Rear Brake Line Replacement

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Dytie
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Rear Brake Line Replacement

Post by Dytie »

I recently acquired a mk1 16v project from a well known forum member who’s username rhymes with Hitch that I’m planning to restore. It needs recommissioning, some welding and a paint job but I don’t think it’s too bad considering it’s been off the road for over a decade.

I’ve haven’t an opportunity to go over the car with a fine tooth comb yet to establish exactly what needs doing and to formulate a plan of action, but the first thing I’d like to address is the leaking O/S rear brake pipe as it’s making a right mess on my garage floor.

Yesterday I jacked the car up to take a closer look and found LHM dripping from the metal brake line about 2 inches before it goes into the calliper.

It appears I can get a replacement easily enough but I have a few questions:
  • Is it possible to replace the rear brake lines without having to drop the subframe slightly so the pipes can be carefully threaded where they need to go.
  • When I disconnect the brake line from the splitter valve, am I going to get drowned in LHM? I assume the system is constantly under pressure judging by the pool of fluid on my garage floor. Perhaps it’s just because I had the suspension on high the last time I fired it up?
  • Where should I buy the LHM brake line seals from - I think I need 3.5mm
  • Obviously I’ll also need new calliper bleed nipples. Any idea what size I need to look for and where to source these from? I found this info on another post but not sure it applies to the 16v (fronts: m7 x 1) (rears m8 x 1.25)
Thanks for any replies in advance. I’m sure this will be the first of many questions while I get to grips with everything.

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Re: Rear Brake Line Replacement

Post by rutter123 »

You won't need to drop the subframe to replace the hard brake lines (the ones with the coils in?) these are just held in place on plastic clips and 2 metal quadrant shape clamps which attach to the rear beam and the anti roll bar brackets, tho I think they pass through part of the the subframe. If you mean the hard strut supply lines then they can be a different story if you can't get the fittings out of the strut which is tricky to get to anyway and can request the removal of the strut itself Personally I would fit new ones on both brakes and struts as otherwise you may spend many more weekends replacing them one by one, not too bad a job if the fittings come out easy.
If you relieve the pressure in the system by putting it in low and let it sit for a bit without the engine running, this should be enough so you can change the pipes, you will get some drips but not sprayed on. Never do any work with the system pressurised.
Reverse up onto to ramps for better access then depressurise.
Pleaides in Sawtry can help with most Citroen hydraulic systems, they make pipes to order etc
Bleed valves are available from Pleaides on ebay, motor factors, they not specific to the bx just be careful they're not too long, I'm not sure if the 16v ones are different I wouldn't have thought so.
The pool of fluid on your floor will slowly be emptying your LHM tank so check level. You can just clamp the pipe with some mole grips to stop the leak if your replacing the pipe anyway or catch the spill in a clean container
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Dytie
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Re: Rear Brake Line Replacement

Post by Dytie »

Thanks for the info. Yes, I'm talking about the brake lines with the coils in. I'll give Pleaides a call.

I ended up crushing the pipe as suggested to stem the flow which has certainly helped and will be fine as an interim measure.

Cheers!

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Re: Rear Brake Line Replacement

Post by DLM »

rutter123 has covered most bases - I'd also be sure set to low position jacked safely with the hydraulic system fully depressurised before any work.

I'd also get to know how to release pressure at the pressure regulator before starting hydraulics work - if you don't know it already. The "pressure regulator release screw" as Haynes describes it, is a bolt on the pressure regulator - which should only ever be unscrewed one and a half turns.

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Re: Rear Brake Line Replacement

Post by rutter123 »

To relieve any probs removing the original 8mm pipe fittings, cut the old pipe about 1/2 inch above the fitting and then get a decent 8mm long reach socket on it, don't try to get any out with an open ended or cheap nasty ringspanner or they will round off and then it's headache. Some (especially the rear strut ends can be particularly stubborn) Soak them overnight with plus gas take your time and they should come out ok, make sure you get ALL of the old rubber seal out. I found a crochet needle ideal for hooking them out.
New pipes from Pleaides will come with 10mm fittings which makes refitting easier.
As /\ says the pressure relief valve is a 12mm bolt head on the front of the regulator and you unwind it too far a spring and ball bearing will be lost forever.
If you have a bad leak chances are you will have no pressure in that line anyway.
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Re: Rear Brake Line Replacement

Post by mat_fenwick »

As stated, bleed screws are nothing special, and 16v no different (the hydraulic part is the same on the calipers). I'd check what size you actually have before purchasing, as it may have been redrilled in the past if threads were damaged.

