zx brakes

chris74zx · Post by **chris74zx** » 07 Mar 2006, 21:14

hi all, my '94 zx volcane just failed its test on (amongst other things), low pressure and poor handbrake right rear brake, thing is i don't know exactly whats wrong with it, the caliper seems ok and releases ok and the piston and seals look ok, it comes on and off properly it just doesn't work well enough, i've noticed two pressure regulating vavles underneath, could these be a problem?, as the handbrake on that side is also poor i was thinking discs and pads were more likely, have already tried cleaning these up but didn't make much difference, anyone have any similar experiences with these? will disc's and pads be enough tho solve the problem?
cheers.

jeremy · Post by **jeremy** » 07 Mar 2006, 21:44

I agree with you - the fact the handbrake is bad as well would suggest that the hydraulics etc are ok and that the fault must lie in the caliper.

These calipers are similar to those used on the front on BX and Xantia as well as ZX (but without the handbrake) and all are prone to the sliders sticking. This may be worse on the back of a ZX as its possible that the brake seldom operates when being driven. try taking the pads out and see if it slides freely, and with no play. Examine the slider bar which should be shiny. push it around a bit and then re-assemble. You may be able to get some lubricant under the boots if they are still there which will be beneficial.

The other possibility is that there is corrosion between the caliper and its mount - which on other models can cause considerable problems. If this is the case, clean it off carefully and thoroughly, grease the surfaces and re-assemble.

8304 · Post by **8304** » 08 Mar 2006, 08:19

its easy enough to check the discs and pads - take the wheel off and have a look. If there is plenty or meat on the pads they will not be the problem and run your fingernail up the disc to the rim - if there is no lip the disc should be ok providing its not warped etc which is unlikely.

My money is on either the sliders - ive had trouble with them on each corner of my zx or a sticking / siezed caliper. I dont think it will be pads / discs especially if there is no bad noises like metal on metal coming from the back.

The thing is with sliders they tend to make the brake drag if they are seized as the hydraulics push the pads on and then they do not return properly becuase the disc cannot push them back so my money is on the piston starting to sieze in the caliper....

good luck!!

shezads · Post by **shezads** » 08 Mar 2006, 11:37

I've got the same problem on my 94 volcane td. Same side too.
The slider - is that the piston or is that the top of the caliper where the brake pad sits, getting rusty. Which part to clean up?

Thanks.

shezads · Post by **shezads** » 08 Mar 2006, 11:40

I've got the same problem on my 94 volcane td. Same side too.
The slider - is that the piston or is that the top of the caliper where the brake pad sits, getting rusty. Which part to clean up?

Thanks.

citronut · Post by **citronut** » 08 Mar 2006, 13:55

the usual thing if some one has put new pads in and just leaverd the piston back insted of whinding it back in,this will damage the adjuster inside the caliper,then it just wont adjust up,also if the arm on top of the caliper is not coming right off when the hand brake is releasted the adjusters will not adjust up,try disconecting the cable at the caliper making sure the lever is fully off,then start the engine and press on the brake peddle hard 2-3 times,now refit the cable,when you let the hand brake off the lever should come right back
regards malcolm

jeremy · Post by **jeremy** » 08 Mar 2006, 16:55

Malcolm - I agree that if the piston is levered back rather than being wound back on pad change the handbrake mechanism will be damaged and the handbrake will not function properly. However wouldn't the footbrake still work properly?

Chris - another strange possibility might arise if the brake has been fitted with new pads but not a new disc. Some pads are a different shape to others and it may be that an edge of the pad rubs on a rusted area of the disc that was not previously used. As its raised in reality the rest of the pad doesn't make proper contact and the brake is feeble.

I had this on the front of our ZX when I got it - put in new pads and the brakes while legal where poor - and smelt wonderful at first. New discs and pads cured it and it was easy to see that the Delphi pads I'd fitted had been rubbing on the rust near the centre of the disc - So I'd wasted the cost of pads and discs as cutting off the additional bit of pad with chisel would have probably cured it!

chris74zx · Post by **chris74zx** » 08 Mar 2006, 17:17

thanks for all the thoughts guys, interesting stuff about the caliper - only problem is its not sticking at all, it comes off as soon as you release the pedal/handbrake, is this still the likely cause?, i know its had a few disc's and pads in its time but they've been fitted properley by the previous owner (my brother), and i know it was done correctley with new pads and disc's, i'm kind of stumped as to which bits to get as none of them are obviously at fault, i've had the caliper apart on a previous occasion and seals/piston looked and moved ok...

citronut · Post by **citronut** » 09 Mar 2006, 09:00

Jeremy i agree with what you said,if i fit pads to a customers car and it has got a rusty band on one or bothe edges of the disc,and customer dose not want to have new discs fitted yet,i just grind a slight bevel on the edge of the pads,but also if the caliper is not adustting up properly it might not respond as quick as the other side on first press of the pedle,so it would appear to be low on efort
regards malcolm

citronut · Post by **citronut** » 09 Mar 2006, 09:08

ps,
how dose the pedle feel,is it firm right to the top,if not maybe you have air in that side rear of the system,as this would give a week foot brake pressure and posibly it would not adjust the hand brake mechanisum up properly because the piston is not comming out to the full amount of travel
regards malcolm

chris74zx · Post by **chris74zx** » 09 Mar 2006, 19:40

the pedal feels ok, i wouldn't say its that firm at the top of its travel, to be honest i've never been that impressed with the brakes, i'm assuming they're all like that, i'm gonna check the sliders at the weekend, it the bleed nipple looks ok then i'll give it a quick bleed as well.

jeremy · Post by **jeremy** » 09 Mar 2006, 20:17

Chris - while you are looking at it - have a very good look at the caliper/trailing arm joint. Some Citroens are prone to corrosion and the caliper doesn't sit straight - which can cause a poor brake performance. This is cured by dismantling and thoroughly cleaning.