The brake pipes on T-Types were originally made from steel and later replacements from copper. No doubt some cars still have their original brake pipes or copper replacements today. Steel pipes are liable to corrosion, of course, and it is now widely recognised that copper pipes have a tendency to fracture over time as a result of metal fatigue. So if you are rebuilding a car or refurbishing your brakes, it makes sense to use the best material available today, which is Cunifer tubing. Cunifer gets its name from the chemical symbols of the metals of which it is an alloy, namely, copper (CU), nickel (NI) and iron (FER).
Cunifer tubing is widely available on both sides of the Atlantic. A Google search will reveal plenty of sources. It is available in 4.8mm, 6.35mm and 8mm diameters. 6.35mm is correct for the TABC, being the metric equivalent of the ¼ inch tubing used originally and 4.8mm is correct for TDs and TFs. It is typically sold in 25 foot lengths, which is ample for a T Type.
Whilst ordering the tubing, it is probably a good idea, (but not essential), to order a new set of nipples. Alternatively, these can be reclaimed from the original brake pipe set. The correct size for TABC is ¼ inch x 7/16 UNF and 3/16 inch x 3/8 BSF for the later cars. 7/16 inch nipples are available with 7/16 or ½ inch AF (across flats) heads. The latter perhaps allow more purchase when tightening. You need 12 nipples for a TABC and 16 for the TD/TF. Whilst ordering material have a close look at the date code printed on your rubber brake hoses. If your hoses are any more than ten years old you may want to consider replacing them at the same time. There are three hoses on T-Types, two at the front and one at the back, but they are not the same across the range of cars. The least expensive source of these flexible hoses is, in my experience, the Octagon Car Club who will sell you a set for little more than some suppliers charge for one! If you live in North America and Octagon won’t sell to you for fear of litigation I can only apologise on their behalf.
If you have a TABC the final item on your shopping list will be the wire to make the armour coils that slip over the tubing to protect them from potential damage in their vulnerable position under the car. Most commercially available brake pipe sets that I have seen for the TABC use wire that is too thin, the turns are spaced too far apart and the coils are never long enough to replicate the original arrangement. All of the pipes on the TABC, except the longest one that connects the three-way union at the front of the car to the flexible hose at the rear, have armour covering. Most are completely encased, and one is encased for part of its length. Fig 1 shows a section of original pipe encased in its armour coil. This is a picture of John James’ TC0750, ‘The Vicar’s Car’, before restoration began. It shows the section of pipe that crosses the brake pedal shaft on the driver’s side of the chassis.
Fig. 1 An original brake pipe and armour coil on ‘The Vicar’s Car’, (complete with 60+ years of accumulated dirt, oil and no doubt some corrosion too).
It took me a long time to find a suitable source of wire to make these armour coils. Stainless steel is the obvious choice to avoid the tendency of plain or plated steel wire to rust, but it needs to be soft enough so that it can be wound easily into the spring-like coils that slip over the pipes. Wire from most sources in the thickness required, 1.2-1.4 mm, (0.048-0.056 inches) is too hard to allow a tight coil to be made using a realistic tension. Eventually I hit on the idea of using ‘tying wire’, which is used in the construction industry to tie reinforcing bars together before they are encased in concrete. I have found this to be ideal. It is sold in two kilogram reels, and comes in a handy cassette dispenser, designed to be worn on a belt around your waist, so leaving both hands free during the winding process.
These cassettes can be bought from the manufacturer Reelfix from their Ebay store: see this link.
Fig. 2 The Reelfix Wire Cassette
I wound coils for my TC using a lathe and a mandrel consisting of a piece of ¼ inch piano wire, about a metre long. If you don’t have a lathe I’m sure your local machine shop will wind the coils for you.
Start by making a means of fixing the wire to the mandrel. This can be as simple as several turns of masking or gaffer tape, or a more elaborate fixture as shown in Fig 3. Fit the mandrel into the lathe chuck, with about 150mm protruding from the chuck, the remainder of the mandrel being inside the headstock as shown in Fig 3.
Fig. 3 Winding the Armour Coils
Now fix the free end of the wire to the mandrel, engage backgear, reverse and the slowest speed. Using a pair of tough leather gloves grip the wire tightly, and turn on the lathe. As the wire is pulled from the cassette keep it under tension and guide it from right to left to form a spring-like coil with adjacent turns touching. When the coil has progressed to within about 10-20mm of the chuck, stop the lathe. Release the chuck, and pull out the next 150mm of the mandrel. If any more than about 150mm of the mandrel is exposed at a time there is a danger that the mandrel will bend due to the tension required to form the coils. Repeat the winding process until you have produced a coil of sufficient length as described in the table on the next page. Beware when cutting the coil from the remainder of the wire in the cassette as the spring will uncoil somewhat as the tension is released. Hold the end of the wire as it is cut and let it unwind slowly to minimise this effect. This slight unwinding is essential to allow the coil to be removed easily from the mandrel and allow it to be fitted over the brake pipe. Fig 4 below shows a length of armour coil taken straight off the mandrel before trimming to length.
