C5 rear caliper corosion cleanup

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skinhead
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C5 rear caliper corosion cleanup

Post by skinhead »

the usual action is to clean & apply copperslip to the mating faces of the caliper & suspension arm. Would red hermatite be better to use ??

citronut
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Post by citronut »

well AndersDK say's an aluminium grease should be used

regards malcolm

fred1
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Post by fred1 »

Hi,

I have had great success using a gasket of thick polythene between caliper and suspension arm stuck in place with copper grease.

Put in at about 70k when callipers removed to sort out bad corrosion.

Now some 60k+ later no sign of corrosion.

Callipers removed this week to replace rear arm bearings - garage reported no corrosion and put back the same (home made) gaskets.

Regards

John

citronut
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Post by citronut »

the only prob i see with that is the calliper to disc run out

regards malcolm

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myglaren
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Post by myglaren »

Only needs to be a very thin gasket to prevent the EMF between the steel and the aluminium.

With hindsight, perhaps Coppaslip, or anything with metal in it, wouldn't be such a good idea as the metal particles will conduct and possibly not have the desired effect of isolating the two. Maybe a silicon grease would work better?

skinhead
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Post by skinhead »

My thoughts on Hermatite red were that it tends to fill/even out surfaces,it does not set hard so its easy to remove the caliper again if needed & is water/oil resistant & would not displace the /missalign the caliper,

However I'm no expert & was seeking the thoughts of others with more knowledge

I had my rear calipers done 4/5 months ago by a citroen indipendant who I think only used grease & now the fault is back .I thought if I was able to tell him what was required I might get a longer lasting job done

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Kowalski
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Post by Kowalski »

I used wire rope grease on my Xantia calipees and it sorted them permanently. Wire rope grease is black and sticky and very water resistant, so it stays put.

fred1
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Post by fred1 »

A "thick" polythene is still only a fraction on a mm thick.

It has no effect on disc to calliper alignment, certainly much less than the effect of the corrosion building up which starts very soon after a "normal" clean up and grease.

Pad wear subsequently has been excellent, very even and long lived.

John

skinhead
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Post by skinhead »

kowalski, Fred thanks for your replys

Fred are you refering to something like a heavy grade plastic sack material?
or some thing more rigid?

Kowalski I know what you are refering to but where would I get it from?

fred1
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Post by fred1 »

Hi,

Just thick clear polythene bag and cut a piece out.

About the same thickness as the ones you buy nails etc in a B&Q.

John

skinhead
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Post by skinhead »

fred1 wrote:Hi,

Just thick clear polythene bag and cut a piece out.

About the same thickness as the ones you buy nails etc in a B&Q.

John
Thanks for the reply John

Regards Tony

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AndersDK
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Post by AndersDK »

The main idea is to seal off the mating faces against salty road mist & humidity.
You can use just about anything that keeps out the water. Any kind of thick sticky grease or soft water resistant gasket material will do the job great.
The electro chemical corrosion of any copra/alu paste is in-significant in this aspect.

There really is no secret to it - just keep out future water ingress once you have invested so much time & effort getting things right again 8)

fred1
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Post by fred1 »

The reason there is a problem is that the interface between the callipers and the rear arm is between dissimilar metals and the electro chemical potential that is set up. Salt and water help form the resultant cell.

If you can keep water and salt out - which is difficult given the location of the callipers

or

keep the metals out of contact - which is easier- then you prevent corrosion.

Using an insulating gasket to prevent contact seems to be the most effective/reliable method.

Regards

John

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Kowalski
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Post by Kowalski »

skinhead wrote:Kowalski I know what you are refering to but where would I get it from?
The wire rope grease I used came from Bretts Oils in Newcastle, it came in a rather large tub, i.e. much more than you want to buy to fix your Xantia, its not really a consumer product. The particular tub was bought because it was the lubricant reccomended for lubricating the slides on the extending rear arm on a JCB, if you could find somebody who maintains heavy plant they may let you have a small amount.

Wire rope grease is thick and sticky, its rather like heavy fuel oil in consistency and needs to be heated to be applied, perhaps you could use bitumen in it's place, again it would need to be heated to be applied.

skinhead
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Post by skinhead »

thank you all for your very informative replies you have been very helpfull


regards Tony