Rear break disks wearing unevenly

[VolvoRob38]

Hi all,

Here again on a new fault finding quest lol

Can anyone tell me why my rear break disks are wearing unevenly (will attach pics).

I took it for the MOT last month and the lad said I just need to tighten my handbreak and take it for a good run (because I dont use it often working from home, today is the first time in 3 weeks its moved. Had to jump start it!)

So I took it for a run 3 weeks ago and kept tweaking the hand break until the noise stopped or lessened considerably anyway. I thought nice, easy job, I'll perfect it next time I go out.

Went out today for the first time since and the metal rubbing noise was back. So went for a drive to charge up my battery and tighten the handbreak some more. The rubbing noise kept reducing, until I hit the break a few times, then it was back. I tightened it to the point I could smell the handbreak burning... Oh ****, over done it!
So slackened it off 3/4 a turn, but the noise wasnt getting any better. Tried loosening the handbreak several turns back to where it was originally and the rubbing noise got considerably less. "Did he say tighten the handbreak or loosen it" lol.

Anyway, even though it seems to be rubbing less, there is still a metal rubbing noise which sounds awful when driving next to parked cars, or anywhere the sound can bounce back at me through my open window, so need to sort it.

As its both rear disks Im wondering if I need a new hand break?

I did change the pads and disks a while ago but had no issues soon after doing that. I did cross thread one of the caliper arm/bracket things, but got my guy at the garage to re-tap it and it was OK. I did wonder if the thread may have given way or something and thats whats causing it to rub, making the caliper not sit straight. But he said that wont be it and the re-tapping would be sound, plus nothing looks like its not sitting right, and its on both sides. So was thinking handbrake.

Any ideas from you awesome lot would be much appreciated.

TIA

[SnineT]

That one is easy on a car of that era,

Your piston is dirty inside the caliper, it's a simple remedy, just push the pistons back as if you were changing the pads, the more worn they are the better for this, then pump them back up without removing the pads, "brake res cap off obviously" do this 5 times and you should be able to feel the brakes clamp on better, whoever told you the cable needed adjusting is having a laugh, the only time the cable needs tightening is if the handbrake isn't holding on a drum assembly,

Make sure you anti seize the pads where they need to slide a bit, same thing with the guide pins as one of those might be sticking, and wire brush the whole lot off where there's surfaces meeting each other not the disk or pad friction surfaces though

Looking at the pics it looks like one side hasn't worked for some time as there's no ridge.

[VolvoRob38]

Originally Posted by SnineT

That one is easy on a car of that era,

Your piston is dirty inside the caliper, it's a simple remedy, just push the pistons back as if you were changing the pads, the more worn they are the better for this, then pump them back up without removing the pads, "brake res cap off obviously" do this 5 times and you should be able to feel the brakes clamp on better, whoever told you the cable needed adjusting is having a laugh, the only time the cable needs tightening is if the handbrake isn't holding on a drum assembly,

Make sure you anti seize the pads where they need to slide a bit, same thing with the guide pins as one of those might be sticking, and wire brush the whole lot off where there's surfaces meeting each other not the disk or pad friction surfaces though

Looking at the pics it looks like one side hasn't worked for some time as there's no ridge.

Thanks Snine,

So have I got this right;
Take calipers right off the disks, push piston in all the way and then can I just sit the caliper back on the disk with pads in place and pump the break? Do this 5 times.
Should I feel the piston start to push in easier as I go so I know they are getting free of the grime and crap that Im trying to shift?

Also re anti seizing the moving parts, can I use break grease on the lot, or it that just for the caliper pins, and need something else for anti seizing i.e. copper spray or something?

Its funny yknow because every time I go to the garage there is always some little issue that Im convinced they set up to try and make more work for themselves, or they hope to at least. My mot was told I needed a new headlight because the beam was at the wrong angle. Turned out the bulb just wasn't sitting correctly lol. I told them Id replaced it like they said but I hadn't. What do you know it passed lol.

Is it normal for these pistons to get clogged up at the same time? Because its on both rear disks thats why I was thinking handbrake myself. Front disks are both fine.
I dont use the car much like I was saying, but looking at those pics, would I feel anything when Im breaking if one side rear wasnt working at all, like pulling or anything? Ive not noticed anything obvious.

Thanks

[Simmy]

those discs look bad refurb the calipers and get new discs and pads . use car parts for less for good value

[XC90Mk1]

I have changed my own discs and pads for 20 years and frequently at end of life they look like that. I attribute this to glazed and worn discs and hve never had any issue once the disc and pad axle set is replaced.

I would

1). Go for a drive, break hard and ensure it pulls up true.
2). Feel the wheel (not disc or caliper) and make sure wheel is not hot (or equal mild heat each side).
3). Replace axle set disc and pads.

After 20
Years playing with vehicles I would be suprised if it is anything other than worn end of life disc and pads.

