Charlie's Shed - Cables & Cable Making

Updated - first published February 2014

This is the section where we deal with those cables that you oil regularly, that operate your clutch and your front brake. They are an important part of your biking experience, not only for your safety but also to make the experience a pleasant one – there something rather magical about you & your bike cruising smoothly along a sunny lane, with everything operating as it should. One of your main connections to your bike is through those control cables:

Cables & Uses

Since the dawn of the bicycling era we have had the Bowden flexible cable. Your typical old motorcycle will have several – for the front brake, the clutch, the throttle – and maybe for the back brake, an air slide, a decompressor and the magneto as well.

You may have noticed that these cables are not identical – in fact there is a whole variety of components used in control cables throughout the biking world. Like many other facets of life, cables have their own jargon. Here are the keywords:

You might recognise this as something like a Bantam clutch cable – though Bantams have the adjuster mid-way along the length of cable, not at one end.

Cables are manufactured from multiple strands of high-tensile steel wire, formed into a cable (i.e. twisted together in contra-rotating layers) provided with a compression resistant outer casing formed as a spiral of rectangular section wire, covered in a PVC or cloth sheath. The outer is finished with a pair of ferrules at each end, to protect the ends, and the inner is fitted with a pair of nipples, usually brass, to allow the handlebar lever or twist grip to pass the load into the cable, and the cable to transmit that force into the clutch, brake, or throttle slide.

Talking about loads, of course we realise that the load passed into a throttle slide is far less than the load that is required to bring a heavy bike to a stop with the front brake. So, we need several different cable sizes to cope with these loads – we don’t want to operate the tiny throttle of a BSA Bantam with a cable suitable for the rear brake of heavy bike like a BSA A10, because it would be way too stiff and the friction alone would probably stop the throttle closing.

So there are several cable sizes in use:

It’s useful to note, when you are buying cable components that several of those inner wire diameters are similar – 0.062” is not so very different from 0.075”, so be careful when measuring!

When you have bought your inner wire, store it carefully. One of the key elements of successful soldering is cleanliness - solder will not 'take' to greasy wire or to wire that has been out in the weather for a while. The inner cable should be free of grease and the plated wires should be shiny - dull corroded wires may not solder at all.

Outer Casings, Nipples, ferrules, inners etc.

So, to help you decide which components you need, here are some tables identifying the various parts:

Inner Cables & Ferrules

Here are the dimensions for the corresponding casings & ferrules for those cables listed above:

Nipples  

Occasionally you'll find a nipple application that you can't buy, in which case those of you with a lathe and some brass bar can make them yourselves. Here's how I do it, in the post 'Free the Nipple'.

Sometimes, nipples are fitted with plastic sleeves to reduce friction. These can get mangled but you can make a sleeve (here's how I do it) to replace them:

Buying Parts

There are a few suppliers offering cable making parts shown on another page. Shop around though, since nipple prices seem particularly variable. It is probably wise to buy your inner cable and outer casing from the same vendor.

Making up a cable

You’ll need to determine some details of the installation before you start on making up your cable. First of all, check out the cable size using the tables. Determine the length, during ‘Routing & Laying Out’. Look at the sizes of the appropriate ferrules – you must make sure that the ferrules fit inside the adjusters on the handlebar levers, brake plates or wherever or inside the levers themselves.

Then, take a look at your nipples – use the tables to determine what you might need, and then look at the handlebar levers, the brake arms or the clutch arm – whatever parts you are trying to control, to determine what nipples you need.

Note that some nipples will only fit certain sizes of inner cable, and that the handlebar levers you have may be damaged – bent levers result in poorly fitting nipples or ferrules.

Routing & Laying Out

Now it is research time. Try and get a look at some other machines, or pictures, to get an idea of how the cable was originally laid. Think about whether the cable routed behind the headlamp, in front of the yokes, down behind the fork leg or in front of the fork leg, which side of the fuel tank it went; under the engine, over the engine etc.

Keep it away from hot parts like the exhaust or cylinder head; make sure that there is enough length for the bends to be long and sweeping – with a large ‘bend radius’, and check that out with the steering in the straight ahead, full lock left and full lock right positions. Sweeping bends and good routing are the secret to smooth acting, long lasting cables.

