Brake pipe replacement

[white90]

The following is how to replace a corroded brake pipe and make a duplicate - using a brake pipe flaring tool.

Brake pipes are usually quite fragile by the time they have to be replaced - the ends are quite often seized, and a spanner just rounds them off - requiring mole grips or other drastic measure to remove them. Bleed nipples snap off, and then the cylinder has to be replaced as well, so quite a bit of care is required to do this job.

The vehicle is an early 90, and has failed the MOT. Some MOT stations just list the failed item on a failure sheet, and some mark the fail with chalk/crayon (usually yellow), as in this picture.

This is the drivers side rear brake pipe - it runs from a T-piece that's bolted to a bracket on one of the diff housing bolts.

Runs across the back of the axle tube, where there's one pipe clamp, and then to the rear of the brake back-plate to the wheel cylinder.

Special tools required are a flaring tool - they are not very expensive to buy, and although there are many different types - they all basically do the same thing. This is my portable one - it does just the two different ends for 3/16" copper or steel brake pipe - single flare (the end looks like a trumpet), and double flare (the end looks like the head of a mushroom). You must always make up the same end as the old pipe to avoid leaks/possible brake failure.

This tip makes the single flare (or trumpet)

Double flare (or mushroom)

A packet of brake pipe -25 feet of it usually.

Place a clamp on the flexi pipe to prevent the system from emptying when the pipe is removed. You can buy a proper pipe clamp that exerts just enough pressure to close the pipe without damaging it. Careful use of mole grips is just as good.

Pipe ends are usually 11mm, so an open ended spanner that's a good fit. It the spanner feels like it's going to slip, then stop and resort to a pair of mole grips. If that doesn't work either - cut the pipe where it enters the fitting and use a socket.

The single pipe support clamp normally shears off when you try to undo it. If this happens you will have to use cable ties to secure the new pipe.

The bracket on the diff casing that supports the T-piece is easily bent, so support it with a pair of mole grips while undoing the pipe end.

If you're lucky, the pipe will come off in one piece.

Carefully measure the length of the old pipe - add a small amount to be on the safe side.

Make sure you have the right pipe fittings (these are 10mm male). Copy the shape of the old pipe, taking care when making bends to not kink the pipe (I use a 12mm socket to do this). Put a new pipe end on before making the end up.

New pipe all finished and compared to the old one.

Place new pipe in position - make sure the pipe ends are lined up in their respective holes - the thread is fine and can easily be stripped. Don't over-tighten the ends either the copper pipe is soft and will seal with ease.

Bleed the system as normal (both sides at the rear) press and maintain heavy pressure on the brake pedal for about a minute, and then check for leaks - tighten any joint a small amount more if necessary and re-check.

Few things to remember:-

Make sure you make the same pipe end as the old pipe.

3/8" and 10mm pipe ends have a very similar thread, so make sure you have the correct ones - you can use the old ones at a pinch - providing they are not damaged.

Take care not to kink the brake pipe.

Make sure the new pipe doesn't rub or vibrate against any other part of the vehicle - it could cause a leak at a later date.

Les.