How To Guide Brake Pipe Replacement Procedure

[t-tony]

Part One - Tools Required

To make up your own brake pipes you will need a Flaring tool which is used to make the "flare" or the sealing end of the pipe. To cut lengths od brake pipe you need a mini tube cutter which produces a "clean" cut which in turn makes a better joint.

Special spanners are very useful for tightening/loosening brake pipe unions. These generally have wider jaws and are less likely to slip or round off the unions. As far as I'm aware for a BMW you will need an 11mm and a 13mm spanner.



A bar to hold the brake pedal down is a very useful bit of gear too, not essential but saves on fluid leakage when the old pipe is removed.


Also a tool to aid in the bending to shape of new pipes is extremely helpful to avoid "kinking" the new pipe where a sharp bend is needed

 

[t-tony]

Part Two - Removing the old Pipes

1. Jack up car and remove the wheel where the pipe is needing to be replaced. Apply the pressure bar to the brake pedal.


2. Cut off the old pipe right next to the unions, then remove the old unions from the hose ends with a socket and ratchet. If you are disconnecting the pipe at a "joiner"(male and female unions screwed together) it is best to use 2 spanners to loosen the joint before cutting the pipe off.




3. Measure the new pipe by holding a piece of string alongside the old pipe adding the length of the 2 unions+13mm. Hold the string to the new pipe and cut a piece off using the mini cutter.

 

[t-tony]

Part Three - Making the New Brake Pipes

Here you need your flaring tool to fashion the sealing ends onto the ends of the brake pipes.

A tool like the one shown can be bought off eBay for £10, mini cutters £5 and a bending tool about the same. So for a little outlay you can make your own pipes. Be prepared for a little trial and error before you become proficient in the art of making pipes.

1. Place the tool in the vice as seen and hold the pipe to be flared into the 3/16" jaw (the smallest one) allowing as much to protrude to be level with the shoulder of the "Die" as in the picture. Turn the Die round and put the centre into the pipe and assemble the tool as shown , then wind the clamp with the Tee bar until the Die is compressed up to the bar. If a double flare (convex for female unions) is needed you simply use the tapered end on the forming tool to counter sink the 1st flare whilst the pipe is still clamped in the bar. The tool comes with easy to understand instructions.







2. Slide the required unions onto the pipe before flaring the other end of the pipe. A very common mistake requiring the end to be cut off and re made is not putting the unions on or not the right way round.

3. Bend the pipe to the required shape. If a very tight bend is needed as in the picture you can use a bending tool like mine (a Girling service tool). The pipe in the picture I bent with my thumbs, if you don't have strong hands you may not be able to do this and the bending tool is essential to prevent kinking of the pipes.

 

[t-tony]

Part Four - Joining the Brake Pipes

Joining brake pipes is a simple job. Many cars have joints which consist of a male and a female union being joined together.

What you need is a single (convex) flare on the male union and a double (concave) flare on the female union.

Ideally the male union needs to threaded all the way to the end and not have a plain shoulder as in the pictures of the 3 unions on the red box. You can see in the pictures that the union which is threaded right to the end has at least 1 full thread more inside the female union, giving a better seal in my opinion.
The one threaded right to the end is usually found on Japanese and Asian cars rather than European cars, but very handy to have a few in the tool box.







Alternatively you can use a purpose made joiner which takes a male union from both ends.

You can see a male/female joint on the car I did the other day in the last picture.

 

[t-tony]

Part Five - General Tips on Brake Pipe Replacement

1. Steel - like the original will corroded if not treated. Hardly ever used for replacement pipes.
2. Kunifer - a cupro-nickel pipe which is slightly softer than steel and slightly easier to work with but difficult to get tight bends without bending tools.
3. Copper - much softer and easier to work with including flaring joints. Down side is if you need to take the joint apart it will often twist the pipe before the union spins on the pipe itself. If it is going on an part which may need dismantling I would use Kunifer.