Try and determine how the cable was tied to the frame and whether any guides or clips were originally used. Once you have this figured out, run a length of your chosen outer casing along the route and have a think about it. When you are happy, you can cut the outer casing.

Cut the Outer Casing

The outer casing is made from a rectangular section steel wire, hardened to provide a strong, flexible and incompressible outer casing. It’s covered with PVC to provide weather protection, retain lubricant and to make it look pretty (these are available in a variety of colours for all you Ariel Arrow sports riders).

All this makes them a little tricky to cut. Good side cutters or a sharp chisel are usable, but cannot provide a square end; not strictly necessary, but if you want it, and a square end allows the ferrule to fit over more of the casing and to be retained more reliably, you can use a cutting disc in a Dremel or similar tool. This results in a neat square end, and the PVC, which will have melted somewhat can be cleaned up with a sharp knife.

Ferrules

The ferrules are often nickel plated brass or steel. They vary somewhat from supplier to supplier and may be brass and hard; or steel and soft. They should be a sliding fit over the end of the outer casing but if slightly tight their fitting can be aided with a little detergent or something more readily available (I usually use a bit of saliva! Good lubricant for rubber, saliva) they should not push the PVC out of shape when they are fitted.

If they are tight, you might choose to leave them as they are; you can tap them in one place with a dot punch; you can crimp them with pliers. After I had made a few cables, and never been very satisfied with any of these methods, I made a simple swaging tool from two pieces of ½” square bar. The bar has a variety of holes, sized to suit the OD of the ferrules, less 0.5 mm. Therefore I have a series of stepped holes – the ferrule OD, and the ferrule OD less 0.5mm.

You will notice from the picture that this swaging tool, made from two bars, has the holes drilled such that they can be split. The modus operandi is to place the ferrule over the casing, and then place the ferrule in the tool such that the bottom 1/16” or so of the ferrule is gripped by the smaller of the two diameters in the hole.

The bars are then squeezed in the vice, and the ferrule is swaged such that it grips the cable outer casing. This works with all ferrule materials, but the harder brass ferrules are inclined to split when swaged. The steel ones work beautifully though.

First Nipple

Which nipple you fit first depends a bit on the installation. The trickiest part of making a cable is cutting the inner to the right length, at the second end. If you mess it up, the inner might be too short – in which case you have to start again; if you make it too long you just have to re-solder. So, I like to fit the most accessible nipple last. Usually this will be the handlebar end, but in this example I am making a front brake cable, which is very accessible both ends.

Fit the first nipple over the cable end, with the belled-out side away from the inner case ferrule. It should be a nice sliding fit on the inner cable.

The next step is to prepare the inner cable for soldering. It goes without saying that these control cables are vital for your safety and proper preparation of the cable, proper soldering (including selection of the solder) is vitally important!

There are two types of soldering technique to consider – hard soldering and soft soldering. Hard soldering involves the use of a solder containing a high proportion of silver, and temperatures up to 750°C. This involves the use of a hot gas flame and incurs the risk of annealing the cable (since most hard solders melt at a temperature higher than the tempering of the wire in the cable), leading to the possibility of the material yielding and the cable stretching - or, if you were foolish enough to quench it, the wire will harden and break potentially with catastrophic results.

Soft soldering on the other hand involves the use of solder containing various proportions of tin and lead, and temperatures of below 400°C, which will not risk annealing the steel wire. Soft solder can be heated using an electric soldering iron or a solder pot, and the temperature will be easily controlled avoiding the risk of oxidisation or weakening the wire.

Soft solder is made in a variety of ‘recipes’ for various uses:

You will note that the solders listed vary in their strength according to the constituent components. A Lead free Tin/silver alloy is the strongest and therefore the most suitable for our purpose these solders melt at 250-300°C, suitable for a conventional soldering iron.

Solder is available in bars and wires, both with flux cores and without. I use non-cored wire solder, since I like to be able to control what flux I use.