Fig. 4 A Length of Armour Coil Ready To Be Trimmed To Length
With a little practice you will be able to produce perfect coils in no time at all. Once you have gained confidence you can increase the lathe speed to quicken up the process. It is a wise precaution to wear safety glasses during this operation, as it is when using any machinery. Make the coils a little longer than specified so that the start and finish can be trimmed off. Keep adjacent turns touching so that the coils can be teased out later as they are fitted to the car. The coils cannot cover the whole length of the pipe with adjacent turns touching because a gap is required at one end of the pipe for the flaring tool to grip it whilst the second flare is formed. This gap is covered by stretching the coil after the second flare is formed and is unnoticeable in practice, except possibly on the shortest pipe on the TABC, which connects the rear three-way union to the driver’s side rear brake cylinder.
Now that you have perfected the production of armour coils it is time to try your hand a pipe flaring. T-Type pipes use double flares, so called because the flare is formed in two separate operations. An example of a double flare is shown in Fig 5 below.
Fig. 5 A Double Flare formed on a piece of ¼ inch tube.
Again it is a good idea to practice on a short length of tube to gain confidence, before making the actual pipes that you will fit to your car. It is not difficult; it is just a matter of gaining confidence, which comes after a couple of attempts.
There are many flaring tools on the market which range in cost from about £25 for a basic tool, up to around £100 for a ‘professional’ version. I have used a model sold by Automec, whose list was included along with Brian Rainbow’s article in August’s TTT 2 (Page 19). The tool is shown in Fig 6 below:
Fig. 6 The Automec Flaring Tool suitable for both 4.8 and 6.35mm tube.
Again, the internet comes in handy here, this time in the form of YouTube:
Above you can watch a video demonstration of one of the many types of double flaring tools. It gives you an idea of how easy it is to make a perfect flare.
Now for some tips – I learnt the hard way:
• When making brake pipes it is a good idea to start with the longest one first. That way, if you make a mess of it, you can cut off the flares and use the remaining tube to make the next longest pipe. If you start with the shortest pipe and make a mess of that, it is scrap.
• Another useful tip is to make absolutely sure you have the armour coil and both pipe nipples (the correct way around) on the tube before you form the final flare. It is not easy to fit either the armour or the second nipple once the second flair has been formed! If you do forget (and I have to admit to doing so myself) again you can cut off one of the flares and use the remaining tube to make the next shortest pipe.
• Note that as a result of forming the flares at each end of a pipe the tube ‘shrinks’ in length by a few millimetres each time. When making your practice flare, measure the length of the tube before and after forming the flare(s) and note how much it has shrunk. Add this amount to each pipe to obtain an accurate finished length.
• Finally, it is important to remove all the burrs from the cut end of the tube; otherwise you won’t get a good flare (see next para for advice on how to do this).
• This is the method I use. Firstly cut the tube to the length specified in the table*, plus a shrinkage allowance determined by the tool you are using (see note above about calculating the shrinkage). Use a fine-toothed junior hacksaw, keeping the cut square to the tube end. Then with the tube horizontal, file the cut end with a fine file to remove the saw marks and the burrs from the cut. Then de-burr the internal wall of the tube with a drill bit.
• Finally suck out any debris left inside the pipe with a vacuum cleaner. This should be done from the end of the tube being worked on, to avoid drawing the debris along the full length of the tube where some of it could remain.
* Table follows.
Table 1: Brake Pipe Lengths for TABC
|From – To
|Front 3-way union to rear hose
|Master cylinder to LH hose
|Front 3-way union to RH hose
|Rear 3-way union to RH rear wheel cylinder union
|Master cylinder to front 3-way union
|Rear 3-way union to LH rear wheel cylinder union
NB: LH & RH as viewed from the front of the car.
* Only the RH portion of this pipe from the wheel cylinder union to the fixing clip is fitted with an armour coil. The section looping over the differential is unprotected.
