Brake woes, front disc failure at low miles and other problems

I fitted this set to both our a2s 2 and 3 years ago respectively no signs of wear on either set super braking power little dust ..infact so pleased bought a spare set ..
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Howey said:
Quite a extensive and expensive kit
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I disagree with the expensive ..front and rear complete rebuild .£300 .?...with this you certainly get quality I even painted 2k the outside of rear drums apart for where wheels sit ..price up a pair of Brembo .imho and I’ve used lots of top makes on my toys over the the years really impressed with these ..it’s all relative yes of course you can buy cheaper ..you can also spend A Shed load more I paid £1500 for a pair of Front floating performance friction discs and pads on the 911 turbo s and that was nigh on 7 years ago compare that to ceramic and your closer to £5k pair ..
 
whatevershebringswesing said:
My hands-on experience is small by comparison with many talented folk who make generous contributions on here. However, I have recently fully rebuilt ATE calipers and fitted new Pagid pads (replacing Pagid) on my year 2000 Saab 9-5 Aero Estate. The issue started with a front brake fully locking on after an emergency stop. The calipers needed a rebuild anyway but the fault recurred after the work (inspected and approved by a master technician for Saabs). Despite passing MOT last week (the MOT system does not fully test the ABS/TCS hydraulics and control module ECU) the issue remains as a dragging and heat and I dare not try a test of ABS for fear of a third event of a fully locked brake (even though the smoke/steam is exciting!). While the main culprit is predicted to be corrosion and deposition of metals in the hydraulic block of the ABS unit there is another theory which may have relevance to this thread and has not yet been mentioned. Very high pressure is applied through to the piston under braking. Very little force exists for retraction. The flexible brake hoses can be outwardly perfect but act as one-way valves restricting the return flow of fluid. Two syndromes can cause this. One is deterioration of rubber inside the bore. The second is the rusting of connection components on the outside of the hose the build-up of which reduces the bore. Brakes work perfectly when applied but the pads remain in contact with the disc. This may be undetectable in a static test when the parts are cold. The other thing I have leant over the recent days is that there is a huge difference in quality in the metallurgy of discs from different sources with many on the market having inferior performance. I don't know if the suggestion of faulty hoses applies to our A2s but this thread seemed painfully familiar to me and I thought I should 'share'!! atb all
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I've been away on the boat the last couple of days, and whilst I hadn't heard of corrosion within ABS units, the thought did occur whilst bobbing about the flexible brake pipes (which I'd forgotten all about tbh). I've cut some old ones that were causing draggy brakes, and sure enough the internal bore was almost non-existent! As you say, they could expand just enough to let fluid flow one way, but not stay expanded long enough to allow it back the other. In my experience not too common, certainly compared to caliper area corrosion, but cheap and easy to deal with.

As a completely unrelated aside, one pair of hoses I cut were from my Forester: that had a series of binding brake issues which were ultimately all down to the usual piston / slider / pad edge corrosion and so on. The hoses were fine. Nevertheless, even with the brakes passing my engine-running test (above) at traffic lights etc, there was a noticeable jolt when coming to a halt. Took me a very long time (as in years!) to realise the centre diff had started to fail and was just binding the AWD system. A 'new' centre diff from a blown WRX gearbox (£20 off eBay) and 1/2 day's work, and finally all friction-like symptoms had gone. Didn't hurt the economy either which leapt from appalling to poor.

Unless Phil has sneaked a Subaru All Wheel Drive drive-train into the A2 though, I'd wager this was unlikely to be the problem ?
 
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Good to hear (from Rusty911) this endorsement of the theory that hoses could be a factor in the OP's predicament (and mine!). Partly because I ordered a pair yesterday! Given that the potential flaws are undetectable from the outside and don't affect braking performance (or the MOT), I suspect the syndrome might be quite common on vehicles - say - over fifteen years on the road. Dragging brakes can be imperceptible when using the vehicle but I expect there is premature wear and an increased quantity of air-borne particulates. Given that the hoses are cheap and relatively easy to swap I think that replacement of the flexi hoses should be considered routine when anyone is going to the bother and cost of changing or rebuilding calipers. For those that think that a car should be 'a keeper' (sensibly minimising energy and material consumption in the production process), hoses are available with stainless fittings so as to avoid the syndrome of constriction by external rust. atb to all
 
Would I be the OP referred to by @whatevershebringswesing ? No the problem could not be flexible hoses. I replace them to frequently. Just replaced them at around 5 years old
valid point though as I have seen this hose constriction problem in a classic mini that stood for a few years.
Edit, if I released the hose clamps fluid flowed out strongly. Both steel and flexible pipes were clear and allowing fluid to flow due to gravity. I had to place plastic under the Master cylinder cap and disconnect and plug steel pipes at the ABS unit so that I could work without brake fluid contamination under the car.
 
