I've bought a brand new Lucas wiring loom for my 1960 A10 but i'm confused by the diagram that came with it.
It says for A10 1954 - 1962 swinging arm frame but the diagram shows negative (-ve) Earth. Isn't the 1960 A10 +ve Earth? What should i do, just wire the black -ve wire to the +ve terminal of the battery and the red +ve wire to the frame? Anyone else bought one of these looms and if so what's what with it?
(https://live.staticflickr.com/65535/52477453325_5e45d64a6d_b.jpg) (https://flic.kr/p/2nXfEA2)WP_20221104_17_42_33_Pro (https://flic.kr/p/2nXfEA2) by XJR1200 TIGER (https://www.flickr.com/photos/156475646@N07/), on Flickr
Just reading the Haynes manual, it says the polarity was reversed in 1951 so the earlier ones had +ve earth and the later ones had -ve earth - or was it the other way around?
Oh yes, the good old Haynes book of Lies.
You are correct that the polarity was reversed in 1951, as it states in the book of Lies and Trickery, but at the start of the Electrical equipment chapter in said book it states Polarity of system 1947 - 50 negative earth and 1951 0nwards positive earth.
Hi,
Even late 12v A65s are still +ve earth.
Dave.
red is normally earth so the wiring harness looks correct and is positive earth.
Quote from: EDDIE SIMPSON on 04 Nov, 2022, 20:24
red is normally earth so the wiring harness looks correct and is positive earth.
But on the picture it says "Earth" with a negative with a black wire.
If you are unhappy withn the harness I suggest send it back to the supplier, or at least ask them about it.
The swinging arm models were certainly positive earth.
Below wiring diagram from the 1960-62 owners manual.
Thanks for the diagram.
You're right, i'll take the loom back on Monday.
its hard to read the diagram but that earth is a misprint. i can see the black[ live ] wire goes to the ammeter, horn, regulator and rear brake switch which is correct. i cant read the headlamp switch wires but one should be live from the ammeter either black or brown.
the other red wire goes to the frame post by the battery usually.
It's not a very complicated wiring harness and, assuming the +ve and -ve battery connections on the Lucas wiring diagram are simply labelled the wrong way around, all you need to do is to check the harness wires and connections against the wiring diagram from the Owners Manual, and check all the harness connections fit to where the components are on the bike.
Apart from possibly the colours of some of the wires, I'm not sure there is much of a difference between the -ve and +ve earth versions of the wiring harness.
Thanks for the encouragement lads, much appreciated. Here's a better picture of the Lucas diagram. Hope it makes a bit more sense visually.
(https://live.staticflickr.com/65535/52478470169_3db296475f_b.jpg) (https://flic.kr/p/2nXkSRP)WP_20221105_08_33_31_Pro (https://flic.kr/p/2nXkSRP) by XJR1200 TIGER (https://www.flickr.com/photos/156475646@N07/), on Flickr
As far as I can see, the colours in the diagram are not completely consistent with the original wiring harnesses for either the positive or negative earth systems. For example, neither had a red/black wire to T2 as far as I can see.
Unless you are after 100% authenticity with the original wiring harness, the actual colours used don't really matter as long as you can work out which wire and connector is which. As far as I can see, the wires in the Lucas diagram appear to correspond to those shown in the wiring diagram from the owners manual and, as long as the wiring harness fits your A10 with the right connectors in the right place, it should do its job properly.
I've used one of these looms and the only fault was the battery terminals + & - had been labelled the wrong way round. I think the confusion started with the Owners manual diagram as posted by Julian. It shows the black wire going to the positive terminal on the battery and going to earth, then a brown wire going to the neg battery terminal.
Perhaps Wassell thought BSA had screwed up with their diagram.
Quote from: Spaceman on 05 Nov, 2022, 10:00
As far as I can see, the colours in the diagram are not completely consistent with the original wiring harnesses for either the positive or negative earth systems. For example, neither had a red/black wire to T2 as far as I can see.
Unless you are after 100% authenticity with the original wiring harness, the actual colours used don't really matter as long as you can work out which wire and connector is which. As far as I can see, the wires in the Lucas diagram appear to correspond to those shown in the wiring diagram from the owners manual and, as long as the wiring harness fits your A10 with the right connectors in the right place, it should do its job properly.
Thanks for the info, and no i'm not going for 100% authenticity.
