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Full Version Rear Brake Pipe Replacement Problems - 2.5 Estate

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rg
Hello Folks,

I've just started this job, and would appreciate some pointers on mounting points, please.

This is the curly pipe which appears to feed the rear caliper. It attaches to a steel bracket on the subframe, close to, but outside the subframe, just upstream of the curly bit. There then appears to be another bracket downstream of the curly bit, but on the swinging arm, inside the "cage" of the sub-frame. This was described to me by Noz. in an earlier topic posting.

Does the anti-rollbar need to come off to access the bolt that holds this plate on? This area is thoroughly corroded, and I'm not convinced that this will come off at all, as access to a bolt head is restricted by the anti-roll bar. There's no access for a decent hex. socket otherwise.

Is this whole job easier if the sub-frame is dropped? I can't quite see where the other (non-caliper) end is joined at the moment.

I'm about as depressed and frustrated as I've been in recent times in working on old vehicles, not helped by having to work outside in the wind and rain, with the clock ticking for the MOT re-test next week, and thoughts of whether it's worth persevering with this car.

Thanks in anticipation.

Rob
xmexclusive
Hi Rob

I have a removed rear subframe that I was pulling bits off.
Then I piled a load off bits on it.
I will try to get over and uncover it this evening.
See if the pipework is still intact to answer your questions.

John
rg
John,

Most kind of you to offer. However, don't worry too much, as I think I'll drop it anyway to check/treat any of the other remaining non-copper pipes. It will make measuring easier, too.

Meanwhile....

Amazingly, all four of the 10mm-headed bolts retaining the "pipe clamps" came off - hallelujah! This was a lovely surprise, as the heads were quite corroded, and I was aware that the ones into the swinging arm (the hardest to access), were into alloy.

I wire brushed, treated with Plus Gas, and used a 18" long drift with a 1/2" blade to start them off gently. One got treatment from a small blow lamp. The threads were very clean, to the point that I could wind the bolts out by hand. Not all my encounters with corroded fasteners have ended like this...

It has been yet another of those "oh my goodness" moments with the XM, not helped by the loss of both of my elderly parents earlier in the year, within three weeks of each other. Grief is a strange thing, making the challenging seem overwhelming, as was the case here. And the weather didn't help.

noz
Hi Rob,

I think you have correctly identified the two quadrant plates. One is used to fix the coil to the crossmember and the other to the swinging arm. By fixing the coil at both ends like this, all of the movement caused by the swinging arm moving up and down is taken by the coil and only the coil. The remainder of the pipe sees none of the swinging arm movement. From memory, the anti-roll bar does get in the way of the fixing bolt. It's easy enough to chop the head off th bolt with a cold chisel but you'll need to work uot how you can remove the captive nut and then make good with a new nut and bolt. I don't have one to hand but I'm sure John will be able to help when he finds his spares.

You have my sympathies in this weather. although I have a double garage it's the usual story. One half occupied by an Xm and the other with junk. I end up workin goutside too.

Cheers

noz cool.gif
rg
Noz.,

Many thanks.

Just to clarify, I used the long drift to "start" the bolt, taking care not to snap it off or distort the faces too much. I was amazed that this worked quite to easily. If I'd wanged the head off, it would have been a long job to get the headless shaft out of the blind hole. Patience paid off in this case. I thought it would be much worse.

Tomorrow I'll drop the subframe at one side and trace the other end of the pipes. From memory, they go into a three-way union on the upper face of the large tube cross member.

The weather is forecast to be the same tomorrow. I came in at 2-45 when the water had got through waterproof heavy-duty Network Rail jacket, overalls, and T-shirt...

r
noz
Hi Rob,

That is good news. You've passed what is probably the worst part of the job. You are right about the non-caliper end of the pipe. It does indeed go into a 3-way union which is in a little plastic cradle fixed to the crossmember. The next bit of luck you need is to be able to get the tubing nut loose on the 3-way union. Rather than waste any time I usually just take a hacksaw and cut the pipe off just above the tubing nut. That allows you to get a good 6-point (not 12 point) socket hammered on so that you get a good grip. If it doesn't move with moderate force (which is not a lot, bearing in mind the size here) I usually resort to a bit of OxyAcetylene heating and accept that I will need to replace the rubber seals. This is done in a way so as to protect the plastic cradle from the heat.

At least, under the car, you are offered some protection from the rain. Can you throw a tarpaulin over the car to form a tent?

Please come back periodically for some moral support. It helps, I should know.

cheers
noz cool.gif
rg
Noz.,

Thanks, once again.