So, you will need some flux. Metals at higher temperatures are even more prone to oxidisation than usual – so we need something to prevent oxidisation during soldering, otherwise the solder joint will be weak and will fail.

The impurities can be removed by mechanical cleaning or by chemical means, but the elevated temperatures required to melt the filler metal (the solder) encourages the work piece (and the solder) to re-oxidize. This effect is accelerated as the soldering temperatures increase and can completely prevent the solder from joining to the work piece. I like to use the liquid, Zinc Chloride based ‘Baker’s Fluid no.3’ for making cables, since it flows into the joint before any heat is applied and seems to be able to keep the join clean enough to ensure a successful joint every time. It's acidic, so you don't want to drop it on anything important (like a chrome wheel rim) and you will need to clean it off afterwards.

Now, onto soldering the first nipple. Again, we use our swaging jig which has a number of holes drilled through it of such a size as to grip the inner cable, without crushing it. In the top of each of these holes is a small well of larger diameter, used to form a ball, or birds nest, on the end of the inner cable. We start with the inner cable in the swaging jig, with a length equivalent to about four diameters of the cable sticking out above the well, the jig is clamped in the vice, and the inner cable is not going anywhere.

Using a punch, we tap down on the end of the inner cable, in order to divide the strands:

Having divided the strands down into the well, we take a pair of long-nose pliers which, together with a small hammer, we use to bend the ends of the strands back toward the centre, forming a ball:

This is where the strength of the cable assembly comes from. The ball prevents the inner cable pulling through the nipple, and the separated strands provide a hugely increased surface area for the solder to grip the wire, such that the tensile load in the cable is pulling on a ball of solder and wire which cannot pull through the nipple.

So, now we can remove the swaging jig and see that the wire nest fits nicely inside the nipple. We are ready for soldering. Hold the inner cable in the vice, gently, such that the nipple is pointing downwards. We want the solder to flow into the nipple and to stay out of the inner cable; otherwise the inner cable will become stiff and your lever action will be affected.

Lead rich solders are more reluctant to flow than tin rich solders. You may find it more effective to leave the ‘cup’ in the nipple upward using lead rich solder.

Dip the end of the cable and the nipple in the flux, and apply your soldering iron. It will take a while to heat the nipple up, but occasionally touch the wire with solder to see if it is hot enough. Remember that the work has to melt the solder – the soldering iron is used to heat the work, not the solder. If the solder will melt when it comes into contact with the nipple, then the nipple is hot enough. Proceed right away, since overheating will produce more oxidisation and will ruin the joint. Allow the solder to wick down the cable, filling up the birds nest in the nipple. Let it flow until it is about to drop out of the nipple, and you’re done. Leave it to cool - do not quench it and do not move the end, or you will lose the pool of solder within the nipple.

You'll find it much easier to solder the nipples if you have a solder pot, like this one:

The solder temperature is thermostatically controlled, so there is no danger of overheating the wire and the solder will flood the joint easily. Overheating will ruin the heat treatment of the wire - in the picture, I'm showing a clutch cable that has been rendered brittle by overheating the nipple. The cable fractured just behind the nipple, leading to a ride home changing gear very carefully and hoping for light traffic - the same breakage in a brake cable could have been very different. 

Once cool, clean all the flux off with water. Flux is highly corrosive and you don’t want damage arising from yet more oxidisation. File any excess solder away, and don’t worry if you file off the ends of some strands that are poking out.

Second Nipple

Once we have soldered the first end, we can fit the cable back on the bike. Make sure that all the adjusters are in their shortest position, and wind them out two turns. We are going to make the cable as short as possible but in the event that we are a little over-enthusiastic and we make it too short, we want to be able to loosen the adjusters more if it proves necessary.

Make sure you fit the cable in its proper routing and that the second nipple is properly located in the brake lever, carburettor slide or whatever. Now, you will need to have the parts in their operating position to get the inner cable length right – throttle twist grip rolled shut, throttle slide down; brake handlebar lever fully ‘off’, brake plate arm moved such that the brakes are almost on, but not biting. You want the brake, clutch or throttle in a position where a small amount of cable movement will have it operating with the adjusters wound ‘in’ otherwise the cable will be over length.