Quote from: Servodyne on 05 Nov, 2022, 10:45
I've used one of these looms and the only fault was the battery terminals + & - had been labelled the wrong way round. I think the confusion started with the Owners manual diagram as posted by Julian. It shows the black wire going to the positive terminal on the battery and going to earth, then a brown wire going to the neg battery terminal.
Perhaps Wassell thought BSA had screwed up with their diagram.
Thank you too. All good to hear.
now i can see the diagram better i can see some problems with this loom.
its showing the regulator earth to a black wire and the horn earth to a black wire with a brown live. it is all wrong in my opinion.
you can easily modify it for black live and red earth by belling out the live and earth circuits and modifying the loom. however as already suggested take it back and get your money back
The wires mentioned look fine to me comparing diagrams with the only difference being the horn press wire being black rather than black/brown as in the Owner's Manual diagram. In both diagrams, the regulator earth is shown as a black wire.
As said, if you are not worried about having authentic wire colours, it is just a question of making sure the harness fits the bike and has the right connectors in the right places. I'm not sure any of the A10 harnesses being advertised use authentic wire colours!
::) well well, which way to turn. :-\ All good ideas though. I'm leaning towards giving it a go or am i ;)
I have never found the wiring looms match the book colours. I just fit to frame and follow where the wire lay. You soon work out which go where.
i am not so sure fitting this loom is a good idea. studying the diagram further black must be the earth circuit and red then brown the live circuit. however you have black wires going from t5 supplying live to the rear light and speedo bulb. it should be maroon. then there is a spare brown wire going to the rear light ?. brown is live from the ammeter and battery. are the black wires from t5 a separate circuit from the black wire earth circuit?
when you have a breakdown the colour scheme on this loom will throw you into total confusion when the correct scheme is better because bsa used more coloured wiring.
Hi,
Al Osborn, AO Services, will supply a wiring kit complete with correct colours, connectors and self amalgamating tape etc. A dynamo kit is about £36 including postage.
Dave.
The only way you will be able to determine whether this wiring harness is usable or not is by checking it against the OEM wiring diagram - the coloured wiring diagram provided is clearly not 100% accurate! I would be surprised if the harness was not usable!
If you are not able to check the wiring harness in this way then it is probably better to send it back and buy the one recommended with the correct colour coding.
Quote from: DAVE BRADY on 05 Nov, 2022, 21:46
Hi,
Al Osborn, AO Services, will supply a wiring kit complete with correct colours, connectors and self amalgamating tape etc. A dynamo kit is about £36 including postage.
Dave.
On looking at this web site, I think it may not be suitable as they appear to only provide the wiring harness components for the Buyer to construct the loom themselves rather than providing a complete manufactured loom.
I did see the loom being advertised below which looks as though it may have the correct wire colours but you never know until you get your hands on it. On reflection, it may be best to try to use the loom already purchased?
https://www.autosparks.co.uk/bsa-a7-a10-braided-wiring-harness
Hi,
Yes, the AO Services kit is exactly that. I have used on for an A65 and it worked out quite well. As the wires provided are over length it is then possible to route the harness perhaps better and tidier than with a pre made one.
Dave.
Thanks to everyone for advice. Thanks Dave Brady, i took the other loom back to the shop today and got one for a +ve Earth though it states on the diagram that it's for a 1948 - 54 A7/A10, no swinging arm model. Comparing it to the Haynes and the colours correspond very nearly the same. Confused is the word, and i'll keep the other loom as a standby. Trust Lucas indeed.
(https://live.staticflickr.com/65535/52483708189_5dd74775fd_b.jpg) (https://flic.kr/p/2nXNHWv)WP_20221107_12_36_07_Pro (https://flic.kr/p/2nXNHWv) by XJR1200 TIGER (https://www.flickr.com/photos/156475646@N07/), on Flickr
that diagram and loom is a lot better.. what bike was the other loom for?
also i would run a earth wire to rear light unit for reliable rear light and brake light.
Hi Eddie, i'm getting you and Dave mixed up, newby-itis going on.
The other loom is for an A10 from 1954-62 swinging arm model and my bike is an A10 swinging arm model from 1960. Something is amiss at Lucas quality control i think.
Thanks for your help.
Hi Catz,
I don't mind being mixed up with Eddie.
Dave.
Im currently rewiring a 1978 Harley xl1000, the loom is burnt in parts and has had wires joined in over the past so one colour going in may be a different one coming out. you are lucky having options for BSA looms, local dealership cant even supply plugs or a battery for the Harley!!
needless to say, Im doing it myself. Ive got a couple of original looms on ebay but dont think they are A10, my a10 plunger was rewired ourselves.