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Local ATS doing MOT £20 or £18.50 on Groupon voucher. So I booked one. The MOT tester was very complimentary about the condition of the car but said he had had to test the rear brakes several times to get the rear brakes sufficiently close I saw the figures and to be honest I wouldn’t have passed it. He suggested I bleed my brakes as he could see it was all new at the rear
I‘ve not got under the car yet, but any suggestions? Bleeding I thought an unlikely cause but will do it. Linkages wrong (I’m good at that)? Cylinder wrong bore?
 
philward said:
Local ATS doing MOT £20 or £18.50 on Groupon voucher. So I booked one. The MOT tester was very complimentary about the condition of the car but said he had had to test the rear brakes several times to get the rear brakes sufficiently close I saw the figures and to be honest I wouldn’t have passed it. He suggested I bleed my brakes as he could see it was all new at the rear
I‘ve not got under the car yet, but any suggestions? Bleeding I thought an unlikely cause but will do it. Linkages wrong (I’m good at that)? Cylinder wrong bore?
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Are they shoes adjusted close to the drums ?
If they are not then a lot of movement is need get the shoe into contact with the drum
This is normally associated with a very poor handbrake. Sometime people take the handbrake up on the cables but this is not the correct way to do it and always results in a poor foot break performance

Paul


Sent from my iPhone using Tapatalk
 
In the past I've found the 'self adjust' spring loaded wedges don't always do their job and need a bit of help.
If I remember, with the drum off I'll push the wedge back up then carefully press the brake pedal and check if it moves ok

Cheers Spike
 
depronman said:
Are they shoes adjusted close to the drums ?
If they are not then a lot of movement is need get the shoe into contact with the drum
This is normally associated with a very poor handbrake. Sometime people take the handbrake up on the cables but this is not the correct way to do it and always results in a poor foot break performance

Paul


Sent from my iPhone using Tapatalk
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Finally got a chance yesterday to look at this problem. The handbrake was correctly adjusted but for good measure I tightened it up a little.
 
spike said:
In the past I've found the 'self adjust' spring loaded wedges don't always do their job and need a bit of help.
If I remember, with the drum off I'll push the wedge back up then carefully press the brake pedal and check if it moves ok

Cheers Spike
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Finally got a chance to look at this yesterday. I backed the adjusters right off, refit the drums, applied the brakes, adjusters pulled down nicely.
 
Finally got a chance to look at my rear brakes Also found this clipped on the back of my MOT certificate:

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Foot brake down 19% across the rear axle, parking brake down 19% across the rear axle. That MOT tester is not a need to bleed the brakes problem but I did it anyway. It is more likely to be contamination of the shoe linings. So I opened the brakes, checked the adjusters as suggested, checked the hand brake as suggested and expected to find a new cylinder weeping fluid. No both cylinders are fine. Mechanisms assemble correctly both sides too.

The only thing I could find was the remnants of a dribble of paint down the inside of the drum. It appears to have been spread around rather than worn off and appears to have contaminated the lining. Cleaned both emery cloth and brake cleaner respectively and reassembled it. I have no way of checking all is well but if the problem is still there next year it needs new shoes.

Clean up any paint dribbles on your brakes fully before use.
 
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RAB said:
Sounds painful!

RAB
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Certainly is, been for a longer test drive and one side of my rear is on fire. The other side is just warm to the touch. Didn't drive hard so warm is what I would have expected.

It is the same sides as reported at the MOT test, see a few posts back. I'm beginning to think that one side is over effective rather than one side being poor. Is that possible? I've not see any reducing valves or anything.
 
Surely more likely that the disc is rubbing. That would lead to that disc being less effective but only when it's hot. Rear caliper overhaul now?

RAB
 
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