Russ's 2.1 SED Auto now in Mandarin

[Dieselman]

Hi russ

On the brake binding issue check the pips on the back of the front pads.
They must be fitted piston side.
They work the parking brake auto adjust.
Fit one pair the wrong way round and the brake starts to bind, takes a while to get bad though.
If both are the wrong way round both wheels will fairly quickly lock up badly with lots of nasty smoke.

My guess is one of the pips was wrongly fitted on the recent attention.
You need to check both sides as I think that the correctly piped side is the one that keeps over auto adjusting and binds up.
If it has gone on for a while one pad will be far more worn than the others and you need new pads.

John

On my Cobalt car I felt the brakes were a bit sticky and decided to check the pads. The problem was fairly obvious when I saw both the pads with pips on were fitted into the o/s caliper and the n/s had no pips.

[russ92xmsed]

Thanks John and Will. I will investigate as soon as possible. I'll let you know with photographic evidence!
All the best

Russ

[russ92xmsed]

Hi Guys, I really need your help now....

Here are some pics below to help explain what I found this afternoon. The passenger side inboard pad has uneven ware. The pads seemed to be located in the caliper like they should be....pips in the correct place.
Caliper looks like it is 20 years old...which it is, but couldn't really see if it was sticky or not. The discs seem to be in okay condition, but they do have a good ridge on them. Might be a little warped,
but the juddering under braking doesn't happen.
Yet to check the doseur valve...but would there be anything else that could be causing the trouble. Clearly something has happened as the brakes were definitely binding by the ware on that pad.
Also to note, it braked fine and without squealing when I drove it round to the garage. But they were stone cold!

To add to this, I have noticed that when the car is put in to it's highest suspension setting, the back pops up right away, but the front dips down as it is rising...and stays there unless you add some revs and then it pops up.
However in the time of getting the trolley jack out and loosening the wheel nuts, the front had sunk to a point where I couldn't get the jack under the car. That was no more than 5-10 mins at the most, even less infact.

Am I barking up the wrong tree when I am suspecting a duff accumulator here. I know the test of it clicking ect..but if there is a tail tail sign of other things misbehaving because of it, that might be a reason why the brakes are up to no good and effecting the doseur. Now I am absolutely no expert at all, so I have probably made this all up!!
Annoyingly it was done with in the last 6 months by a specialist, which kind of sheds some doubt on that idea I suppose.

The pics....Some opinions would be great!

[Dieselman]

If both pads are wearing unevenly I would suspect the caliper pins to be worn, For the weird hydraulic operation it could be the accumulator, but more likely the system pressure or FDV is not allowing full pressure.

Another thought is air being drawn in by the pump intake hose, try twisting the joints where it connects to the pump and the tank, to see if they can be turned, if so they are loose.

[russ92xmsed]

Good idea Will, Cheers.
The odd thing about the pads, is that the inboard one is only waring unevenly. The other outboard one is fine!

[xmexclusive]

Hi Russ

How deep are the wear ridges at the edges of the disks?
It looks to me as if the pads are almost new.
The friction material of new pads only needs to be a little bit wider than a deep wear channel on the disks to give problems.
Cannot see the inner edge channel but the bright line beyond the outer one on the disk suggests a possible problem to me.
I think your pads may be sitting on the inner edge of the disk channel and slightly overlapping the outer one.
This may cause the pad steel backing to bind to one side of the caliper slots which causes the caliper to bind on its slide.
When breaking the pads are trying to grind away that outer steel edge which is where the red rust on the outer half of the pad is coming from.
My next step would be to get the outer ridge ground off the disks or try a new set.
Its going to take a surprisingly long time for the existing pads and disks to bed together so not a good option.

John

[CitroJim]

Russ, I have exactly the same hydraulic problems as you have, precisely. Not been able to check the accumulator yet as it's not an easy job on a TCT but I'm much more inclined to suspect the FDV. It does do an awful lot of hissing...

[Dieselman]

I'm not convinced that hissing indicates a problem with an FDV. The only one I've had trouble with had a coil-bound relief spring.

It would bring the STOP light on flickering at idle after a few minutes and when pressing the brake the rear would dip .

[CitroJim]

Ahh, now that's interesting Will...

I really must summon up the energy to get at the accumulator... It's like an elephant in the room at the moment

[russ92xmsed]

Hi Chaps,

Thank you so much for your advice. John I think you have the answer. It makes total sense. I will check the discs again. I have a small hunch that disc might be slightly warped. So I think I'm in for changing discs and pads again.

Interesting Jim, partners in crime...suspension crime. Well I would be very interested in knowing how you solve your issue. I have noticed mine hisses quite a bit too. I'm going to check to make sure it isn't drawing in air like Will suggested.
Please excuse the ignorance...is the FDV the accumulator?