Mark the inner cable with a small piece of masking tape in the location you want it cut – but don’t cut it yet. It’s helpful when cutting cables if they are ‘tinned’, that is, if the strands are bound together with ½” or so of solder. Fit the second nipple and keep it out of the way with a piece of masking tape. Dip the end in flux, apply your soldering iron and when it is hot enough, touch the cable with solder and allow the solder to wick up the strands. Now it won’t unravel when you try and cut it. Use a sharp pair of side cutters or the Dremel cut-off wheel for this job.

Next, you can put the second end in the swaging jig and prepare the birds nest. Solder up the second end as before

Try it back on the bike, and use the adjusters to take up any spare length. If you have to unwind them considerably to get the brake, clutch, throttle or whatever workings correctly, consider releasing the second nipple and making the inner cable a little shorter.

Lubrication

Decent lubrication is vitally important to the operation and life of a cable, and to the pleasure of riding the bike. I use one of these clamp on cable oilers with WD40:

Cable Management

Several methods of cable (and we are talking both control cables and electrical cables here) management were used in the 1950’s & ‘60’s, some more obvious than others, some more effective than others.

We are all familiar with the modern nylon cable tie, but whilst this is available in a wide variety of shapes, sizes & colours it is not in keeping with a 1950’s machine. That said, I have several on my Bantam and very effective they are.

You will find pictures of these black rubber ties in the BSA parts book for the Bantam. Originally made from Butyl rubber, they perish very quickly and fall off; modern versions are made from silicone rubber and will survive oil, petrol and sunshine very effectively

They can be used in a variety of ways giving the opportunity to strap cables of various diameters to handlebars, frame tubes or mudguard stays, and are used by passing the ‘T’ end through the hole in the opposite end, trapping the cable against the frame or passing the T through the middle hole, around the cable, and then again around the frame and into the end hole, holding the cable away from the frame. This looks rather neat I think.

Ariel made use of some rather neat steel sprung cable clips. Here are two three-cable originals on my W/NG, retaining the rear brake switch wiring - there are further ones under the tank retaining the clutch, throttle & air cables. These clips are available in stainless steel for one, two or three cables:

Charlie's Shed - Ignition timing, and nearby jobs

Having fitted the new carburetter to the W/NG, I thought I would look over the ignition system before I shake it down any further. I was having trouble with the idle settings and I wanted to ensure the other maintenance settings were spot-on before I investigate the idle issue.

So this morning we are looking at ignition timing and some associated jobs. Our focus here is of course my 1942 Ariel W/NG, but the points are valid for any M01 magneto equipped bike - that's all the BSA pre-unit singles, Norton singles, Triumph singles & Royal Enfield singles.

Assemble tools

Get your tool kit ready. I always use the tools I have on the bike for jobs like this - next time you do it you might be grovelling about in the gutter, so it pays to make sure you have the right tools and that they fit the relevant fasteners.

For example, I once found my magneto spanner did not fit the points hexagon properly and needed to be opened slightly - I would not have been happy if I had discovered that out in the countryside, however sunny it was that day.

For this job, you will need a drip tray. The timing case will have some blow-by from the oil pump in it and you don't want it on the floor - you will slip in it when you are pushing the bike about, and then you'll drop the bike or yourself, or both, which will spoil your day.

Last thing is to put the bike in a high gear, so you can move the engine carefully from the rear wheel.

By the way, it is important that you do these steps in the proper sequence. Anything else is going to compromise the ignition timing and hence the quality of your spark.

Remove the spark plug

Use your tool roll plug spanner and tommy bar to remove the plug.

Have a look at the plug and deliberate over the state of your mixture, piston rings, and ignition timing. This one is verging on OK in my book - no oil, it's not burnt, but it is a little dark suggesting my mixture is a bit rich. I'll not worry too much about that since I have changed the carb and we are checking the ignition timing today.

Check the cable tension

The ignition timing is controlled by the advance lever on the left hand handlebar - at least it is on Ariel singles. Ariels use a 'tight wire advance' in that the lever is pushed away from you, pulling the advance cable to advance the ignition.

