Nearside front Brake Problem I Believe ??

steviewonder7 · Post by **steviewonder7** » 17 Jan 2006, 20:03

Hi Folks,

Once again I'm in need of some of your wisdom.
A little while ago I renewed the brake pads on the front of the vehicle,both sides of course,mainly because the 'inside' pad of the nearside caliper was badly worn down compared to its brother in the same caliper.There was about 3mm of the old stopping block left to rub against the brake disc compared to about 6mm on the other pad (in the same caliper).Its like the caliper piston acting on the worn out brake pad is 'stuck' in the operated position.
I also noticed when driving slowly that there was the old 'squeeling' sound typical of brake disc squeel eminating from the front nearside suspension area(enough for any pedestrian to turn their head around an look to see where this noise was coming from).
Now I said to myself that I had a sticking caliper,but upon inspection when renewing said brake pads I could not really find anything wrong with the caliper.I didnt have anyone available to press the brake pedal while I observed the caliper piston movement.
Anyway I had a spare recon caliper and therefore fitted it with the new brake pads and bled the brakes.
Today I noticed the 'squeel' was back and I'm at a loss at what to try next.
Anyone with any suggestions please ????
thanks Steve

Mandrake · Post by **Mandrake** » 17 Jan 2006, 21:05

Only one suggestion there, are you completely certain the squeal is coming from the front brakes and not the rear brakes ? It can sometimes be very hard to tell, especially if you're on the opposite corner of the car.

And the rear brakes have a tendency to squeal on the Xantia... mine has started doing it again too....

I may have the dreaded rust build up under the caliper mounting problem that everyone talks about, but havn't had time to look at it...

Also uneven wear on the front pads is apparently semi-normal on the Xantia from what I've read here.

Mine is the same too - when I replaced the front pads, of each pair, one was only half the thickness of the other, (can't remember which way around it was) despite the fact that everything seems in order and the caliper is perfectly free to slide.

I think it must just be poor design of the caliper. (My guess is its something to do with the fact that there is only one caliper slide bearing where most cars have two, causing it to not slide freely when under the strain of braking)

Regards,
Simon

Post by **Peter.N.** » 17 Jan 2006, 21:06

The 'squeal' is not neccesarally associated with excessive wear, in fact with drum brakes, squealing was usually an indication that they were working well! Check to see if there is any excessive wear, if not its just a case of the pads oscillating for some reason. There used to be 'anti squeal' shims fitted at one time, I dont know why they dont normally squeal now but if the wear is OK I wouldn't worry about it.

steviewonder7 · Post by **steviewonder7** » 17 Jan 2006, 22:13

Thanks for your reply's Peter and simon.

I'm not one hundred percent certain the 'squeal' is resident at the front nearside caliper.My other half who has better hearing than me seems to think the 'squeal' is also eminating from the same caliper as I do.
If the unevenen brake pad wear is as common as you say Simon,then I think thats a very poor design(pity I couldn't transfer some other type of caliper from another make of vehicle over in place of the front pair of mine ?!).
I'll check the rear brake calipers anyway just in case like you say Simon,even though I did check them a few months ago,then they had plenty of wear left on them and the disc's were not rusty at all therefore presumed to be doing their job(brake's that is).
As for leaving the sqealing 'there' and putting up with it.....naa.. bloody annoying to me gets on my nerves.

Kowalski · Post by **Kowalski** » 18 Jan 2006, 10:44

Mandrake wrote: Mine is the same too - when I replaced the front pads, of each pair, one was only half the thickness of the other, (can't remember which way around it was) despite the fact that everything seems in order and the caliper is perfectly free to slide.

I think it must just be poor design of the caliper. (My guess is its something to do with the fact that there is only one caliper slide bearing where most cars have two, causing it to not slide freely when under the strain of braking)

I've just done the front brake pads on my car and I had one set of pads that hadn't worn symetrically, but the other pair had. The left hand side front brakes had been making a bit of noise as they do when the caliper slide gets sticky, so I lubed it up and that has improved the noise.

The caliper slides can feel completely free when they've got no braking load on them but it only takes a little bit of friction to lock them up solid or to stop them from floating freely. My calipers felt free before I lubed them despite the fact that they werent, its difficult to tell how free they are by hand because of the friction from the rubber boots. I am a bit pedantic about keeping the caliper slides in good condition which may explain why my pads generally have worn symetrically apart from this one set. I'd agree that its not the best of designs in some ways, every other single piston fully floating caliper seems to have 2 slide pins. With most other floated calipers you need to undo bolts to remove the brake pads which means you can get dirt into the slides, where as you dont have that problem with the Xantia. My brake pads that I've just replaced lasted 37k miles so I don't think that there is that a big advantage to the Xantia system from an ease of maintenance point of view.

steviewonder7 · Post by **steviewonder7** » 18 Jan 2006, 17:55

Nice to see that I'm not the only one to have adverse wear on their brake pads.
You say you 'Lube' the calipers Kowalski,what form of lubrication do 'you' use on these calipers of yours?
I've never really had to lubricate calipers before.I've given them a good ol clean before and made sure the brake pads are free to move in the caliper.
Thanks for your reply.
Steve

Homer · Post by **Homer** » 18 Jan 2006, 20:21

I've never had a set of front pads (on a BX or Xantia) wear evenly, I put it down to only having one piston. Usually one pad will be down to the metal with plenty left on the other three.

