Sticky BX brakes

yangreen · Post by **yangreen** » 28 Nov 2005, 08:59

Hi

When I pull my new BX 16 valve to a halt, even on a hill, the car stays put when I release the pedal. It's very like the hill start assist in smarts!

I'm guessing it isn't designed like that - front wheels felt warm when I parked up this morning. Is this just sticky calipers or something similar?

The brakes never seem to release cleanly even at speed so something is sticky!

Ian

Mandrake · Post by **Mandrake** » 28 Nov 2005, 09:08

That sounds bad!

Overheating the brakes by having them dragging all the time can do serious damage.

The hand brake operates on the front brakes on (nearly) all Citroen's so the first thing I'd be doing is checking the handbrake cables are adjusted properly with the required amount of cable slack, and that the sheath of the cables isn't worn through. (someone with a BX will be able to tell you how/what/where)

I'm not sure if the calipers in the BX work the same way as the Xantia, but on the Xantia they're self adjusting where you turn the pistons to push them in, and applying the footbrake moves them out and operates a ratchet inside the piston.

If you're VERY unlucky you can end up with the piston turned exactly to a point that will cause binding of the brake when it clicks over the next ratchet step.

This happened to me once when I was fitting new front pads and it took me a while to figure out why the brake was suddenly locked up solid even though the handbrake was off. Finally I managed to turn the piston half a turn and the self-adjuster sorted itself out.

Regards,
Simon

bxbodger · Post by **bxbodger** » 28 Nov 2005, 09:12

Apart from what Mandrake has said,look andfeel to see If the discs have a pronounced wear lip on them- if so the pads won't release properly and will cause the symptoms you describe.

Mandrake · Post by **Mandrake** » 28 Nov 2005, 09:18

If the lip on the edge of the discs is not too bad you can usually save a new pair of discs by simply chamfering the edge of the pads a little bit so the lip doesn't touch. Provided that the main swept area is flat of course.

I had to do that on mine especially at the front as without it the lip would hold the pad away from the surface and reduce the initial application sensitivity of the brakes considerably.

A little bit of chamfer on the short sides of the pad also usually prevents the brakes squealing and/or creaking/groaning under load which the Xantia brakes seem to be a little bit prone too especially on an automatic.

Regards,
Simon

jeremy · Post by **jeremy** » 28 Nov 2005, 14:54

Slow release of the brakes is often a sign of air in the hydraulics. Citroebics first then if necessary bleed the individual limbs.

Its also possible the pistons or caliper slides are not moving freely especially if the car has been standing for a while.

AndersDK · Post by **AndersDK** » 28 Nov 2005, 16:27

Guys -

Remember : The BX has the HI-pressure brakes system. Meaning the brake calipers have a direct unrestricted pressure relieve path to the reservoir - WHEN the pedal is left untouched.
No matter how much air may be trapped there - it will never cause brakes to drag - as it will be vented back.
Air will cause the very scary and characteristic symptom : a DELAY from pressing the pedal to the braking comences.
Also any ABS system can never cause this as all this system does - is REMOVING brake pressure when it is supposed to.
All HI-pressure brakes Citroen models works this way

As a consequence - check the pedal is not slightly activated causing the brakes to drag. Especially on RHD export models with that silly extension rod between pedal and brake doseur valve. Dirt & rust in this extender guide may cause the rod to drag and permanently activate the brakes.

Its very easy to check : engine idle, handbrakes on, dont touch brake pedal.
Now check for flow in the 2 return path lines (joined at reservoir) from the doseur valve. There should be none.

yangreen · Post by **yangreen** » 28 Nov 2005, 18:49

Thanks Anders. Were it not so bloomin' cold and snowy (I know, us Brits are terrible when it snows!) I'd be out there checking!

Certainly you barely have to touch the brake pedal to get brakes but that's just typical hydro-Cit I think.

I'll check it out at the weekend and revert to my Audi for the remainder of the week before it is taken away (hoorah!).

Ian

citronut · Post by **citronut** » 28 Nov 2005, 19:57

the most common causes for BX,XANTIA brakes draging is cracked hand brake cables or the hand brake lever on the calipper not comming off completly,and the cables crack where they are flexed every time you turn the steering,they do not wear through unless they are touching the wheel rim
regards malcolm

yangreen · Post by **yangreen** » 28 Nov 2005, 21:47

Well for info, the handbrake has a frightening amount of travel in it - could this be linked?

I'm getting a low pad warning light now too though which is very odd as apparently new discs and pads were fitted not long ago.

Too bloomin' cold to get the car up and get a wheel off though! Will check at the weekend.

Ian

citronut · Post by **citronut** » 28 Nov 2005, 22:49

the way to adjust your hand brake travel is with the car on level ground hand brake off engine running press hard on the brake pedel 2 to 3 times,if this dose not work it might be your pads are worn down or the lever on the caliper is not returning off completly
regards malcolm

jeremy · Post by **jeremy** » 29 Nov 2005, 07:54

Brake pad warning probably meand that the sensor wires have got caught up in the handbrake linkage and have rubbed off the insulation Mine had green copper stains on the handbrake lever on the caliper!

yangreen · Post by **yangreen** » 29 Nov 2005, 13:45

Just to prove I know nothing about BXs yet, does it have separate handbrake pads (like a 2CV) or does the handbrake just work on the normal pads?

Flashing light and loads of handbrake travel does sort of suggest pads have had it but I'll have a look at the weekend. Will try the adjusting trick when I get home (in the AX today).

Ian

jeremy · Post by **jeremy** » 29 Nov 2005, 13:54

Handbrake is on the front and the thing has a single piston sliding caliper. which incorporates the handbrake which works on the same pads. Brakes are the same as all other BX except for vented discs on the front of the 16 valves only (caliper is the same but with a wider bridge). All BX pads are the same. - strange but true!

Pads are removed by sliding out the metal strip at the top (if you're lucky). The piston has to be screwed back and the piston must be in the correct rotational position. Pad with pip on the back fits this piston.

bxbodger · Post by **bxbodger** » 29 Nov 2005, 13:57

The handbrake works on the front pads- theres a lever on top of the caliper that operates a cam behind the piston.

You must have the last BX in the world with a pad wear warning system that still works!!! Most just get the wires cut off to stop spurious signals caused as Jeremy says above.

Do the pads unstick themselves if you reverse a short way??

yangreen · Post by **yangreen** » 29 Nov 2005, 14:30

Good question and one I can't answer until I get home!

Pad warning could be spurious - milder weather due so may get a chance to have a butchers before the weekend.

Will also try the handbrake adjustment trick.

Ian