Mini Workshop - Brake and Clutch pipes
First, and most important - IF IN DOUBT - DON'T - the safe functioning of your brake is absolutely critical, if you are not confident in your ability to make your own brake pipes then buy ready-made items from your local motor factor.
The brake and clutch pipes on a standard Mini are made from 3/16" steel pipe, plated with a corrosion resistant coating. Despite the coating, they do rust and should be checked regularly.
Replacement pipe may be made from a copper/nickel alloy which, in addition to not rusting, are also a lot easier to bend to shape.
There are two types of fittings for the ends of the brake and clutch pipes; male (left) and female. The male fittings are used for master cylinders and connectors, the female for attaching flexible pipes. For earlier Minis, both these fittings had a 7/16" UNF thread, with later cars using a metric equivalent.
Each of these fitting types require a different shape pressing onto the end of the pipe, the shape provides the seat that seals the pipe to the master cylinder, T-Piece, etc, and it is therefore very important that this is formed correctly.
There are a number of tools available on the market, they all work on the same principle of using a clamp to hold the pipe firmly while a shaped die is pressed onto the pipe end, forming it into the desired shape. For a male fitting the left hand die is used, whereas a female fitting requires a two stage operation; first the left hand die is used to create the convex shape, then the right hand die is used to reform the end into the concave shape. The pipe must not be removed from the clamp between these to stages.
If the formed end does not look symmetrical, scrap it and start again, the importance of getting this bit right cannot be over emphasised.
The pipe is supplied in a coil, and the temptation is just to pull out as much as needed, and then fit the ends. This leads to very unsightly kinks in the longer runs of pipe. If you hold the pipe against a straight edge and roll the coil along, the end result is a lot more professional looking.
Pipe cutters are readily available from plumbers merchants and DIY stores, they are not expensive and are strongly recommended as they cut a square end to the pipe. It is possible to use a hack saw but if you don't get the end square, the joint will be malformed. Don't be tempted to apply too much pressure to the blade, this will tend to swage the end of the pipe which will affect the shape of the finished end.
Use the blade in the cutting tool to clean the cut end, being very careful not to get swarf into the open end. The pipe may now be clamped in the tool and the required end formed, before doing that slide the fitting over the pipe - sounds obvious but believe me, it is very frustrating to find that having created a perfectly formed end, you have to cut it off because you forgot the fitting.
With the pipe suitably terminated, it is time to bend it to shape, the copper/nickel pipes can be bent by hand, but a simple pipe bending tool makes a much neater job. If you don't have a bender, clamp a suitable diameter socket into the vice and use this as a former.
For the more intricate shapes, a length of heavy garden wire is most useful, not only can it be useful as a template for the shape, but it also provides an accurate length for the pipe to be cut to.
When the pipes are fitted, they should be clipped into place at frequent intervals to prevent them being caught and damaged or vibrating, which may in turn lead to metal fatigue.
Once again - IF IN DOUBT - DON'T