Mmm........C5 rear brakes.

[lexi]

Just getting teeth into this now. The pesky long bolts. That is not a great design is it guys? A long and stretchy bolt that the caliper hangs onto? I know they are 10.5 but a bit of an ask.
Apart from the corrosion that pushes the caliper off the swinging arm plate, the forces must bend and stretch that bolt badly as well?
My 4 bolts only have half of the heads on them. I had to weld large nuts on them to remove.
On the fourth bolt the beggar broke It went on outside face of caliper.......flush. I will grind a lump out of caliper tomorrow and get another nut on it. I miss my oxy/acy smoke spanner

[dnsey]

The same basic design has been used for a number of models for decades, complete with the corrosion problems. Why they didn't modify them based on experience and feedback is a mystery - even fitting an 'official' gasket would have been a step in the right direction.
I suspect they took it as far as it would go with the C5, and the Loctite coated bolts, which are the biggest cause of removal problems, were a last resort. Perhaps there were problems with the prototypes, and it was too late to re-design the calipers (or rather re-specify, as they're bought-in).
I suppose over time the shear forces on the bolts when braking diminish, as the caliper becomes bonded in place with corrosion!

[citroenxm]

The Xm appears to be the only model that doesnt suffer this caliper problem.. the reason? The caliper face Does NOT cover across the whole of the two mating faces.. the caliper only contacts the arm face in the areas where the bolts pass through... no other lhm citroen used the design .. unless cx do too. One lhm cit ive had nothing to do with yet..

[Stickyfinger]

C5x7 does it in a different way does it not ?

[citroenxm]

X7 isnt an LHM cit and is is more a 407 as the suspension is complete swappable to springs n dampers.. even on exclusive hydraulic equipt cars the hand brake is still on the rear so the x7 actually breaks the rules of trailing arms rear and handbrake on front setup that all lhm and mk.1 c5 have

[lexi]

C5x7 does it in a different way does it not ?

Because of wishbone suspension?
I did a paint job on the new calipers and bolts. Etch primer on caliper side, contact face, then 2 coats of engine block enamel. Same with bolts and their new washers .
Left the thread for the loctite. That is all that the job needed at the factory. Good, suitable paint will stop ally/ steel corrosion.
Ha ha.............all part of Citroen ownership. Good maintenance from PO''s and their garages would have prevented this easily mind. Why do we end up doing these jobs in winter? Masochism is your answer

[Stickyfinger]

The Xm appears to be the only model that doesnt suffer this caliper problem

C5 is the only one that suffers...Xantia does not have the problem either does it ? (hope not )

[Hell Razor5543]

The Xm appears to be the only model that doesnt suffer this caliper problem

C5 is the only one that suffers...Xantia does not have the problem either does it ? (hope not )

Sorry Alasdair, but the Xantia does suffer that weird corrosion as well;

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

[Stickyfinger]

bu44er, will need to keep a check on that then , I do know they are OK atm however

[lexi]

Does the Xanty have an ally caliper? I have only ever changed the pads mind you on my previous models.
On the C5. Why did Citroen put a 2 part locking compound into caliper bolt holes? Was it to fill the gap as the reamed caliper holes are bigger than bolt dia? This would tighten the whole thing up and stop the caliper just relying on head of bolt. I find it hard to believe it was just to stop galvanic corrosion. The zinc coated bolt would have done that. Nope...........it's a bloomer I think.

[Hell Razor5543]

When I get around to doing the rear brakes on my C5, I intend to put some baking parchment between the calliper and the trailing arm. With luck this should act as a thin gasket between the two, but be able to handle any heat generated.

[lexi]

That'll do it James.

[citroenxm]

Yes xantia calipers are alloy and alloy corrode they do which is what pushes the caliper out... the arm mounting face itself doesnt get harmed!!

As said only XM DO Not suffer from it ... xantia c5 and I think bx do it..

the C5 can and does cause the most damage because there is even less clearence between caliper and disk the caliper if left can take the disk out on the back so it cant be seen. Ive seen this on a c5.. though I have not on a xantia.. so its even more critical.

I don't think there is enough clearence to fit a spacer or insulating spacer to prevent it.

[lexi]

I don't think there is enough clearence to fit a spacer or insulating spacer to prevent it.

Yes.
Only James's baking paper or my paint would work. Even with piston pushed right in, there is only just enough room to get the brake pad and shim into that space. It is an interference fit.

[Xantidote]

All I did a few years ago when I encountered the corrosion build up on my Xantia's caliper interface (before FCF existed I expect), was to clean off the white oxidation and smear the caliper face and the mating face on the trailing arm with copaslip grease. Not had to revisit to redo