X7 Unexpected Rear Brakes Change + Coated Brake Discs

[Sloppysod]

Yes running or bedding is is basically braking lightly for about 100 miles or so, I think the theory is that you don't create too much heat.

As for use of copperslip, I agree cannot see any point stopping using it on steel to steel parts, but I will stop putting it between dissimilar metals, actually, I have been using vaseline between hub and wheel centres for a while.

Condition of wheels, mine too are bubbling up and a refurb is on my to do list, using a etching primer to calm the corrosion. It is not just X7 wheels, I had a 2011 C4 and managed to get a set of wheels from citroen under a warranty claim.

[Gibbo2286]

Yes running or bedding is is basically braking lightly for about 100 miles or so, I think the theory is that you don't create too much heat.

As for use of copperslip, I agree cannot see any point stopping using it on steel to steel parts, but I will stop putting it between dissimilar metals, actually, I have been using vaseline between hub and wheel centres for a while.

Condition of wheels, mine too are bubbling up and a refurb is on my to do list, using a etching primer to calm the corrosion. It is not just X7 wheels, I had a 2011 C4 and managed to get a set of wheels from citroen under a warranty claim.

Differing messages on Copper grease depending on the car, the last set I fitted to an 04 C5 mk1 the fitting instructions said "Do not use copper grease on the pad backplates.", the ones I fitted yesterday to the 06 C5 mk2 says "Lightly smear anti seize copper grease on the back and edges of the new brake pad backplates carefully avoiding the friction material and to the caliper abutment slots."

Both by the same supplier 'Delphi'

[EDC5]

The rear calipers of the X7 appeared to be made from aluminium not steel so there may actually be a slight reaction between the caliper and the steel backing plate of the pad.

Although the pads are painted so in theory there shouldn't be any issue thinking about it.

What would be the best grease to use then, to completely eliminate the possible effects of copper on dissimilar metals?

[white exec]

The grease itself will not eliminate the electroytic action, as the action is between the dissilimar metals, in the presence of a conductive solution (salty water, at its worst, but any dampness).
Paint on brake pads will soon wear off.

There's plenty of history of bi-metallic corrosion on cars (usually steel-aluminium), so not good to hear of alu calipers...

[Gibbo2286]

The grease itself will not eliminate the electroytic action, as the action is between the dissilimar metals, in the presence of a conductive solution (salty water, at its worst, but any dampness).
Paint on brake pads will soon wear off.

There's plenty of history of bi-metallic corrosion on cars (usually steel-aluminium), so not good to hear of alu calipers...

Right back in the 1950s, Morris Minor wheel cylinders suffered badly, I once started to explain the problem to a young lady customer but she finished my sentence and went on to say that she worked in the lab at Tucker Eyelet (A Birmingham Company, maker of pop rivets.).

[white exec]

...and steel pipe unions, screwed into aluminium valve bodies and cylinders.
One reason why Citroen fabricated most of its hydraulic suspension components from steel.

[EDC5]

A follow up a mere day after fitting the new brakes.

I went for a short drive, around 10 miles on a dual carriageway but upon arriving I could smell brakes burning. I found that the rear passenger side wheel was hot! bad news. I gave the caliper a few knocks with the tyre wrench before returning to base slowly. When I got back the brake caliper on that side was hot but not overheating.

I had an idea that it may be the slide pins which were to blame so I took one off for a look:

It had a layer of filth on it preventing smooth motion of the caliper.

I cleaned them up with brake cleaner as a slightly abrasive pad before a liberal application of grease and refitting the whole calipers.

I've been for a short drive now and all appears well. I'll have to repeat the longer journey tomorrow to confirm.

Just wish I'd remembered to do it yesterday

[MikeT]

Thought I'd tag this example onto this thread.

04 C5 Rear Caliper crumble.
Check out the first 2 minutes.

[GiveMeABreak]

Saw that a while ago - it's an earlier C5 but the X7s tend to wear the rears brakes pretty much as the fronts I've found, whereas earlier models tended to last a lot longer.

[moizeau]

That was a bit of a mess! Surprised a torque wrench was never used but a good insight.
So that's what Adrian Lewis does when he doesn't play darts.