Pesky Xantia rear caliper bolts

Post by **RichardW** » 02 Mar 2009, 12:41

I've done 2 hatchbacks before - including the first where the rear brakes were so gummed up I had to cut the pad bolt and drift the remains out of the caliper, and saw one of the brake pads in half to free it from the caliper - and not had that much trouble with getting the bolts out. But, I set off to tackle the estate on Saturday and the bolts were not playing the game. They were v tight and the first top one started to round off. Not wanting to leave it stranded I gave up and put it back together, with the pads well greased, which should get me through the MOT. I will have to do the calipers though in the near future. I reckon a six sided impact socket will help, but is whacking them with a windy gun a good idea - or is this likely to leave me reaching for the MIG to weld nuts on the now broken off remains of the bolts? Or should I just cut the heads off, extract the caliper and disc together and then work on the bolts with a pair of stilsons or similar?

On the up side, the bleed screw and pipe slackened on the N/S with a gentle tap of the hand on my small 8mm spanner

citronut · Post by **citronut** » 02 Mar 2009, 13:10

i would not use a windy gun as you dont get the same feel as you do with a hand job, woooooops, but certaily use a 17mm hex or side wall drive socket, i try not to ever use multi point socket for this very reason,

sometimes a sharp blow squre on the head of the bolt will help,

also when these bolts are that tight it's usualy because of the corosion biult up in the calipper were the bolt passes through it, although you could try cleannning up any thread werte it protrudes at the inside face of the arm, and maybe give that a little heat

regards malcolm

lexi · Post by **lexi** » 02 Mar 2009, 17:07

If you weld a nut on it now the heat may loosen it. I use Oxy/Acy with a small torch for this. Pencil flame localalised always does the trick.

I`ll be going in there myself as I can hear N/S Caliper binding.

Post by **CitroJim** » 02 Mar 2009, 17:21

citronut wrote:although you could try cleannning up any thread werte it protrudes at the inside face of the arm, and maybe give that a little heat

Works for me

Clean the exposed threads with a wire brush and then douse in Plus-Gas (not WD40) and leave it to soak in for an hours or so.

Then, in full agreement with Malcolm here, attack with a hex socket and gentle force on a long breaker bar.

fred1 · Post by **fred1** » 02 Mar 2009, 20:02

Hi,

The C5 uses a similar calliper. However, Citroen have "improved" the design by adding two small holes, one at front and one at back of each bolt and use these to "flood" bolts in calliper with loctite. They also coat back of calliper.

Have they fitted this type to your Xant ?

The effect of this is that the aluminium callipers continue to react with steel radius arm and corrode plus the bolts are now virtually un-removable !!

Many people have had them shear.

Best bet is to release disc retainer screw and undo bolts a bit each in turn allowing the calliper jack off the radius are bringing the disc with it while leaving the bolts in the calliper. You will need to undo the brake pipe as well.

Once off the car you can try winding/knocking the bolts out and then clean up the holes with a drill. You can then refit with new bolts but no loctite !!!

As corrosion caused by electrochemical cell formed by dissimilar metals in presence of water I suggest you replace calliper with a gasket of thick polythene sheet between calliper and radius arm to disrupt the electrical contact. This seems much more effective/reliable than trying to keep out water by means of grease (or loctite!).

My C5 has now done 40k with this in place and shows no sign of corrosion whereas previously with use of just grease it had.

Good luck with the bolts I had to use a large torque wrench and a lot of patience to "work" the bolts back and forward, gaining a bit on each cycle.

New bolts are surprisingly cheap at about £2 each from a main agent . I took note that my local one seemed to keep a large quantity in stock !!

Regards

John

Post by **RichardW** » 02 Mar 2009, 22:58

Some interesting thoughts, most of which I have covered. Cleaned up, Plus Gas at the back, tapped with hammer. But they were not for moving - I didn't get much heat on as I worried about the ABS cable - more required I think. Interesting that Malcolm mentions 17mm as this is the size I reached for - as iI am sure that is what size they were previous (I have a rediculous memory for things like that

) but these are 16 - and that is part of the problem I think - I only have a deep 16mm socket, and that plus a 3/8 / 1/2 drive converter makes for quite a bending moment on the socket. Off to get myself a decent set of flank drive sockets

Interesting news about the C5s John - this is a late 2000 car, so it's possible it's fitted with some C5 esq fitments (although not the same given the LHM difference!). They were different to the ones I have seen previously but then I've never looked at an estate before!

