Unloading your dynamo - and updating your lights

A year ago I replaced most of my bulbs with LEDs, if you remember my 'Dusky Jaunt' around Norfolk. I changed all the lamps, except the headlamp to LEDs; the headlamp became a 35W/35W halogen.

Since then I have become aware of LED headlamps in BPF packages. I got this one from Classic Dynamo & Regulator Conversions.

Now, as the electrical engineers among you will realise that the 35W headlamp is about half the output from my C35SD dynamo, which gives something like 70W at full output and balances charge at 40 mph with the headlamp on. The SQ4 currently runs a 6V halogen, which looks like this on the road:

Low Beam

 You'll note the white LED in the speedo! Here's the halogen again:

High Beam

Now, 35W at 6 V is about 6 A. This little chap passes 0.52 A on low beam and 1.04 A on high beam (which actually leaves both LEDs on, doubling the current and the light output) and you get:

A crisp, white light with an excellent beam pattern that will change your night time driving experience.

The result is that the ammeter hardly moves with the headlights on, and I should be able to drive around all day with the lights on.

As you can see in the picture, it is a nice robust construction and there are no filaments to blow and no fragile glass envelopes. In addition, each bulb will work on both 6v and 12v systems (one bulb suits both voltages), so if I convert to 12V at any time I don't need to change this bulb.

You can get negative and positive earth versions of these bulbs. This is how it looks on the road:

Low Beam

 Looking at the high beam picture, you will see that the bulb is arranged to light both the low beam LED and the high beam LED when switched to high beam:

High Beam

The second modification I am going to make is to replace the twin festoon lamps in the W/NGs Italianesque rear lamp with the LED lightboard I bought at the same time.

Bulbs again

A few days later, we have a package from Paul Goff:

All now fitted.

Dusky Jaunt

Well, a little jaunt around North Norfolk yesterday evening left me thinking about my lights, as the nights are drawing ever inward.

The Lucas C35SD dynamo, in standard condition and running 6V into a modern V-Reg regulator rectifier charges the batteries at anything over idling. However, put the main beam on and you have to get to about 40 mph to get it to balance, and this is only running a 35W/35W BPF headlamp as it would have been in 1951, with a 5/21W stop tail - all old-fashioned tungsten bulbs.

In addition to this it has the 3W BA9 pilot light and the 2.4W BA9 light in the speedo.

I think some upgrades are in order. Here's my list:

• 35W/35W QH BPF headlamp - B635BPFQH is the one I have in mind, from Paul Goff
• LED tail lamp - I'll use the LD6RST 
• LED pilot lamp - Paul's LDBA9DWneg is the one here, drawing 1.5W, or LDT10DWH6V depending on which is brighter
• LED speedo lamp - again LDBA9DWneg is the one

as a minimum. And then maybe, because this is getting expensive, I will add:

• LED indicators
• LED indicator relay

I'm toying with the idea of replacing the cheapo repro Lucas 529 rear light, which I fitted as it is much larger and more visible than the original Lucas 480, with a better one from Paul Goff.

I have to make sure that the bike is (if I recall correctly) wired negative earth (which it is - I went and looked at the battery) - the regulator certainly is - because LEDs are polarity sensitive. I'll maybe look into the bright daytime running lights Paul sells as well, since I have two positions for pilot lights.

I also discovered, by the way, that you can ground the side stand on cornering!

Oops

Well, I got out on my test drive, and it feels much happier - smoother, more torque at the bottom end...

Unfortunately, about 5 miles in, a misfire appeared and the engine stopped. Having experienced this many times during the fuel filter saga, I was quick to look for fuel supply problems and cracked the fuel supply banjo to find all was well. The bike started again, only to stop again after about 100 yards - this happened once more, and then I was close enough to push it home...

Charging had looked good on the ammeter from the first day. All the lights worked perfectly, apart from one indicator which persistently rotated around to face the floor, but in general everything had been fine. However today, when I had the bike running again, switching on the lights would kill the engine.

The Lucas C35SD gives 70 W at about 1700 rpm which equates to 32 mph in top gear, but when you are running around town the ignition, brake light and frequently used indicator loads soon drain the battery, which appears as a fuel-starvation-like misfire. I cursed that fuel line again until I realised what was going on, and a CTEK battery charger came to my rescue. Actually you need about 20 W for the ignition alone, or about 3 Amps; in top gear, you get 3 Amps from the generator at an average of 23 mph – these bikes are really not for town use.

