The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: JHG1958 on 06.07. 2020 18:41

Title: new wiring loom
Post by: JHG1958 on 06.07. 2020 18:41
I am not happy to use the standard wiring loom for my Golden Flash.  The main reasons for this are:
So I have a plan and produced a wiring diagram attached.  I would appreciate comments from you guys


I hope by putting power to the wireless relay from the lighting switch, if the relay fails, the bike will stop but the lights will stay on (sounds a good idea to me).
I hope by using a wireless relay positioned under the seat will make it difficult for people to Hotwire the bike.

So, moving the lighting switch to position 2 energises the relay and the pilot light, horn, tail light and brake light.
The remote control can then be used to energise the ignition and the engine can be started.
I will be able to run the bike without the headlamp on if I need to charge up the battery.

The third position on the lighting switch energise the headlamp.
The engine can be stopped by turning the light switch to position 1 or pressing the remote.

Rude comments on a postcard

John
Title: Re: new wiring loom
Post by: JHG1958 on 06.07. 2020 18:43
Pants picture try this pdf
Title: Re: new wiring loom
Post by: Greybeard on 06.07. 2020 18:49
Pants picture try this pdf
It looks like the remote relay is energised all the time.
Title: Re: new wiring loom
Post by: Greybeard on 06.07. 2020 18:55
The loom I bought for my bike has a return, (earth) wire.
Title: Re: new wiring loom
Post by: JHG1958 on 06.07. 2020 19:49
Pants picture try this pdf
It looks like the remote relay is energised all the time.


No. The red line to E is the switched line coming out at A.  Energising the relay is D (blue) with common earth F.

I heard the new looms had a earth wire. Sounds a good idea.
Title: Re: new wiring loom
Post by: Black Sheep on 06.07. 2020 22:33
A 12v regulator and a 6v dynamo ain't a good combination in my experience. You can end up with commutator segments flying off (half way over the Forth Bridge at night with a long way to go in one instance). Go the whole hog and get the dynamo upgraded while you are at it.
Title: Re: new wiring loom
Post by: RichardL on 06.07. 2020 23:50
As one who relies on the magneto and little else to assure I get home regardless of battery condition, this looks like three (or so) points of failure that were not present when the bike left Small Heath.

Richard L.
Title: Re: new wiring loom
Post by: chaterlea25 on 07.07. 2020 00:32
Hi JHG,
In normal circumstances the horn and brake light are not wired through the ammeter

I have a custom loom and switch gear on my SR including a multi fuse block but rely on magneto ignition (original BTH not the modern thing)

John
Title: Re: new wiring loom
Post by: groily on 07.07. 2020 06:42
Dont quite get the Dyn & Reg wiring. Think you need to look at lettering again? Dyn F to reg F, power off A for ammeter etc and E to earth. Could be I'm cross eyed from looking at sruff on a phone cos I'm away on holiday, but it doesnt look very right from this corner of Sicily!
Not had  probs with the 12v / '6v' mix myself but I know there are schools of thought. The only dyn that I threw the comm on was a fine-wound '12v' job!
Title: Re: new wiring loom
Post by: Rex on 07.07. 2020 08:39
A 12v regulator and a 6v dynamo ain't a good combination in my experience. You can end up with commutator segments flying off (half way over the Forth Bridge at night with a long way to go in one instance). Go the whole hog and get the dynamo upgraded while you are at it.

I've long agreed with this principle too. A nominally 6V dynamo runs really hot when regulated at 12V, and even though many say they've done it and it works fine I wouldn't trust it either to last or to work effectively.
I rebuilt the dynamo with a 12V armature and field coil and it provides more than enough output to run the lights etc reliably.
Title: Re: new wiring loom
Post by: BSA_54A10 on 07.07. 2020 08:52
Better security ?
really ?
The days of opertunistic thieves roaming the countryside looking for magneto powered bikes to pinch by riding away on them ended around 1980
If a thief wants your bike they will take it
Hiding a tracking device might mean you will be able to find out where they put it or follow the truck containing it.
A pocket pager will posssibly alert you to the fact your bike is being stolen just soon enough to watch the truck driving away with it or a bit earlier so you can get punched in the face before they drive away with it.
So all you doo-dad will do is fall apart when you are 100 miles from help and in a phone dead spot so by the time you get help your bike will be gone .,
Title: Re: new wiring loom
Post by: beezermacc on 07.07. 2020 09:31
There have been all sorts of arguments on this forum which stem from people making modifications to their bikes. Some people fall into the 'Keep it original' category, others say 'make as many improvements as you can' and some fall somewhere in between. My opinion is that you should have a fairly clear view of how you expect to use the bike and build it accordingly. A think 12v is a good idea but I would do a proper conversion, i.e. 12v armature, field coil, and regulator. I can't see the point of any of the other modifications you are making, or the benefits don't warrant the effort. Don't forget that the more you modify your bike the less of a 'classic' bike it is. The A10 was a good bike and, if put together properly, will serve your needs perfectly well in its original form. I find the new 'Lucas' looms supplied by Wassell to be of very good quality, not perfect, but very good.
Title: Re: new wiring loom
Post by: JHG1958 on 07.07. 2020 11:04
I can appreciate the keeping it original school of thought. I have kept the engine and gearbox as a Golden Flash, no fancy cams or pistons. In any case I would like to keep the Golden Flash looking like a Golden Flash since that as the reason I bought the bike. So chrome tank painted valence mudgards, etc. A bit of a dilemma about using a twin leading shoe front brake. This question can wait.  Perhaps a new thread about keeping it original vrs modifications.

