Changing front brake flexis

[MULLEY]

Try driving your car without using the handbrake at all

What, like most people on the roads it seems? Oh, sorry - this isn't the grumpy old git thread.

[Dollywobbler]

Today's experiment. Drove 25 miles this morning. No heat build up. Then drove 10 miles to the office. Very slight heat build up. Drive home, despite not attacking bends with my usual verve, can't touch the wheel nuts.

I'm increasingly feeling that it's a footbrake thing. At one point this morning, I came to a stop at a junction. Took my foot off the brake, car held, then after a few seconds, started to roll backwards. That'd support the knackered hose theory.

I've got no chance of getting it done before the weekend though, so I guess I'll be at La Vie en Bleu in either the 2CV or Renault 21.

[MULLEY]

Apologies for sounding dim, but doesnt the brake hose just hold the brake fluid? unless its actually leaking & reducing the pressure, it wouldn't affect anything that you've mentioned?

I still think its buggered caliper(s), even if they've been freed off, they can become sticky again quite quickly once the sliders have pitted etc....

[docchevron]

It's not unknown for flexi's to fail internally and act like a one way valve allowing fluid in but not out, or vice versa, so it could be the flexi..

[Stinkwheel]

As Doc says, do flexis first, just so easy to do, its worth the try.

Aside from that, im thinking xantia calipers to bolt on? or usual re-con route with yours Ian??

[DavidRutherford]

I came to a stop at a junction. Took my foot off the brake, car held, then after a few seconds, started to roll backwards. That'd support the knackered hose theory.

Whilst I'm beginning to lean towards the knackered hose theory, what you've experienced there is the same as happens on all fully powered braked citroens. The slight delay in the brake releasing is the fluid returning through the Dosieur valve to allow the pads to retract from the disc. My CX does this reliably every single stop, and has no problems at all with brake drag. (actually, it does it even more than the BX, as the BX has two front brake pistons, the CX has eight.) The handbrake is also completely independent on the CX, so it's not related to that either.

Now, if you were to take your foot of the brake and the car doesn't then start to roll, you have your problem.

Here's a quick check to do: When you release the handbrake, are the handbrake levers on the calipers reliably dropping back to their "off" position? The springing in the back of the caliper can partly sieze quite easily, as any road wash getting under the big rubber cover will cause it to bind up. I've seen a number of calipers suffer from this.

[Dollywobbler]

Well, I've had a wheel off this evening. Pulled out the pads on one side and lo and behold, the disc is still fairly reluctant to turn. Now, I expect some resistance from the transmission, but perhaps this is the source of the 'sticky' feeling at very low speeds.

I did check the handbrake release, and even with a gentle release of the lever, the handbrake does seem to be coming off fully.

This leads to hypothesis two (version 245) that actually, the brakes are just getting very hot because when I get home, I've just come cross-country on small roads, and so have been using the brakes extensively. After all, the front brakes on a BX aren't exactly well ventilated are they? Yet my Renault 21 driven with similar gusto doesn't get hot brakes.

Annoyingly, it then started raining, so I'm only halfway through refitting the pads. Hopefully it'll stop in a bit...

EDIT - Cancel the above. Further experiments have revealed that application of the footbrake OR the handbrake makes the wheel harder to turn afterwards. So, the brakes are struggling to release which I guess means caliper. Any way of now avoiding fitting brand new calipers? Only checked one side so far. It's raining again now though...

[DavidRutherford]

After all, the front brakes on a BX aren't exactly well ventilated are they?

Actually, with the air scoop fitted to the front of them, they are very well ventilated.

To "recondition" your brake calipers:

Take the pads out. Undo the bolts that retain the pins that the caliper "floats" on, and remove the floating caliper. (leaving just the fixed bit behind) Clean up any corrosion on the pins and in the sliders on the caliper, making sure you leave a fairly smooth surface (600-1000 grit is fine)

Liberally grease sliding pins and sliders, re-assemble and ensure all rubber boots are in place to prevent road wash ingress (the little concertina bellows are known for splitting after a while. The can be replaced,as they are just a push-fit into the caliper)

... and enjoy less rolling resistance.

[Dollywobbler]

Thanks David. It's odd. My Citroen man is adamant that the calipers are fine, but I don't see how they can be. If it was the flexis, I would have thought that operating the handbrake would not cause the brakes to stick slightly.

[Dollywobbler]

Well, yet another SWING on the WTF is wrong with the car. We're back at paranoia this evening. I had a nice blat home in the Renault 21 this evening and guess what! Hot brakes. Perhaps it's just my driving style then...