I note the comments from others regarding the campers refreshed. Good input but may not be required - certainly if both sides look like that it’s unlikely (not impossible) that both calipers are out.

[SnineT]

Originally Posted by VolvoRob38

Thanks Snine,

So have I got this right;
Take calipers right off the disks, push piston in all the way and then can I just sit the caliper back on the disk with pads in place and pump the break? Do this 5 times.
Should I feel the piston start to push in easier as I go so I know they are getting free of the grime and crap that Im trying to shift?

Also re anti seizing the moving parts, can I use break grease on the lot, or it that just for the caliper pins, and need something else for anti seizing i.e. copper spray or something?

Its funny yknow because every time I go to the garage there is always some little issue that Im convinced they set up to try and make more work for themselves, or they hope to at least. My mot was told I needed a new headlight because the beam was at the wrong angle. Turned out the bulb just wasn't sitting correctly lol. I told them Id replaced it like they said but I hadn't. What do you know it passed lol.

Is it normal for these pistons to get clogged up at the same time? Because its on both rear disks thats why I was thinking handbrake myself. Front disks are both fine.
I dont use the car much like I was saying, but looking at those pics, would I feel anything when Im breaking if one side rear wasnt working at all, like pulling or anything? Ive not noticed anything obvious.

Thanks

Here's how 2

Check whether the rear calipers are push back or wind back, don't push winding ones in without a proper wind back tool, the rest assumes they are push back,

Put the car into 1st or Park if it's auto and leave the handbrake off,

Remove a wheel at a time after jacking up the car, use an axle stand to support the car not the jack once in the air,

Undo the brake fluid cap on the master cylinder,

Now get a strong flatblade screwdriver inbetween the pad on the outer side and the caliper, once it moves the pad switch to levering the one on the piston side and lever the pad back until the piston stops,

If the pads are thick still take the outer one out and push the piston back by using a strong lever against the outer edge of the caliper and inner part of the disc (not the surface where the pads work), then put the pads back in so the piston can't be squeezed out of the caliper,

Now pump the brake pedal until it goes solid,

Repeat this until you are happy they are going in and out ok, I suggest 3x, more if it's still very hard to push the piston back,

Once you are happy the piston is moving remove the pads and pull the slide pins out one at a time, clean the caliper bracket where the pads sit in with a wire brush and then put some copper slip in those channels, just a smear, do the same thing to each slide pin when you've got one out then replace the pins and pads and tighten everything up,

Switch sides and repeat the above,

You should now have both sides working and will see the rust clear off within a couple of test runs up the road to bed them back in,

Don't worry about new parts for now if you've not long replaced them, do not use brake grease or any other grease on the brakes, use either copper slip grease or proper brake grease that comes in sachets, i.e don't be tempted to use normal or high melt grease

Now you need to undo the handbrake bodge, simply try to slacken it back off the same amount you wound it up, you may want to do this as your doing your first caliper otherwise you'll need to jack both sides up at the same time, simply part the pads away from the disc and then adjust the handbrake until the disc just spins freely without a noticeable drag, if you adjusted them at the drum then you'll have to do each side independently anyway, you should aim for the handbrake to ratch up 3-5 clicks before the brake holds, 3 was always the norm but the Volvo might be different,

Don't forget to pump the brakes and replace the brake cylinder cap.

To answer your other questions,

Don't take the caliper off to do this, you may have to after pushing back the pads a bit remove one bolt to enable you to get the pads out,

Garage, find another if they're telling you you need a new headlight for a loose bulb,

Looking at your discs one is working the other isn't, notice one is scoring the disc more and also has a slight lip the other doesn't.

[VolvoRob38]

Originally Posted by SnineT

Here's how 2

Check whether the rear calipers are push back or wind back, don't push winding ones in without a proper wind back tool, the rest assumes they are push back,

Put the car into 1st or Park if it's auto and leave the handbrake off,

Remove a wheel at a time after jacking up the car, use an axle stand to support the car not the jack once in the air,

Undo the brake fluid cap on the master cylinder,

Now get a strong flatblade screwdriver inbetween the pad on the outer side and the caliper, once it moves the pad switch to levering the one on the piston side and lever the pad back until the piston stops,

If the pads are thick still take the outer one out and push the piston back by using a strong lever against the outer edge of the caliper and inner part of the disc (not the surface where the pads work), then put the pads back in so the piston can't be squeezed out of the caliper,

Now pump the brake pedal until it goes solid,

Repeat this until you are happy they are going in and out ok, I suggest 3x, more if it's still very hard to push the piston back,

Once you are happy the piston is moving remove the pads and pull the slide pins out one at a time, clean the caliper bracket where the pads sit in with a wire brush and then put some copper slip in those channels, just a smear, do the same thing to each slide pin when you've got one out then replace the pins and pads and tighten everything up,