The rears with two pistons are usually better unless you get rust on the inside of the disk.

Kowalski · Post by **Kowalski** » 18 Jan 2006, 20:23

steviewonder7 wrote:You say you 'Lube' the calipers Kowalski,what form of lubrication do 'you' use on these calipers of yours?
I've never really had to lubricate calipers before.I've given them a good ol clean before and made sure the brake pads are free to move in the caliper.

I only lube the top slide, its the one with the rubber boots on either end.

To lubricate the top slide, with the car jacked up and supported appropriately remove the wheel and turn your handbrake on (this is so that the caliper doesn't drop to pieces whilst you're removing its slide pin). The slide pin is a torx headed bolt (something like T50 or T55), you have to remove it. There are two ways I've tried of lubing the pin. I've tried to grease the pin and put it back in but the rubber boots do a good job of removing any grease that you apply to the pin. The second method I discovered more recently was to stick the spout of an oil can into the caliper where the pin came out, pump a little oil in, not too much or it'll run out the other end of the hole. Then you put the slide pin back in, it has a tendency to push the oil out as you push it through so you have to be prepared to clean up the inevitable mess. The pin is supposed to have a threadlocking compound on its threads, so you should get the threads clean and replace the threadlock, and tighten to the torque specified in the Haynes manual.

Post by **xantia_v6** » 18 Jan 2006, 22:18

My Xantia 2L VSX suffered from squealing brakes and unven pad wear. One set of pads I got was a different make (Lucas?) with silicone rubber patches on the back, and they did not seem to squeal.

Once the back brakes started squealing badly, even new pads did not help for long, but a new set of disks did.

My Xantia V6 has the bigger brakes, as used on Activa and HDI, and they have not squealed, and the pad wear is relatively even.

Mandrake · Post by **Mandrake** » 19 Jan 2006, 05:49

Kowalski wrote: I only lube the top slide, its the one with the rubber boots on either end.

To lubricate the top slide, with the car jacked up and supported appropriately remove the wheel and turn your handbrake on (this is so that the caliper doesn't drop to pieces whilst you're removing its slide pin). The slide pin is a torx headed bolt (something like T50 or T55), you have to remove it. There are two ways I've tried of lubing the pin. I've tried to grease the pin and put it back in but the rubber boots do a good job of removing any grease that you apply to the pin. The second method I discovered more recently was to stick the spout of an oil can into the caliper where the pin came out, pump a little oil in, not too much or it'll run out the other end of the hole. Then you put the slide pin back in, it has a tendency to push the oil out as you push it through so you have to be prepared to clean up the inevitable mess. The pin is supposed to have a threadlocking compound on its threads, so you should get the threads clean and replace the threadlock, and tighten to the torque specified in the Haynes manual.

Ah, so it does have a thread locking compound on it.... I was trying to figure out how to lubricate the slide and decided that bolt would have to come off, but it didnt want to budge, so I assumed it would have a thread locking compound on it....

I wonder if it is worth going to the trouble of taking it off and lubricating it now, as its a few months since I put new pads in, and although I had a lot of trouble with poor brake sensitivity when I first got the car it has slowly normalized to the point where they are working very well. (I think its a bit of uneven wear on the discs)

Regards,
Simon

steviewonder7 · Post by **steviewonder7** » 19 Jan 2006, 19:43

Thanks for the 'lubing' tip Kowalski,I'll look into doing my front calipers very soon.
Just a thought without really thinking deeply about it.Would the 'rear' calipers be up to being fitted to the front and do a decent braking job.I know it would take some modification.Would it be feasible??Anyone?

Mandrake · Post by **Mandrake** » 19 Jan 2006, 21:04

Not a chance

Apart from being highly illegal to perform such a modification, the rear calipers are only designed for very small pads, and less than half the brake force of the front ones.

Add to this the lack of anywhere to connect the handbrake, and you can forget about it.

Regards,
Simon

Kowalski · Post by **Kowalski** » 19 Jan 2006, 22:42

Mandrake is dead on with this one, there is no way you'd want to put the rear brakes on the front of the car. The front brakes are large vented discs with pads, they do about 75% of the braking on a Xantia. The rear discs are smaller and solid, and the pads are really pathetic little things if you compare them to the front pads. There's no handbrake attachment on the caliper either.

As for it being illegal, I'm not sure about that in the UK, it would certainly be unwise, bordering on unsafe, your brakes might do one emergency stop from motorway speed but they'd be hot.

steviewonder7 · Post by **steviewonder7** » 20 Jan 2006, 18:37

Like I said 'not really thinking about it deeply'.I forgot the handbrake operated the front calipers and as you say the pads from the rear calipers wouldnt be up to it anyway..too small and likely to overheat.Pity you couldn't water cool them eh?Anyway it was just a distant thought.