in pictures:

https://www.frenchcarforum.co.uk/forum/ ... 19#p425819

[CitroJim]

John, that's valuable link back to a valuable thread on this subject

Very interesting comments on the use of copper grease, thanks for that. Stuff I was unaware of...

[c.morewood]

I do this every year just to check on the brake condition. But I found that greaseproof paper was only lasting one year and needed replacement each time. Someone on the forum suggested the thick black damproof plastic membrane. I've used that for nearly 3 years with no problem. The easiest way to ascertain whether you have a problem with the back brakes is to jack each side up in turn and give the wheels a good turn.. they should turn with hardly any resistance and rotate at least 3 or 4 times before stopping. If they don't you need to strip the brakes.

[John Plum]

The easiest way to ascertain whether you have a problem with the back brakes is to jack each side up in turn and give the wheels a good turn.. they should turn with hardly any resistance and rotate at least 3 or 4 times before stopping. If they don't you need to strip the brakes.

Ive inspected the 1mm gasket paper (greased) - its fine. Your spin check is a good one. mine are not spinning nicely , unlike when when I last re-fitted them with all new pads and discs. Although I cleaned ups and greased the pins and edges nicely at that time, I think it probably needed new pins. I'm about to take off the pads now to inspect them.

[Hell Razor5543]

Well, ECP do sell the rear brake kits, with the covers, springs and all.