A decent 8mm flare spanner is handy for working on the hydraulics, if you don't want to sacrifice a pipe to remove the fitting.
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Re: Rear Brake Line Replacement

Post by panky »

The spanner will be need to tighten the new fittings up anyway so good idea to have one available.
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Dytie
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Re: Rear Brake Line Replacement

Post by Dytie »

Cutting the brake line and using a socket to undo the fittings is a great idea. I was planning on using a pipe spanner but there’s less chance of rounding anything off with a socket.

Replacement brake lines arrived from Pleaides today. I’m not sure I’ll get around to fitting them over the weekend as it’s too cold to be working outside on cars atm. If conditions allow, I may get the wheels off to soak the bleed nipples in plus gas.

So in terms of getting the car in the air, the easiest method is to put the suspension on high, reverse up some ramps, lower the suspension to depressurise, jack up the car further to allow removal of ramps and wheels, and place axle stands under each side of the rear axle.

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Re: Rear Brake Line Replacement

Post by rutter123 »

Yes that's the plan. I'm lucky enough to have some truck stands which (with the car in high reversed up ramps) they sit about an inch below the rear beam and drops down nicely onto them without using a jack.
Leave the car in high position whilst you remove the rear wheels or you won't get em out.

Beware of pipe fittings snapping off, it does happen if they are particularly rusty, and you really don't want that.
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Re: Rear Brake Line Replacement

Post by white exec »

To prevent rounding of these small hydraulic unions (and bleed screws), use a "single hex" flare nut spanner (well worth buying a set, say from 8mm upwards - plenty on Amazon), or single hex sockets (eg the air wrench type). These are better than the usual bi-hex (12-notch) spanners and sockets, as they will be less likely to damage the metal. Above all, avoid using open-ended spanners!
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Dytie
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Re: Rear Brake Line Replacement

Post by Dytie »

Thanks for all the replies. I managed to replace the leaky rear brake line however now I can’t get the wheels back on as the gap between the hub and the wing is too small? I started the car, flipped the suspension into its high setting and was expecting the rear axle to drop or the rear of the car to rise (car is still on axle stands).

I haven’t bled the wheel with the new brakes line yet, so do you think that could be it? Any ideas or suggestions gratefully received.

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Re: Rear Brake Line Replacement

Post by Jaba »

You need to bleed that new line, and very possibly the other side too. The rear suspension and brakes share the same fluid supply and the bleeding has to be done anyway with the wheel off so easily done now.
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Re: Rear Brake Line Replace

Post by white exec »

Bleed with hub hanging, engine running, susp set on highest, and light pressure applied to the brake pedal (a length of wood between brake pedal and seat front works well).

This makes bleeding a one-man job: just open a bleed screw (usual clear tube and a jar) and fluid/air will flow out continuously. Recommended order is RR, RL, FR, FL, if doing all four. Keep an eye on the reservoir level, or throw an extra 1L in before starting to bleed. Over-filling the reservoir by this amount isn't a problem.
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Re: Rear Brake Line Replacement

Post by Dytie »

Hmmm… topped up the LHM tank, placed suspension in high setting with engine running and piece of wood wedged between the seat an the brake pedal, released the bleed valve but nothing’s coming out. Even tried jacking up the rear swinging arms as I’d read it opened the brake valve. Any ideas what else I could try?

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Re: Rear Brake Line Replacement

Post by white exec »

Should work... Putting the suspension on highest has the same effect as applying a heavy load to the rear suspension.
Silly thought: take it that the pressure relief bolt (on the Accumulator/regulator) has been shut?

Are other things responding normally...
...car rising/sinking
...brakes operating
...steering getting power assistance?
Just wondering whether there's a major airlock in the system...

Is the pump pumping?
If it gets airlocked, you can sometimes kick it into action by standing on the brakes firmly, and turning the steering wheel from lock to lock.
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