My 1951 Mk1 has a 20 Ah battery bank hidden in the Lucas GU11E style fibreglass box. I'd be surprised if you could even get to the shops with the earlier small battery...

Dynamo & Split Bullets

Time to hook up the dynamo. The split bullets so beloved of Mr Lucas are a crude but effective design. I thought I'd show you how to use them. These came from Feked, though you can get them all over the place.

Strip the cable insulation so that there is a similar length of bare wire as the length of the bullet:

Push the wire into the wider end of the bullet, and fan the wire evenly over the bullet:

You may need to pass one of the wires through the Tufnol retaining piece before you fit the bullet. Push both the bullets into their socket in the dynamo and screw the retaining piece in place firmly. You will see the bullets slide into their slots:

Then you are done. Fit the dynamo end cover, making sure you don't trap the flexible brush wires in it, and screw the cap down:

Updating the MCR2 Voltage Regulator

As I've probably mentioned before, I'm a stickler for originality, at least visually. If there is a period component that will do the job, then that is the one that gets fitted. However, I'm not afraid to modify components to make them more effective.

A case in point is the voltage regulator...

The voltage regulator I have with the machine - or the box of bits - is a 1962 Lucas MCR2 - obviously a replacement for the original regulator. While this is perfectly serviceable, it is not suitable for the sealed batteries I have fitted in the Draganfly battery box, so I am going to fit a modern V-Reg dynamo regulator which is designed to replace the mechanical regulator with modern reliable semiconductors, and can handle up to 100W at 6V and even more for the 12V version, provided the dynamo is capable of delivering this power. This device is proven and reliable and is available in Positive or Negative earth, also to run a 6V system. 

New features include: Current limit to the field winding, allows excellent performance when using a 6V dynamo on a 12V system while not straining the dynamo. Tougher electronics, with the introduction of higher energy spark suppression to reduce spikes generated by the dynamo. Improved "thermal foldback" which progressively reduces output power if the regulator gets too hot, indirectly limiting the dynamo from excessive current. Better servo loop stability, with new electronics which 'predict' when the output voltage is nearly correct and control the field current earlier.

The V-Reg 2a will run a 6V system or by cutting a simple wire link will run a 12V system.

Mine came from Paul Goff.

Taking these apart is quite straightforward. You'll need a soldering iron, a screwdriver and a spanner or two. Remove those two nuts and the screw visible in the picture, which may be sealed in with wax:

Then you can take your soldering iron, and a solder sucker, and de-solder the various joints topside. The E and A terminals need the wires de-soldering and removing; the F terminal is more easily disconnected at the frame (the top joint in the picture) and at the back (which you usefully can't see). The D terminal can be de-soldered at the copper cup around the screw from the previous picture:

You can now remove the back plate and the armatures, and you will be left with the mounting base and the four terminals. The F terminal is staying put for the moment, since I will have to cut it off (and after that there is no going back):

The V-Reg has a convenient pair of T-slots in the heat sink which are spaced so that the mounting bolts fit the hole spacing in the old base. The old 'D' terminal is also still in place:

Its then a simple matter of connecting the wires to the terminals:

We will tidy up that wiring when we have tested it!

Dynamo - recharged

Well here we are again, Christmas break and a bit more time. We've had Amelia for two years now, not long by Square Four restoration standards. Various diversions have come & gone, some are still here. I've had three months off work (diverted by a house renovation and a long hot summer, plus a daughter off to university), come back to a major project for Statoil, and I've been asked to write a book. A bike book!

But back to Amelia. Various thing are in the wings - we are working on the engine (long wait for piston rings; still not out of the woods)  sorting out the coil mounting, and finishing the dynamo. The dynamo is key because I understand that you cannot fit the end cover with the primary cases in place, and of course you need the dynamo to set up the valve timing, so I want to have it available before I finish the top end.

So, we had an old post on the dynamo, where we discovered it was intact electrically, but the bearings were shot and it was full of oil due to the failure of the oil seal. So the first job, which I did a few weeks ago, was to obtain the parts from Draganfly. After that, it was time to clear the bench and pull it apart again.