To start work checking the timing, we need to make sure this cable has a little slack in it. Look at the ferrule at the handlebar lever end and make sure it is seated properly in the lever:

The other end of the cable disappears into the magneto under this little rubber boot:

There is a cable adjuster under the boot. Have a close look at the cable ferrule again and make sure the cable is a little slack - if it's not, move the adjuster until it is:

Setting the points gap

The next step is vital - work on the ignition timing with the points gap set up wrongly is a waste of time - the timing settings will be way out. The thing is, when the points are closed, the position of the points heel or pushrod relative to the cam is dictated by the position of the fixed point: if the gap is set too wide (i.e. the fixed point is further away from the moving point) the points heel will contact the cam later than if the points were set too tight - which alters the ignition timing.

Start by removing the points cover from the end of the magneto - swing the spring clip aside, or unscrew the cover.

This reveals the points and the cam. You can see the shiny surface of the cam in these two pictures:

This is where it is useful to have the bike in gear - you can move the rear wheel to move the points. It's quite difficult to access the points from under the dynamo. This 1942 bike has the short 40W E3HM dynamo - access is even worse with the long 60W E3L. You may wish to take the dynamo off while you adjust the points.

Use your toolkit magneto spanner with it's built in 0.012" feeler gauge to test the gap - look for a light dragging fit.

Use the spanner to release the lock nut under the fixed point and adjust the fixed point. Feel free to move the point - on this magneto, it is much easier to access the points with them at the 9 o'clock position, though the points are closed at this position. You must move them back onto the cam (12 o'clock position in this case) to test the gap.

Don't forget to do up the locknut when you are finished - but note that moving the locknut usually moved the fixed point a bit. Test it all again when it's done up tight.

Checking the timing

This is what we came for.

The first step, if you don't have one, is to make a graduated stick. Mine is a Wagamama bamboo chopstick; it's a good idea to drill one end for a loop of wire or string - something to stop the stick disappearing down the plug hole.

Stick it vertically in the plug hole, and move the piston with the back wheel until the piston pushes the stick upward while you hold it vertically in the plug hole. When it is as high as it goes, make a mark on the stick aligned with some convenient geographical feature - a church tower, TV mast or even the top of an adjacent cylinder head fin.

This is 'top dead centre' or TDC, the highest point in the piston's travel. Use a ruler to measure some graduations above your mark - mark 1" in 1/4" increments, with something indelible like a Sharpie marker.

An aside that you might want to consider. There are obviously more accurate methods of measure the piston position and detecting points opening than the method I describe here. This method is simple, but not particularly accurate - it's 1920's technology not 2020 technology, but it will get you going and get you home.

Personally, I get a lot of pleasure from this low-tech approach; I also ride my bikes on roads that existed when they were built and remember, with a manual advance magneto, the lever can be moved at will - there is little point in setting your piston position to the nearest half-millimeter when the lever setting is so inaccurate.

Next, wind the piston backwards and put your thumb over the plug hole. Turn the wheel forwards until you feel the air pressure trying to blow your thumb off - this is the compression stroke, where both valves are closed. Turn the wheel back a little way to bring the piston backwards down the stroke. Watch the points move around the cam, noting roughly where the points are when they open.

The Ariel I am working on uses a magneto which turns clockwise when viewed from the points, and the engine fires at something like 11 o'clock. In this case, I position the points at 9 o'clock, because I can get to them easily and place a blue Rizla cigarette paper between the points. Holding the cigarette paper, turn the engine unto the points release the paper.

Now, if I do this with the ignition lever set to full retard, the paper is released (and the engine would fire) at TDC. If I set it to full advance, the paper would be released with the engine about 5/8" advance, which we can see from the position of the stick:

The various notes Ariel issued for the bike recommend setting the ignition fully advanced at 3/8" - 1/2" BTDC, or 'Before Top Dead Centre'. Since my lever allows the ignition to be set between 5/8" and TDC, this is OK.

Remove the timing chain cover

You did remember to put a drip tray under the bike didn't you? The timing cover encloses the magneto chain and this is lubricated by leakage from the oil pump. consequently, there is always some oil within the cover and you will want to catch it as you remove the cover screws.

