peteS40

Latest news on this brake problem - see what you experts out there think because I think it is a friction problem of some description?

Over the weekend I took apart the right rear caliper and replaced the seals. Very light marks on the piston, rubbed it down with very fine abrasive paper, cleaned it all up and put back together. The right hand side was the one getting hottest.

Didn't get chance to do the left caliper because it has being raining most of the weekend and didn't fancy working in the cold & wet!

But on both sides I cleaned up the pads carriers and the pads, coated with copper slip and put it all back.

Now there were a couple of things of interest:
1) The discs need replacing. They are worn below the limit. I scraped off the rust lip round the top while I was there.
2) The outer pad on the left hand side (not the side which I removed the caliper) had more of a glazed appearance than the other three and a fine coating of what looked like rust. It was also not exactly the same thickness as the inner pad on that side.
3) The handbrake was clearly not binding, at least not when everything was cold.
4) The caliper guide pins were free to slide although since new rubber boots came with the repair kit then I overhauled the ones on the right rear while I was there.

One thing to note: the pads are new, they were changed just before I got the car < 2000 miles ago.

I put the fuse back in the ABS, cleared the fault code, adjusted the handbrake, put all the trim back and took it out for a drive.

It was certainly improved, the pedal was not hard and seemed as normal. After a while of gentle braking to make the rear pads bed back in following removal I tried some heavier braking. At first everything seemed ok but then it did the ABS problem again, but only a few times.

But then I worked it out - it seemed to be when everything was hot. As it had been raining and was cold the brakes seemed to cool down quickly. If I did a bit of heavy braking then I could get the ABS to come on but the pedal - and the ABS - behaved as you would expect (pulses through the pedal as ABS activates). But then short time later the pedal would feel hard again and then the pedal would 'give' with the ABS activating.

Diagnosis & Conclusions

To me the nature of the problem suggests a friction problem at one or both rear brakes. I no longer think it could be related to e.g the pressure regulating valve or maybe the master cylinder unless there was some strange fault that was intermittent but only occurred if the fluid got hotter and never affected the front. That would seem to odd to be possible. I think the ABS can be ruled out because it is just something that responds to the rear brake problem signified by a hard pedal.

I think that changing the rear discs is the logical next step because these are worn out. I think that the rear pads are likely not making proper contact with the disc for some reason not sitting were previous ones did and maybe contacting the disc rust instead, at least maybe this could explain the left rear outer pad appearance?

But also I am thinking at least one of the caliper pistons is sticking maybe so it is not retracting properly when hot causing the brake to bind and then under next braking that brake proceeds to start to lock? One thing I did was to rewind both calipers, obviously the one I had off but the other one as well so both have kind of been 'adjusted'. Also bled through the rear brakes fluid clean and no air (fluid was all changed recently).

Your opinions would be very much appreciated in this on-going saga. I don't really want to throw more money at the brake problem unless it is going to resolve it, I don't just want to change anything "just in case". There are also plenty of other things that need doing to this car.

The other thing is that I am, quite frankly, getting a bit fed up because this problem seems to be an "unknown" thing: if I know what is needed I can plan and budget for it. It is getting to the point where I am thinking of possibly getting rid of the car, if I cannot resolve this problem soon. I will not do that if I can spend just a little more to fix this issue because then I am back in "ok, that is a known problem just got to fix it then the problem goes away" territory and at least feel improvements are being made. Of course any other car - volvo or otherwise - would likely have other faults and I'd make a loss selling the car esp. so soon after purchase, plus if this car was fixed then I'd enjoy it a lot I am sure! But I am getting fed up and it might be better to "quit while I'm behind" as it were.

Pete