Always be careful to route the pipe correctly in the way the old pipe was and ensure it is clipped back in it clips to keep it secure to the car.

Always apply pressure to the foot brake after bleeding the system and check for any leaks.

 

[jonco]

Thanks @t-tony. Good info on all brake pipe posts. Could do with all combining and putting in knowledge section. You had nothing to do last night then bit quieter than last Saturday.

 

[zedonist]

Brilliant tony what size tube snd fittings are required on the Zed, also does the Zed use double flare?

Thanks Rich

 

[zedonist]

Can I take it a vice is needed also Tony?

 

[GazHyde]

@t-tony - as requested I've been through and edited them for you Also merged them neatly in to one post with five sections to make for easier reading! Let me know if I have any pictures in the wrong order!

 

[t-tony]

H

Brilliant tony what size tube snd fittings are required on the Zed, also does the Zed use double flare?

Thanks Rich

Hi Rich, you will need 3/16" tubing and in the main as a general rule male unions go with single flares and female ones use double flares but always check what is on the old unions first. You don't have to use a vice as you can use this tool "on the car" to join pipes where only part of it is damaged, corroded etc. Again you do need a strong grip.
Anything else you need to know give me a shout. I may have missed something as my head was buzzing by the time I finished this last night.

Tony.

 

[pingping010101]

Is this process the same for power steering pipes?

 

[t-tony]

Basic principal is but you need bigger stronger tools for the larger bore copper or steel pipes.

Tony.

 

[Faheem]

Excellent guide.... if only I had read through this carefully before.

Unfortunately I'll have to remake all my brake lines. I've used a double flare (2 stage) on all my fittings rather than the single stage or bubble flare that BMW use.

Having done a bit more research, I have read supposedly that I won't get a proper seal using the double flare.

I flared the lines after watching several YouTube "how-to" videos, and in all of them the advice was to use two stage flare - which unfortunately won't work in a BMW- is that right @t-tony?

Here's a picture showing the differences, just as an fyi for anyone else.

Double Flare fitting ^

Bubble Flare fitting ^

Should only be 4 lines to make though

Forgive me if this is all common knowledge but it wasnt obvious to me and it might help others from making the same mistake.

 

[t-tony]

To make all joints you HAVE to make the "bubble" or Convex Op 1. flare first, then if you need the concave or Op 2.flare you use the other die.

You may not even have to remake the pipe, you might be able to just cut off the flared end and remake the flare you need.

There have been cars in the past which have had both types of fittings on the same car. One that springs to mind would be the older Rover/Honda models which had Imperial thread on the body end and Metric at the wheel cylinder. You have to look at what you take off and replace like for like.

Tony.

 

[Faheem]

Cheers Tony, I followed the process that you had advised for the union fittings but for some reason i didn't think that would apply for the other fittings so ended up doing the double flare on all the other ends

I'd rather i found out now and corrected it rather than a few months down the line.

 

[Matt Barnes]

Afternoon all.... tempted to do this myself after buying new calipers for the front and not being able to free the flexi hoses from the old calipers (WD40 and blow torch having zero effect). I see the unions are 11mm and 13mm ?... is there anything special about them as if I try and order 3/16th pipe with unions from various sites, it always says, not compatible with BMW Z3 1.9 140HP

 

[t-tony]

Again, to loosen the hoses from the callipers you need a pair of flat jawed mole grips. At least a 10" pair for leverage.

The ones on the right have flat jaws. The ones with curved jaws have very limited use.

Tony.

ps. The pipes may have different flares on the ends. Get some pipe and unions and make up pipes.

 

[t-tony]

@Matt Barnes the unions you need are the ones on the left in this picture. They are 10mm.

Then make the flares as required.

Tony.

 

[Matt Barnes]

Thanks Tony I'll give it a go..I've resigned myself to losing the Flexi as I think too much damage will be done. I might try the top end after I soaked in WD40 for a week .. I will get the flaring kit though!

 

[t-tony]

Good luck and please shout up if I can help.

Tony.