Check the chain tension

The timing chain needs to be maintained at a reasonable tension as it wears, or it will be carving your timing chest to pieces. If you look closely at this picture, you can see two grooves in that threaded post where the chain has touched it in the past.

The tension is not too critical, but there are a couple of points to bear in mind. Too loose, and it will be noisy and wear the case; too tight, and your magneto bearings and possibly the armature will suffer. Worse is a misaligned chain - it's quite easy to get the two sprockets out of parallel which is going to wear the chain very quickly.

The workshop manual for the W/NG says 3/8" total movement, which feels about right.

The chain tension is adjusted by moving the magneto backwards and forwards on its mounting platform. An Ariel magneto is retained by these three inaccessible bolts, which pass up through the mounting platform into the magneto. Slacken them by whatever contortionist spannering you are capable of, and pull the magneto backwards until the tension is where you want it. Before you tighten the bolts, make sure the magneto is pushed into the back of the timing case - there is a foam seal there which prevents the oil, splashing around the timing case, from coming out.

Set the timing

If your ignition timing was not to your satisfaction, you will need to loosen the magneto chain sprocket to reset the timing. Back off the nut a few turns, leaning on the rear brake lever as you do so:

Fit your puller to the large thread on the sprocket. You will have to wind the screw fully out to get it on, but once it's fully home you can wind in the screw and the sprocket will come off it's taper.

An alternative approach which you may find easier is to remove the sprocket on the camshaft rather than the sprocket on the magneto - the effect is the same, but the camshaft will not move while you put the sprocket back on, whilst the magneto might.

Set the advance lever to full advance and using your graduated stick, move the engine into the full advance position - 1/2" BTDC on my W/NG. As before, make sure it is on the compression stroke or you will have a mysterious failure to start.

Next, put your fag paper back in the points.

Turn the points by hand in the proper direction. They should move easily - you are turning the magneto armature which is no longer connected to the chain drive from the engine. Turn them until the paper is just released and no more.

Next, go back to the other side of the bike and push the magneto sprocket back onto the taper, and do up the nut. Go back to the 'Checking the Timing' section to make sure you have it set correctly; you don't need to be too fussy as the handlebar lever allows you to adjust the timing to wherever you want it.

Next, reassemble the timing cover; put the plug back in and replace the dynamo if you removed it, and go for a test ride.

Old Bikes & Morris Dancing

This weekend saw the annual Potty Morris Festival here in Sheringham, with 36 teams from all over the country visiting to dance in different traditional styles & costumes. Saturday & Sunday saw the town filled with folk in various regalia with bells ringing on every street & the sounds of the melodeon, fiddle & drum playing to accompany the dancers

The Bourne Borderers, from Lincolnshire

This was the 22nd Sheringham Morris Dance Festival since the event was set up by Clive Rayment & Reg Grimes. For the first time the event was unfortunately without the Sheringham Lobster Potties themselves, but 36 other teams danced Cotswold, Border, North West & Molly traditions over ten dance spots all over the town.

Leicester Morris Men

Holt Ridge Morris at the Crab & Lobster Festival, May 2015

Potty Festival is not complete without Real Ale, and the pubs were filled with revellers & more musical entertainment in the evenings.

Sunday saw us among the motorcycle exhibits at the Vintage Transport Festival. The bikes park up on Sheringham station platform. The loco, a BR Standard 4 number 76084 was outshopped in 1957 so she is contemporary with many of these bikes. Here's a lovely Norton Dominator 88 with my Bantam in the background, a C15 and another Dominator.

Same scene, a bit later in the day. The sun has gone but we have a Rapide and a Commando Roadster.

Very handsome Dominator, hiding my Square Four from view

A Silver Bantam, and the Suzuki AC50 & BSA SS80 Sports Star seen at the recent Classic Car & Bike Show.

A group of scooters:

A Matchless G9 with a very interesting looking Gold Star:

There were a lot of Velocettes this year:

A nice BSA A10:

The silver Bantam again, with Amelia in the background just to prove she was there: