1952 Inter wiring questions

They list 2 harnesses dependent on where the horn lives, N3 or N4.

The striped colours came in in 1963. I very much doubt that any bike was wired ALL BLACK as that aids confusion. What ever the colours were the chances are that you won't get the right colours neither, In the 50s there were often two shades of RED and maybe two shades of blue. I suggest you use post 1963 colours following the British Vehicle colour scheme. Each striped or plain wire has a specified job, following the scheme means that you don't need a wiring diagram. If you did find an alleged loom for the Standard bike, so many time I have seen awkward things to sort out, which by the time you have sorted you could have followed the Standard post 1963 colours and understood the wiring as you do it. See aoservices.co.uk for a post 1963 colours kit of wires.

Positive earth, the wiring is the standard setup for most Magdyno equiped bikes from the 50’s

john

... as Nigel says negative earth for 1952. I must admit positive earth always confuses my small brain.....

Submitted by John Doig on Thu, 11/01/2024

Positive earth, the wiring…

Positive earth, the wiring is the standard setup for most Magdyno equiped bikes from the 50’s

john

You have attached a picture of a negative earth wiring diagram.

My 49 Inter has rubber insulation with cotton covering and coloured collars or ferrules.  Negative earth and magdyno. Replacement is on the cards as the rubber is a bit crumbly.  If you are keen on originallity would look for a local loom maker who supplies the aero industry, they still use cotton rayon serving.

Jon

My prewar 16H from 1937 is negative earth and has mostly original coloured cotton coated wires.  I think I read that end sleeves were used by WD during the War, which makes perfect sense in times of shortage.  The history of positive and negative earth seems confused.  Positive earth seems to have become more general in the early 50's.

Prewar and even up to the 50s dynamo (magnetos) machines tended to be Negative earth. In the 50s BSA ,Nortons (AMC) and a lot of the smaller bike companies went over to Positive earth. Now we ask the reasons for/against the change. I can't find the reason for the change to Positive earth except that the alternator system came out (cars and bikes) about then. Certainly positive earth can cause electrolytic corrosion in cars and was eventually changed in favour of Negative earth.In the magneto (ignition) bikes. The polarity of earth is NOT relevant or of any concern.The Dynamo can be polarised either way round and provided the dynamo and the battery are connected the same way then all is well. Traditional incandescent light bulbs don't care either. The problem only becomes an issue in this modern day when ELECTRONICS appear on our machines, ie LED lights are such, electronic dynamo regulators are such. Now we MUST keep the polarity in line with the electronic part we fit, or we get expensive smoke.

Positive earth was standardised in an auto industry agreement, post-War.  It was not universally followed though.

In 1960s UK, a return to negative earth appeared earlier on GM (Vauxhall) products than BMC (Austin/Morris).  The change appeared to coincide with the appearance of the alternator on BMC cars.

Both positive earth and negative earth were touted as somehow mitigating corrosion.  The evidence of our eyes said it was irrelevant.

The evidence of our eyes said it was irrelevant. NOT so. If you leave a battery connected to a car or bike for any time ie a year or so then you will see more corrosion on the Pos. terminal than the Neg. This is due to electrolytic corrosion. