Rear Disc Retaining Screw

[paul001]

The rear Disc retaining screw should it be a round post type thing or should it be a Phillips like the front ?

I went to change the rear ones today and came across this retaining screw, looks like someone in the past has been a touch brutal so I would like pointers on how to remove it without drilling it out

[ken newbold]

It's supposed to be something like a stud which helps when hanging the rear wheels, unless you have alloys.

I've usually undone them with a good pair of mole grips.

[prm]

You could try placing four large nuts/stack of washers/spacers, over the wheel bolts and retighten to take the pressure of the screw or pin.

Whack the head with a flat punch, plenty of WD40, whack again, then try a small chisel to loosen, if very little remains of the head.


Regards

[paul001]

Tried the Bolts to take the pressure off but it seems someone has gone a touch over kill on tightness of the stud and I have cleaned all the gunge off finding it is a shouldered stud too tight for mole grips so would like to know does anyone know if it is 5mm or 6mm? I measure it at around 6mm ish

[paul001]

Got both disc retaining bolts out they turned out to be 7/32 [5.56mm] changed the discs just one small issue the back calipers are two part calipers and I cannot get the necessary Seals from Citroen, anyone have a suggestion would the existing seals be ok if I don't touch them just simply replace the caliper halves then tighten everything up? If they start to leak I will have to review it

[jonathan_dyane]

Too late alas, but having removed the pads you are supposed to use the pad retaining bolt to hold the caliper together after you unbolt it. That said, odds are if you ensured that the faces were clean, you will get away without replacing the seals; you'll just have to monitor the situation and see if there is any seepage.

Why can't you get new seals from Citroen?

You might find that the next problem is the bleed nipple refusing to undo; before it is rounded I suggest using heat and a tight-fitting socket. Should this and hammering on a smaller socket fail, the next step is to weld on a nut that fits over the bleed screw, and try to undo it before it cools. Do go easy though, the nipples are easily sheared off...

[paul001]

There was no retaining screw in the side pads were just being gripped from the pressure of the pistons onto the disc didnt attempt the otherside till I got some advice

[DavidRutherford]

Got both disc retaining bolts out they turned out to be 7/32 [5.56mm]

In which case they were moderately corroded! Everything on a BX is metric.

[DLM]

In which case they were moderately corroded! Everything on a BX is metric.

At which point, if working with the original parts, it' s a case of renewing them if at all possible. - particularly in the case of the rear brake/wheel area, where there's plenty that corrodes and seizes to cause problems unless given regular attention (particularly the pad cover bolt and and bleed screw).

This area needs to be treated as a system rather than individual parts - one bolt, bleed screw, caliper inner or brake pipe union left to fester can make life very difficult later.

The Citroen part no. for the retaining stud part is 96 202 546 - described as disc fix screw diam 6x100 on the (quite possibly outdated ) BX parts PDF that's been online a long time.

A cover for the rear pads is very desirable, otherwise road muck mixes with the pad residues. If all else fails, there's scope for constructing a home-made cover out of sheet metal. as the originals, if available, do corrode away. The retaining bolt for the rear pads cover is, I'm sure, still available, or you can find/modify appropriate bolts to fit. I've had to do this before. Even if the original pads still have life, remove them and clean out the area thoroughly - this is essential for long caliper life and free movement of all parts. This works wonders sometimes on reluctant rear brakes.

If worried about putting undue pressure on the seals when pushing back a caliper cylinder in a caliper on car scenario (if stuck or if renewing pads) provide local pressure relief through unscrewing the bleed screw slightly (assuming no big problems here).

If the caliper's been removed , stuck cylinders can be pushed out with the aid of a basic air foot pump or similar (don't forget they'll shoot out if unrestrained). They too benefit from careful cleaning (no abrasives), and you'll get a good chance to see the state of the caliper seals. The sudden "kick effect" proved more effective than a compressor air line the last time I did this.

Apologies for banging on about this... but I've ended up having to do a lot of remedial work in this are on some BXs and benefitted greatly from taking other people's advice and adopting their methods (thank you Tom and others!).

[paul001]

Thanks for the advice!! Job has been done. Heat wasn't needed infact the bleed screws slowly came undone took around 10 mins of gentle tapping and releasing spray on each just same as the front the bleed screws have been chewed and rung badly so waiting for replacements for the next time I need to touch the brakes though for now I'm happy that the brakes are replaced. Full Discs and pads all round have been done due to corrosion on the backs of the disc faces.

Now a very happy Citroen BX GTi driver

[DLM]

....and I'd imagine the difference is very noticeable. A full brake service really shows how good the BX brakes are.

[paul001]

Never really had a problem with the brakes it was on changing a rear tyre that I noticed the discs had rusted out and the pads werent doing anything

Next stage is to look at the front strutts as they are jumpy going up from position 2 to position 3