More when I get them off

steelcityuk · Post by **steelcityuk** » 03 Mar 2009, 00:11

Would a good 'dab' with a decent mig welder on the bolt head provide enough heat to free things off? Another possibility could be the freezer type penetrating spray though from what you say I doubt there is an easy way to do this job.

Good luck with it.

Steve.

reblack68 · Post by **reblack68** » 03 Mar 2009, 07:22

Estate bolts are longer than the saloon ones and are M10 instead of M9.

After the last time on my car I vowed never to attempt the job again unless I was armed with a full set of spare bolts. Three of mine broke and all of them were bent.

The build up of corrosion makes removal difficult in two extra ways. It puts more tension on the bolts and it causes the bolts to bend. I think it's that, rather than the thread being tight, that makes them break.

fred1 · Post by **fred1** » 03 Mar 2009, 08:38

Hi,

Looks to me like the "bent" bolt scenario is the most likely.

However, the "jacking2 off method I used for the C5 should work as it leaves the bolts in the same place in the calliper. The degree of bend will not be large and they should rotate ok within the calliper and as you are not trying to draw the bend out through the length of the hole they should not tighten up. I think it is this latter aspect that causes the problems.

Regards

John

Post by **RichardW** » 03 Mar 2009, 12:32

Ah joy.... Looks like it was good that I stopped where I did, rather than getting stuck with broken bolts. How did you get the remains of the old bolts out Richard - was there enough left to get stilsons on them or something, or did you have to drill out and use a stud extractor?

In fact, if they're going to be a git, it might be better just to wade in with the angle grinder, lop the heads off, free the caliper, then at least there will be an unloaded long stud to go at. Of course, if the caliper decides it won't come off over the studs

Looking forward to the job now

citronut · Post by **citronut** » 03 Mar 2009, 13:45

dont worry unduely Richard,

just attac it in the corect manner first firm but gently with not to longer bar, or then you are more likely to shear them off,

all the years i have been working on citroens, i think i have only ever had one calliper bolt shear off on me,

and that had welded it's self to the calliper with corosion

regards malcolm

reblack68 · Post by **reblack68** » 03 Mar 2009, 18:27

RichardW wrote:Ah joy.... Looks like it was good that I stopped where I did, rather than getting stuck with broken bolts. How did you get the remains of the old bolts out Richard - was there enough left to get stilsons on them or something, or did you have to drill out and use a stud extractor?

In fact, if they're going to be a git, it might be better just to wade in with the angle grinder, lop the heads off, free the caliper, then at least there will be an unloaded long stud to go at. Of course, if the caliper decides it won't come off over the studs

Looking forward to the job now

One bolt broke proud, one flush and one sub-flush. My friend used the Mig to add enough length to weld nuts onto them, then I worked with the spanner until the nuts came off- at which point he came over and welded them again. The whole area heated up with each weld, which helped matters a bit. It wasn't fun but it wasn't unduly difficult either.

This was in the hatch though, which has slightly thinner bolts.

If I ever do it again I will definitely have new bolts available and I will seriously consider grinding the heads off and using vice grips.

Post by **RichardW** » 02 Apr 2011, 20:55

Blimey, was that 2 years ago? Still haven't done the job, but as I went to the dealer to get the gaiter for the inner track rod joint, thought I would get some bolts as well - car is now on 115k, and I suspect original rear pads, so I really must do the job this year - fitted a new tyre to the NSR today, and the caliper is well askew! But, the bolts are nearly 3 quid EACH!! At least some of them had better have the decency to snap off

dnsey · Post by **dnsey** » 03 Apr 2011, 08:04

Is it necessary to use genuine Citroen bolts? I'm sure they don't make them specially!
Presumably, any appropriately-sized high tensile bolts would be OK.

Xantidote · Post by **Xantidote** » 03 Apr 2011, 11:15

IIRC, the rear caliper bolts on my Xantia only have the end part threaded, for where it fits into the arm.

Ou of choice, I'd be unwilling to use any substitute bolt if it had much threaded part within the caliper body itself, as there's enough of a problem with corrosion between bolt & caliper as it is. I think having the possible addition of gunged up threads within the caliper would only make extraction of the bolts even more difficult