I've repiped here before, having done the major front-back ones plus others, so usually do just as you say with the nuts. The brass 3-way clips out of the cradle, so heat should be no problem to the plastic.

Yes, indeed - it was actually good to get right under the car! However, the clamp nuts on the swinging arm have better access from the outside, so that's what took up the time and got me soaked.

I've backed the car up to the garage door, and opened the hatch, so this gives me some shelter. I have a cheap gazebo, but the wind is too high for it. Likewise a tarpaulin. We've had up to 40mph off the sea today.

Thanks for the moral support, advice, and understanding!

r
rg
Phew! All done!

The car passed yesterday afternoon. Here are some points on the repiping of the rear brake pipes.

- This job can probably be done without dropping the subframe totally, and leaving one side attached but loosened,but I did just for ease of access.

- The quadrant plates are your major challenge. As per above, these clamp either end of the curly pipe. Try and get a head-start with some penetrating fluid on the bolts, having thoroughly wire-brushed.

- Access to the bolts to the swinging arm is very tight, and it's easy, in haste, to round the bolts off. I didn't, thankfully, but managed to "start off" both of them gently with a long, thin drift on a corner of a face. You can clean up the faces when they're off. Amazingly, once I got them moving, they came out by using my fingers. A "stubby" 10mm spanner may help. A full ring spanner won't go round the bolt head due to the pressing of the steel plate. The bolt is a very tight fit against the roll bar, but will come out. They will go back in with your fingers if cleaned and greased,, and can be tightened with a drift, with care. If you really get into trouble here (stubborn/snapped bolt, rounded head), it might be wise to try and take the roll bar off. I'm not sure how easy this might be, as the fasteners sit out in the muck, and mine were quite wasted...

- Observe and copy the direction of "winding" of the curly bit. It should point down from the swinging arm end into the coil, and then leave pointing upwards to the tubular cross-member. I messed up one, and had to do some creative bending of pipe. For your information, the length of pipe coiled up alone is a remarkable 1300mm.

- The sub-frame-mounted pipe clamp bolts are secured by a captive nut, which may not end up being that captive... The fact that the bolt will turn does not mean that it will come out, as the far end of the thread may be rusted. Actually, it does not have to come out - the clamp can be loosened and the pipe slipped under. I ended up in the horrifying state of having the bolt seized in the nut, and the inaccessible nut spinning - one of those "can't go forward - can't go backwards" situations. I ended up jamming the nut with a screwdriver (just about possible behind the bracket) at which point the bolt calmly came out. So, how to reattach, with no hope of using a captive nut? As soon as I saw the hole in the tube, I thought "stud wall cavity mounting". You may have seen those "butterfly"-type spring fasteners used to attach things to stud walls (plasterboard and timber frame). They use an M8 bolt. If the hole is widened a little, one will fit in, the spring bits will open and secure the bracket. Perfect!

- The pipe does an S-bend in the arm-based bracket. Good and flexible as the pipe is, don't try and form it in that area - cut the old pipe above the caliper union and just short of the curly bit, and copy that. One side took me a desperate hour (it was "almost there" for most of that time, but needs to fit perfectly for the bracket to close up), the other side, off the car, formed using the original as a copy, it took less than ten minutes.

- Pipe routing. I tend to leave the old pipes in situ, and cut off lengths as I go along, feeding in the new pipe. Large side-cutters snip it well without creating swarf. Tape the end of the pipe well to stop muck getting in as you thread it through. There's enough space above the tubular cross-member to "lose" any excess length in case you've mis-measured.

- The best bit about this job is that you only have to do it once.... Try and "potter" with it, rather than doing it in a monsoon, outside, not feeling emotionally good, with the MOT retest and family commitments looming. (Ask me how I know!)

That's all, folks!

With kind thanks to Norrie and John.




-
xmexclusive
Hi Rob

Thanks for the write up.
I aim to start refurbishing a spare rear subframe this winter.
Then gradually swap them through the cars.
Picked up quite a few pointers from your comments.
Am amazed at the length of pipe needed for the full job.
Had previously grossly underestimated this.

Glad you got all done for the MOT.

John
noz
Well done Rob,

That's another year of life gained for the old girl. As you say, the time to do this is not when its actually required but in the middle of summer when its quiet and the car is not needed and the pressure is off. However, it never seems to work out that way for some reason rolleyes.gif

You're more than welcome.

cheers
noz cool.gif
rg
Thanks, chaps!

Your support is always appreciated.

I'm just back from a weekend break with my wife, and it was gratifying to drive the old girl, knowing that only a few days before, the rear end was dismantled, and reassembled by my own (oily) hands!

r
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