I posted a thread some months ago regarding brakes, this is a related but not identical question.
I have just changed the wheels from summer to winter on my Aero auto estate. I noticed while I was doing it that the rear brake pads on the drivers side have worn down to their limit only a year since I replaced the discs and pads. Normally I would expect around 3 years/50k miles from a set. Both the inner and outer pads have worn evenly. I'm thinking therefore that the problem is a sticking piston.
Before I spend good time and money on the job, does this sound a reasonable diagnosis? In normal circumstances I'd say so, but I noticed the wheel was spinning freely before I touched anything (I was checking for free rotation in order to assess handbrake adjustment), so it just planted a seed of doubt in my mind.
The same problem exists to a lesser extent on the passenger side. The car has covered 217,000 miles with no attention to the brakes other than pad/disc replacement and appropriate copaslip attention to the bearing surfaces on the caliper holder and the guide pins.
Just as an aside, the rear suspension and wheels seem to attract significant road dust/mud etc, and the driver's side is the nearside (remembering I have lived in Austria for 5 years and drive a RHD car). I wondered if this is why the problem was greater on the one side?
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No chance the handbrake was left on? (if you can do that in a Saab).
Or perhaps he handbrake was adjusted too tight and the wheels started spinning freely after it had worn half the pads away?
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>> No chance the handbrake was left on? (if you can do that in a Saab).
>>
>> Or perhaps he handbrake was adjusted too tight and the wheels started spinning freely after
>> it had worn half the pads away?
>>
Doesn't work like that Mark, the handbrake works via independent shoes inside a drum integral to the disc, so there's no relationship between the foot and handbrakes (there used to be on the Saab 9000). Thanks for the thought!
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Worn pads on one side is indeed sticking pads - as you say caused by one side being muckier than the other.
Was surprised when I got an advisory on the lancer for worn rear pads on one side. One side worn to a near frazzle the other pretty meaty.
I have them out and cleaned up once a year.
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>> Worn pads on one side is indeed sticking pads - as you say caused by
>> one side being muckier than the other.
>>
>> Was surprised when I got an advisory on the lancer for worn rear pads on
>> one side. One side worn to a near frazzle the other pretty meaty.
>>
>> I have them out and cleaned up once a year.
>>
So what do you actually do in the way of cleaning them up? I don't want to strip the hydraulics out, and I'm reluctant to buy reconditioned calipers if I can restore normality without doing so, although that's the backup option. The reluctance to strip the hydraulic bits is nothing to do with mechanical competence, simply that only having the one car, and living in the sticks in Austria, means that we can't afford to be without the car when something goes wrong as it invariably will!
Last edited by: Mike H on Thu 30 Oct 14 at 13:36
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Possibly a sticking caliper or a partially collapsed brake flexi hose.I would think that the parts are similar to a vauxhall vectra,so recon caliper easily available if this is the problem.
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Thanks carmalade, I am 99% sure it's a sticking caliper. Not so sure the actual caliper is interchangeable with a Vectra, although I occasionally buy suspension parts from the local GM dealer.
Having spoken to the garage this afternoon, they are going to take a look next week. The receptionist told me that this type of thing was common in country parts round here and they see a lot of this type of problem, probably due to the salt in the winter and large quantities of dirty slush not to mention simply dirty water from the sometimes large quantities of rain. Seems it's not so common in the cities.
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>> So what do you actually do in the way of cleaning them up? I don't
>> want to strip the hydraulics out, and I'm reluctant to buy reconditioned calipers if I
>> can restore normality without doing so, although that's the backup option. The reluctance to strip
>> the hydraulic bits is nothing to do with mechanical competence, simply that only having the
>> one car, and living in the sticks in Austria, means that we can't afford to
>> be without the car when something goes wrong as it invariably will!
Its not the hydraulics sticking, so I leave the piston alone. I take out the pads, and any guides/carriers. Clean up the surfaces of the calliper where the pads slide with a wire brush, clean up any carriers, guides and pins, get a gentle file and dress the sliding metal parts of the pad and then lubricate all the sliding surfaces with copaslip.
Last edited by: Zero on Fri 31 Oct 14 at 18:32
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Edit
If I don't do the above once a year, the pads stick and I end up with corrosion strips on the disk and juddering brakes. Its caused because the car is massively over endowed with disk surface and I am light and early with braking.