The bearing has to come out first:

Very easy with the heat gun and a large socket, though you have to bear on the inner race which is not ideal, but these are not a tight fit.

This is the drive end in pieces, with a replacement nut, oil seal and bearings from Draganfly. Those parts, looking like a shim and a gasket (because they are a shim and a gasket) are not original. They are (quite proficiently) home made and do not appear in the Lucas workshop instructions for the C35SD.

The bearing shoulder is very thin, and through in one place. So much for Lucas QC. Next stop, the commutator end - and as before the armature is a tight fit in the bearing. Lucas usefully provided a tapped hole, where you can use one of the long screws to push the armature out of the bearing:

So, commutator end in pieces. A proper clean ensues with white spirit to remove all the grease, plus wire brushes and wire wool to reveal a lovely plated surface on the body. Actually, there is no means of removing the commutator end bearing unless you have an expanding bearing extractor (which I don't), but luckily enough, with a bit of heat and some sharp taps on the vice, the old bearing dropped out.

New bearing in place:

Then, on to reassembly. Drive end in place with new bearing and seal:

Clean commutator (those deep scores won't do any harm) with its spring and thrust bearing. This is an early CS35D - later ones used on Mk2 SQ4s have a different arrangement here:

New brushes dropped in and springs hooked back over them:

Field coil reconnected to the terminal post:

And the end cap refitted with some grommets (plus a new O ring around the body, visible in the picture during brush fitting), new screws & fibre washers. By the way, this end cap is the original and was always black:

And here is the drive end:

Job done. I'll have to motor test it before it goes on, but I have a 1986 Ibanez PF400 to fix for my friend Simon.

Batteries

As I've mentioned before, I have a very nice GRP battery box from Draganfly, made to look like a Lucas GU11E battery. Here it is:

Now, the original GU11E apparently has a 20 Ah capacity, which is the peculiar way in which our industry has chosen to illustrate the energy capacity of a battery - it means it is capable of delivering a current of 20 Amps for an hour, or 40 Amps for half an hour, or 10 amps for 2 hours - you get the idea.

Now an Ampere, or Amp for short, is a unit of current, and current is the rate of flow of electrical charge - measured in coulombs. So an Amp is a way of describing coulombs per unit of time - 1 amp represents 1 coulomb per second of flowing charge. So, if you multiply Amps by time (As in Amp x hour = Ah) , you get back to charge again - and units of charge are what is stored in our batteries.

So, in order to get my bike to run for a reasonable period of time without being charged (for when I choose to ride at 10 mph in a traffic queue on the M25 (when did you last see a Square Four do that?)) I need a battery of sufficient capacity to deliver sufficient current for the time I am riding so slowly that the battery is not charging, without running flat and bring the bike to an undignified halt.

You see, according to this chart I draw from the data in the C35SD dynamo instructions combined with some details of the Square Four's performance (and assuming the C35SD runs at engine speed, which it does, more or less) the dynamo does not start charging until you are moving at about 20 mph. So, go slower than this and the battery is draining.

But how much current do I use? Let's work it out:

• my headlamp will use up to 55W, which at 6V needs just under 10 Amps to deliver the power (Power, W = Potential Difference V x Current A)
• my tail lamp will use 5W, which needs another Amp
• Lets assume the ignition coil will need 20 W, or about 3 Amps

Which gives us around 15 Amps, allowing for infrequent use of the stop light and horn. A 20 Ah battery will be flat in 1.334 hours, or 1 hour and 20 minutes. Reasonable? Lets hope so.

So we know what we are aiming at - a 6 Volt battery with capacity of around 20 Ah that will fit in my neat little fibre glass box. Since a year or so into having the Bantam, Beattie has been using a sealed lead-acid battery - the electrolyte is treated to form a gel, so it can't flow out, and the chemistry is altered somehow (I'm not that clever) so that when the battery is charged and would normally produce free oxygen & hydrogen, the gases recombine as water, replacing the lost liquid in the cell. This is really neat for a motorcycle, because it means you can fit them wherever you want (they are really small), they don't drop nasty acid all over your bike (how many rusty battery carriers have you seen?) and because they are made for things like burglar alarms, they are really cheap.