The main reason for putting in a wireless relay is so I do not have an ignition switch. I think it will improve security in a very unobtrusive way, but it is true if they want the bike they will take it.  At the end of the day a bloody big chain around a lamp post is probably best.  I must admit I have not heard of a lot of classic bike thefts.  I had not thought about a tracking device. I will look into that.

The 12v conversion seems sensible. I had planned to use my dynamo plus a belt drive as recommended by SRM. This feedback is making me think about a rewind or even an alternator as I have no regulator yet especially as I ride with my headlamp on.

I did read all the arguments about the Mag vrs electronic ignition. My mag is in a bad way so I have bought a Lucas electronic kit.  With my old A10 several decades ago, I cooked my mag to drive away the water and it worked fine after that.  Do people still do that?

I would rather make my own loom. I find the electrics fun especially on something as simple as this.  I did note that the horn and the stop lamp were not on the ammeter. I cannot see why not. Trying to get a horn button that does not go to earth may be impossible but I will try.

As for the letters on the regulator. I may have them wrong I took them off a Haynes manual.  Basically it is 2 wires to the dynamo then positive and negative output.  The headlamp switch is a bit of black hole.  I will have to buy one and see.
Title: Re: new wiring loom
Post by: Greybeard on 07.07. 2020 11:17
The horn button: Mine does earth to the handlebar but the steering assembly is earthed inside the headlamp cowl and then returns via the loom. The horn itself has a return wire in the loom.

My security measures: I have a hidden mag kill switch. If I must leave the bike unattended I have a f-off heavy duty chain to lock the bike to a tree or lamp post etc.
Title: Re: new wiring loom
Post by: Seabee on 07.07. 2020 12:53
I use my fork lock as a short stop anti-theft device. Big chain and lock otherwise...…………..
Title: Re: new wiring loom
Post by: Swarfcut on 07.07. 2020 13:34
How you proceed depends on what's best for you.  As an observation, an existing commercially available loom will cope with 12 volts. The current flowing remains more or less the same whether the system is 6 or 12 volts. The higher power required by higher wattage bulbs is compensated for by the higher operating voltage, and 12 volts gives a little more choice in the way of bulbs, horns and electrical accessories.

   The relative cost differential of 6 volt and 12 volt armatures and field coils is marginal, and if the existing dynamo is truly finished, then well worth swapping for the higher output parts.

 The usual practice of wiring brake and horn directly prevents the ammeter being subjected to irregular high currents, more as a way of preserving its longevity, and also  if wired through the ammeter a failure would render these "safety critical" components inoperative.

 The Lucas regulator terminal block always raise a smile..... depending on model the letters are D.E.A.F or F.A.D.E     Says all you need to know about Lucas Electrics......

 If making your own loom, add a nice big earth wire from Forks to frame/battery earth. Normal earth return from the headlamp and forks is through the nicely greased headstock bearings, and adding an extra earth often improves an otherwise weak headlight output. Never been a fan of magneto cooking, preferring airing cupboard or top of the wardrobe storage

 Swarfy.

 
Title: Re: new wiring loom
Post by: Rex on 07.07. 2020 16:18
Regarding earth paths, there's a good earth connection from the handlebars to earth via the clutch cable, and depending on the design, possibly the throttle cable, choke or even decompressor too.
A separate earth cable run to the rear light is also sensible.
Title: Re: new wiring loom
Post by: Swarfcut on 07.07. 2020 18:20
Rex   Yes, greased cables do conduct.   Years ago, swapped the engine unit on an original Mini.  All was good, started, ran fine, but the choke knob was stuck.   Realised in our haste to finish, muggins had forgoton to re attach the chassis/engine earth strap and the starter current had found its way home down the choke cable and welded the inner and outers together. These days I always add an extra direct earth from the battery to the block on old time classics, to give the starter circuit a better chance.

 Swarfy
Title: Re: new wiring loom
Post by: BSA_54A10 on 08.07. 2020 06:41
Rex   Yes, greased cables do conduct.   Years ago, swapped the engine unit on an original Mini.  All was good, started, ran fine, but the choke knob was stuck.   Realised in our haste to finish, muggins had forgoton to re attach the chassis/engine earth strap and the starter current had found its way home down the choke cable and welded the inner and outers together. These days I always add an extra direct earth from the battery to the block on old time classics, to give the starter circuit a better chance.

 Swarfy

Just ask any one who has a 71 on model with that idiot front brake switch.
Yes greased cables, connected to rubber mounted handlebars and a brake plate that is grounded through a greasy steering bearing.
They conduct really well.
Title: Re: new wiring loom
Post by: Rex on 08.07. 2020 10:03
"Greased" has no bearing on the issue. The path would be, handlebar, lever clamp, lever, cable nipple top end, cable, lower end cable nipple, clutch mechanism etc.
The '71 on OIFs had rubber-mounted 'bars and no hard-wired earth connections to the Dan Dare switchgear that I can recall, yet the horn worked just fine.