Before fitting the armour coils and forming the second flare it can be helpful to form the bends in the end of each pipe that is to be bent around the tightest radius. This is generally the ends of the pipes that connect to the three-way unions or the rear wheel cylinder unions. For really tight bend radii use an external bending spring to stop the pipe collapsing as it is bent. The larger radii can be formed easily by hand after the pipe is complete. This applies particularly to the TABC, which uses the larger diameter tube. The smaller tube used on the TD/TF is much easier to bend as they are fitted. Don’t bend any of the pipes closer than about 100mm to the end before the final nipple is fitted because the nipple will not fit onto a curved pipe. Fig 7 shows an example of a finished pipe with nipples and armour fitted.
Fig. 7 A finished pipe complete with armour and nipples.
Making your own brake pipes is a satisfying job and can be less expensive than buying commercial brake pipe sets, especially if you can borrow or hire a flaring tool. You will know the tube is indeed Cunifer, there is no debris left in the pipe to damage the delicate brake cylinder seals and the coils look just like they did when your car came off the end of the line in Abingdon all those years ago.
Please note: Brake pipes are a safety critical part of the braking system of your car. Do not attempt any work on your braking system unless you are competent to do so. Check for leaks after bleeding the brakes before you use your car on the road. If you are unsure always seek professional advice.
ericlembrick ‘at’ gmail ‘dot’ com
Ed’s Note: Thanks Eric for a really useful article and the links you have given are particularly helpful.
Whilst we are on the subject of brakes there has been some off-line correspondence arising from Brian Rainbow’s article in the August issue (Issue 1). This has centred around the mixing of Glycol (DOT 3, 4, 5.1) and Silicone (DOT 5) brake fluids, and the use of methylated spirits for cleaning the system.
Who better I thought to seek advice than from Barrie Jones, TD/TF Technical Specialist for the ‘T’ Register!
Barrie commented as follows:
“There is a lot of anecdotal evidence that old rubber cups impregnated with DOT3 or DOT4 can swell up if they come into contact with DOT5. Therefore, it is important to replace them when converting to DOT5. Even then (according to my friends at Nelson Brovex*), you run the risk of slight swelling.
Five years ago I converted my TF from DOT3 to DOT5 as follows:
1) Flush out the entire system with denatured alcohol (methylated spirits) in order to remove all trace of old brake fluid.
2) Blow out the denatured alcohol with compressed air, leaving the system open to the air for several hours so that any residue can evaporate
3) Strip the entire system down, replacing every rubber component
-Master cylinder cups
-Slave cylinder cups
-Flexible brake hoses
4) Fit a slightly thinner main cup inside the master cylinder
My TF tends to hibernate over the winter, and every spring I had the ritual of `freeing off’ the brakes. Since converting to DOT5 I have never had any problems with corroded pistons.
It really was `fit and forget’.”
*Brovex Nelson is a supplier of automotive components (including brake hoses and brake cylinder repair kits) based in Camelford, Cornwall.
Ed’s Further Note: If you’ve renewed the brake pipes on your car you will probably have renewed or overhauled the wheel cylinders and master cylinder.
A couple of years back when I was plagued with leaking wheel cylinders on TC0750 and a wheel cylinder repair kit did not do the job, I decided to buy some new bronze ones from C & C parts in The Netherlands. You can also buy them from the MG Octagon Car Club.
The original wheel cylinders were left on the shelf in the garage (never throw anything away!) and it occurred to me that this was really a wasted resource, since if I was to get them refurbished, it might help somebody else. So I boxed them up and sent them to Past Parts in Bury St Edmunds, Suffolk – Telephone: +44 (0) 1284 750729. They arrived back in ‘as new’ condition. Within a matter of weeks an ‘e-mail pen friend’ of mine in Poland needed some for his TC so I was pleased to be able to help.
The service provided by Past Parts was very good and the price for refurbishing four wheel cylinders was £185 which included the postage for getting the cylinders back to me. The postage for sending the cylinders for reconditioning was around £9.
So that’s most things sorted with the notable exception of brake drums. Cast iron brake drums for TA/B/C machined from a modern drum still in production (a Nissan Vanette) can be bought from Brian Thomas of Engineering Solutions in Bexley, Kent. These are the same drums as advertised in Issue 1 (August 2010). Brian’s website can be found at engineeringsolutionsuk.com. Each drum costs £85, which includes an amount for postage. Brian also does VW steering box conversion kits, so he’s a handy chap to know.
Up to now, brake drums for the TD/TF (disc wheels) have been unobtainable. A while back I made some enquiries about getting some produced but there weren’t any manufacturers ‘busting a gut’ to take the job on. I hear that the MG Octagon Car Club are looking to get both TA/B/C and TD/TF drums produced. Those of you who are Octagon members will already know this; those who aren’t will learn of developments through TTT 2.
In the February issue of TTT2 there will be an article about skimming TD/TF brake drums and fitting oversize brake linings.