The downside is you cannot abuse them as you can a traditional wet battery - if you overcharge them and lose the electrolyte, you can't replace it.

The thing is, I came to use one of these things the first time because I realised the rudimentary (putting it kindly) charge control system on the Bantam was boiling the original wet battery - so I added a modern solid state regulator/rectifier (from the marvellous Rex Caunt Racing) and was able to use a gel battery. The one on the Bantam is tiny - about 3.4 Ah I think, at 12 V, and has coped perfectly for several years. It even remains charged through the winter, something the old wet battery could never do.

Oily Dynamo

We need to get moving on the engine and we don't have the parts to finish the refurbishment of the dynamo, so we will put them on the list for Drags & move on. Before we reassemble though it makes sense to check everything out.

So, the service manual tells us that the field coil resistance, across both field coils, is in the range 2.6 - 2.8 Ohms:
 

So we set the meter to the 200 Ohm range and short the test cables together, to reveal a resistance in the measuring equipment of 1.3 Ohms.

Now let's connect the field coils into the circuit. This reveals a total resistance of 4.0 Ohms, giving a value of 2.7 Ohms for the field coils alone. Spot on, correct to specification!

Next test - field coils to earth. Should be open circuit, hopefully...

Hey presto, no reading on the meter. Field coils good! Next job, clean the armature & the commutator. Easily done with some solvent, mildly abrasive paper and a razor saw. We'll not attempt to test this since the brushes are in very poor shape and as we said, we don't have the parts to rebuild this beast yet. Continuity tests & earth resistance tests look good though.

 

Here is a view of the brush assembly about to go back in. Clean enough for now, but not clean enough to use. We will finish that when we have some new oil seals & an idea of how this unit left the factory. Black gloss paint maybe? There is no evidence of any paint except for on the end cap:

And here is the drive end. I've re-tapped the hole for the distributor retaining bolt. Fortunately, whoever tried to put a BSF screw in there didn't try very hard and the thread recut nicely. Spare 1/4" BSW screw inserted for now, to be replaced with a stainless one when I can find one. Also, an appropriately sized (but incorrect thread) nut serves to retain the sprocket. Losing it is not an option!

Lastly, tired & oily brushes. Very worn, mangled insulating sleeves, fit for patterns only.

Dismantle, degrease, polish...

Well, I've set about polishing the timing cover, but no pictures! I've decided that I need to find some abrasive wheels to tackle the timing cover since, as you can see from the pictures it is quite discoloured & needs more grief than I can give it with a sisal mop!

So, I have moved on to the removal and resurrection of the Lucas C35SD dynamo. No problem getting it off, but I had noticed a while back that the commutator was full of fluff, leaves and oil. I had assumed that this was down to the fact that the end cover was in a bag with a lot of other parts, and not on the dynamo!

I'd bought a puller as part of the toolkit crusade, and so removing the sprocket was no problem. As we noticed a day or two ago, the nut was missing and the puller screws right on. You undo the nut you can see behind the puller, extract the sprocket, and the dynamo is then held only by the clamp.

So here it is, some hours later after dismantling & scrubbing with a small brush & white spirit. All the major parts are in good shape, with the exception of the oil seal which is completely cratered - it is now obvious why the thing is full of oil. The distributor retaining screw is noticeably bent, and is 1/4" BSF - not what I would have expected in a soft ally casting.

Here's a close up of some of the smaller parts. No wear or other nasties apparent.

 



Next job, when everything is finally clean enough, is to check out the field coils, the armature, and the bearings. The data is all contained in the handy instruction manual, so no problems there. We can then reassemble and do a motoring test before refinishing.

Next though, after a few days real work, we will probably get the abrasives out and finish the timing cover.

A few more electrical items

Well, not much to add this weekend. We've been very busy with work, paintwork for an MZ TS125 and a poorly VW Beetle with inlet manifold leakages. 

All we've managed to do is strip and repaint the dynamo end cap and the regulator. We used Hammerite Kurust on some parts of the regulator, at double strength, which seems to work very well. The parts are painted with high street acrylic aerosols & U-Pol etch primer. The end cap is from the original Lucas CF35D dynamo, the rest of which is still attached to the engine. The regulator is a 1962 Lucas MCR2, with a brass case which though a later replacement part is correct for the machine