Switch sides and repeat the above,

You should now have both sides working and will see the rust clear off within a couple of test runs up the road to bed them back in,

Don't worry about new parts for now if you've not long replaced them, do not use brake grease or any other grease on the brakes, use either copper slip grease or proper brake grease that comes in sachets, i.e don't be tempted to use normal or high melt grease

Now you need to undo the handbrake bodge, simply try to slacken it back off the same amount you wound it up, you may want to do this as your doing your first caliper otherwise you'll need to jack both sides up at the same time, simply part the pads away from the disc and then adjust the handbrake until the disc just spins freely without a noticeable drag, if you adjusted them at the drum then you'll have to do each side independently anyway, you should aim for the handbrake to ratch up 3-5 clicks before the brake holds, 3 was always the norm but the Volvo might be different,

Don't forget to pump the brakes and replace the brake cylinder cap.

To answer your other questions,

Don't take the caliper off to do this, you may have to after pushing back the pads a bit remove one bolt to enable you to get the pads out,

Garage, find another if they're telling you you need a new headlight for a loose bulb,

Looking at your discs one is working the other isn't, notice one is scoring the disc more and also has a slight lip the other doesn't.

Im pretty sure these are wind back pistons if I remember rightly. Ive got the tool, looks a bit like one of those wine cork screw/pull openers, and has 2 nipples that fit into holes in the pistons to turn it as you screw. So Im guessing I'll have to remove the calipers to do this because I dont think pushing the piston back with a screw driver will work. I dont think Id get the pads out without removing the caliper either.

The handbreak isnt too bad, abit high for my liking, possibly more than 5 clicks, so probably need a tweak.

The pads themselves are still pretty thick, Im sure I only changed the pads and disks last summer, if not, it was the summer before during lockdown. And as I work from home and dont use the car that much I would think behind the surface rust in the pics they should still be good. I am about 100m from the beach and the salty sea air is notorious here for attacking anything metal. And with no garage its one of the pitfalls of living by the sea lol.

I was just looking online about anti seize and there is quite a lot of opinion on not using anti seize because ot will clog up the breaks after a few thousand miles. I changed the disks and breaks for the first time on this car and wonder if I used too much grease that has got clogged with grit and dirt cause them not to work properly and seize up. I can be over generous and over tighten everything lol.

Im pretty confident I can do this. Just need some copper grease and get the wheels off and have a look. Cheers l, will report back with progress report 👍🏻

[Simmy]

the disc on pic no3 is pitted at the top thats not surface rust. dont take risks with brakes just change them your life is worth more than that.

[Volvocano]

Originally Posted by Simmy

the disc on pic no3 is pitted at the top thats not surface rust. dont take risks with brakes just change them your life is worth more than that.

What's the problem with pitting? Are drilled discs dangerous? In the old days it was common for motorcycle racers to leave a set of discs out in the garden after thoroughly degreasing them then spraying them with salty water to get the maximum amount of rusting and pitting to aid wet weather performance.

Now we have sophisticated multi-channal electronics looking after the car's dynamics, I suspect you could fit different pads, discs and tyres to each corner and nobody would notice the difference - the car would still pull up straight as a die under emergency braking conditions. I'm not suggesting anyone do this but my point is pitted discs are not an issue since the risk of pirouetting down the road from unbalanced brakes has practically disappeared. Cracked discs - fair enough. Pitting? Who cares other than misinformed MOT testers?

If an MOT station fails you for pitted discs ask them to point out under what rule they are failing you on as pitting is not necessarily "significantly or obviously worn". As long as a car passes the brake test in terms of power and balance and there's no physical cracks, breaks or leaks anywhere, there's sufficient disc and pad material - the car should pass. Obviously they can fail it on ABS warning lights, corroded brake pipes, insufficient fluid etc. Getting drivers to replace perfectly serviceable pitted discs is one of the biggest motoring scams out there.

Incidentally, if you find yourself in a deserted car park, reversing hard then applying the brakes hard is a good way of cleaning up the rear discs - the weight transfer to the rear will put some brake load on the rear - particularly where load sensing valves are fitted. Obviously only contemplate this where you are 100% absolutely alone and there's nothing/no-one to hit!

[IainG]

Hi
Be careful adjusting the handbrake cable. If the callipers are the same as mine with the wind back pistons and self adjuster on the calliper for the handbrake.
If you try to tighten the handbrake cable too much, the levers on the callipers come off the "stops" this then stops the self adjusters working. You then tighten the cable a bit more and it all gets worse.
The 2 levers, one on each calliper, that the hand brake cable operates need to sit on the stops when the handbrake is off, otherwise the adjusters stop working. My handbrake lever is higher than I would like but the self adjusters do work, has just passed the MOT like that.
Be careful with the wind back tool and ensure you rotate the correct way. Some callipers are clockwise and some are anti-clockwise,