xantia brake issues

[chinkostu]

So since replacing the bearing and balljoint on the passenger side i've got a rather alarming issue, you get really odd braking almost as if the brakes are releasing and reapplying slowly, which makes slowing to a stop rather sketchy!

I thought it would have been the abs sensor or ring packing up so removed the ABS fuses (theres 2??) but have the same issue. theres no leaks of lhm anywhere, have replaced the accumulator sphere correctly as well as that seems to cause the same issue but still no luck.

Before I end up firing into the back of a lorry where should I be looking? Is it worth bleeding the brakes, although I can't personally see it helping as they're dead ends and what i've done shouldn't have introduced air in!

[Hell Razor5543]

I would bleed the brakes just to make sure that is not the problem (and for peace of mind), especially after replacing ANY hydraulic component. However, I wonder is the handbrake might not be releasing cleanly (possibly the cable has become a bit bent when the work was done), so it might be 'applying' a bit of friction all of the time, and when you brake you are getting the extra 'input' from the handbrake.

[sparksie]

Check the brake disc runout on the side you did the bearing on.
Best to do it soon, because if it's out of tolerance, you'll quickly damage the disc.
I expect you'll find it has quite a wobble and, if I'm right, you'll need to take the disc off and thoroughly clean the face of the hub and the mating surface on the disc. You can't be too meticulous with this! Even a flake of rust is too much.
While you have it off, inspect it carefully for any uneven discolouration, or odd wear patterns.
I can't recall the Xantia setup, but on some cars the disc can be fitted in more than one orientation. If, after a good cleanup and passing inspection, it still has excessive runout, trying it in a different orientation might help.
If the discs are running true and the braking feels on-off-on when you try it, you need to revisit the work you carried out. You may have left something loose, allowing the wheel to oscillate back and forth in the arch, though this is a bit of a stretch. For you to feel it, under braking, it would need to be bad enough to affect the handling under other conditions too.

[chinkostu]

Thanks guys, waiting for a good day to check! I should add I tried slowing on just the handbrake and had the same effect, but letting the car coast normally out of gear didnt so something mechanically isn't happy!

[sparksie]

Hi Stu
Yes, on a Xantia the handbrake works on the front discs, so the effect is the same.
It will appear as brake ovality, in a MOT rolling road test.
The trouble with leaving it is, over a surprisingly short distance the "high" points will be worn down by the constant rubbing on the pads and you'll end up with a problem you can't fix and have to buy new discs. If the disc is damaged, always replace both discs on the same axle at the same time.
Make sure to observe scrupulous cleanliness when doing this, particularly on the hub face and the mating surface of the disc

[chinkostu]

Hi Stu
Yes, on a Xantia the handbrake works on the front discs, so the effect is the same.
It will appear as brake ovality, in a MOT rolling road test.
The trouble with leaving it is, over a surprisingly short distance the "high" points will be worn down by the constant rubbing on the pads and you'll end up with a problem you can't fix and have to buy new discs. If the disc is damaged, always replace both discs on the same axle at the same time.
Make sure to observe scrupulous cleanliness when doing this, particularly on the hub face and the mating surface of the disc

It was more a check to see if it was something hydraulicly wrong as the handbrake is mechanical. Don't worry, i know its on the front

Its the baffling part that it happened after working on the car.

[sparksie]

I'd say you got unlucky and caught a bit of grit between the hub and the disc, when you were putting it back together.
It's very easy to do. Almost guaranteed to happen, unless you actively prevent it.
A good go over with a wire brush, followed by a soft cloth, just before putting the disc on, is all it takes, but if you don't know..!
I sympathise with you, working outdoors.
Thanks to a spectacular failure to plan (most unlike me, it has to be said), I've been in a similar position for several months. It was fine, even pleasant, during the Autumn, but it's no fun in the Winter.

[chinkostu]

Update

Had the wheel off and pads out, there was a lot of crud i've cleaned off the ears of the pads and related areas on the caliper, when rebuilding i noticed the disc was hard to turn so swing back up and wound caliper in a few turns. seated pads and readjusted handbrake using footbrake and is now free to turn but can hear it drag slightly when turning.

I'm gonna assume I mucked up and the handbrake was dragging slightly, and possibly left some material on the disc. Can't be sure until tomorrow when i've the time to take the carrier and disc off!

[chinkostu]

Think i've got to the bottom of it after taking the disc off and being greeted with this



Safe to say they've cooked. My thinking is human error as i was rushing to finish before darkness hit, so likely missed the pad dragging (handbrake sticking i assume) so it's ruined the disc. Inboard pad is thinner as well, so looks like a new set of discs and pads are in order again