HowTo: Replace rear flexible brake hoses

[dooby]

Hi,

today I finally got around to replacing the rear flexible brake hoses on my 850. As I'd imagined, this wasn't as easy as the fronts :-)

I chocked the front wheels, put it in park (optional for those with manual boxes!), loosened the wheel bolts and jacked up the car, placing an axle stand under the rear arm on each side.

I undid the brake reservoir top and put some clean plastic sheet over the hole, trying to make an air-tight seal with a rubber band. This should minimise the amount of brake fluid dripping under the car as you remove hoses.

Starting on the nearside, I found the first hose quite easily visible through the wheel arch. I used a wire brush and penetrating fluid everywhere I thought I'd need to work, then went back to the nearside hose.

I used a 14mm crow's foot on a wrench with an extension bar, and an 11mm brake pipe spanner to loosen off the union nearest the front of the car. As the flexible hose can't rotate, once the union was freed, it was the 11mm hard pipe end which was undone from the non-moving flexible hose if that makes sense.

Beware some of the C shaped spring clips were past their best, and one disintegrated as I undid a union so you may want a few of these handy. I imagine Rufe on here could get you a price on genuine Volvo replacements if you wanted.

Once the front end was free, I had to undo the 2 hard pipes coming into the Y splitter. Then I could undo the 10mm splitter mounting nut (careful, don't drop it into the rear support arm innards) and remove the old hose and splitter.





After a bit more brushing and penetrating spray I was able to hold the splitter with mole grips and use the 14mm crow's foot socket on the hose to separate the two.



I cleaned up the thread with a wire brush, and attached the replacement hose. I attached it back to the union at the front of the car first, then adjusted the tightness of the two ends of the flexible hose to get the splitter to sit right back where it mounts. I loosely attached it, and reattached the hard pipes with a combination of 11mm crow's foot and brake spanner.



Sadly the other hose is harder to get to. From underneath the car, I separated the hose at the offside end where it's a spring clip union with a hard pipe. With this free, I tried to undo the hard pipe nut as it attaches to the nearside end of that hose but it wouldn't budge. I realised the plastic mount the hose was sat in was mounted to the rear support arm with a Torx head bolt, so cleaned it with a wire brush and undid it. A mirror was handy for this step so you can see the top of the support arm. Once this was done I was able to undo (again) the hard pipe at the Y splitter on the nearside, and remove the whole lot to have a go at it with better access.



As you can see, I managed to undo the hard pipe from the flexible pipe (I used mole grips carefully on the plastic 'nut' housing, and an 11mm brake spanner.



Getting the old hose out of the plastic housing was harder - off to the shed to remove as much corrosion as possible. Eventually I slid the free end through a 15mm ring spanner, G clamped that to the bench and gently hammered the exposed flexible pipe end until it fell through. With the plastic cleaned up I could fit the new flexible hose.



When putting it back on the car I replaced the plastic mount and flexible hose first with the Torx bolt, then fed the hard pipe in from the nearside wheelarch again. Keeping a check it was oriented correctly I attached the hard pipe to the plastic mount end of the flexible hose by tightening the 11mm nut.

Then I was able to reattach the nearside end of the hard pipe at the splitter, as before. Finally, I reattached the flexible hose to hard pipe union with its spring clip at the furthest offside of the vehicle.

Last but not least, bleed the brakes to push through any air or dirt that may have been introduced. You may want to gently tap the disturbed items (and the caliper) with a rubber mallet to help dislodge air bubbles.

I recommend carefully checking that the brake pedal doesn't sink to the floor with the engine running and a foot pressed hard on it, and take it easy for the first few miles if any doubts. Obviously check for visible leaks and resolve where they're coming from before heading off.

HTH, Pete