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>> Its not the hydraulics sticking, so I leave the piston alone. I take out the
>> pads, and any guides/carriers. Clean up the surfaces of the calliper where the pads slide
>> with a wire brush, clean up any carriers, guides and pins, get a gentle file
>> and dress the sliding metal parts of the pad and then lubricate all the sliding
>> surfaces with copaslip.
>>
Thanks for the update Zero, that's exactly what I do when I replace the pads. As I replaced them only a year ago and diligently carried out all that work, and they have worn to their limit, it's a good indication that the hydraulics are perhaps due for attention at 10 years/217,000 miles. As I mentioned, the garage are used to dealing with this type of problem so I'll let them take a peek. They're well aware that I don't want to spend an arm and a leg on any repairs except as a last resort!
Exchange calipers would cost €105 here (c. £80), which I didn't think was too bad. There is an intermediate option of new guide pins, and the associated rubber seals, but I'm not convinced there would be much gain from that.
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I don't know why you wouldn't push the piston back when you're doing all the other work.
I keep an old pair of worn pads that I fit temporarily, pump the piston out and push them back several times. They usually slide much easier after. I bought a wind-back tool for the rears quite cheaply. I've heard an argument that doing this can tear the seals if there's any corrosion on the cylinders. I personally feel that if there is, then the seals would tear sooner or later and doing what I do would show this up while I've got them dismantled.
I also use the opportunity to pump a bit of new fluid through at each wheel.
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I'm in the Z school of brake servicing.
As regards new cars, my experience is that the wheels don't come off for 3 years. I recently disposed of 2 vehicles that reached that milestone with lower than average mileage. Although a bit anal about such things both had a full set of discs and pads, front and back. The backs could have survived a while longer with a bit of dressing. The fronts were not good.
Why? Everything was gummed up. Certainly the improvement in baking performance on the Ceed was immense.
So an annual caliper cleanup can pay dividends despite what the manufacturers recommend.
Last edited by: Fullchat on Sat 1 Nov 14 at 17:22
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Never have had that problem.
Lots of steep hills here and some dual carriageways unlimited with steepish slopes and roundabouts at end..
So hard braking is the norm - I (in the dry) brake late and hard to avoid the problems others describe. In the rain and snow I am much more circumspect.
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>> I don't know why you wouldn't push the piston back when you're doing all the
>> other work.
because behind the piston the bores are bathed in nice lubricating fluid. I'd far sooner keep it that way as long as possible.
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Things to ponder?
Being an estate does it have an load/pressure limiting valve on the rear suspension?
Are the rear brakes on the same hydraulic circuit?
A partialy collapsed flexible hose can have a one way valve effect, but may release the pressure in a relatively short period so the wheels are apparently free to turn although the period the pads are in contact is much increased.
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Just to finish this off, the garage have simply "cleaned and freed up" the calipers, so probably not done much more than I would have done but there you go. Remains to be seen how long the new pads last to find out how effective their work was.
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Did you find out if it is fitted with a valve to control pressure vs load? (on rear brakes).
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>> Did you find out if it is fitted with a valve to control pressure vs
>> load? (on rear brakes).
>>
No I didn't, I clean forgot. I know it has EBD but whether it needs the valve that you mention I'm not sure. But I would have expected that to affect both sides equally.
The garage have certainly done a better job of cleaning than I usually do, there's bright metal on the caliper bracket now. Will see how it goes. The brakes overall seem improved with a firmer pedal, probably due in large part to the complete fluid change that I requested.
Last edited by: Mike H on Sun 9 Nov 14 at 09:24
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Don't these cars share the same platform as the Vectra.
The caliper sticks on it's sliders due to the aluminium corrodes internally nipping the rubber sleeve around the sliding bolt.
As with the Vectra and many other cars the remedy is to remove prise out the rubber sleeve file down the corrosion, a smear of seal grease and refit, Usually lasts about 3 years and the process starts again.
However at your (The car has covered 217,000 miles) Treat it to some shinny new ones. :-)
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SAAB 9-5 - 04 2.3 Excessive wear of rear brake pads - No FM2R
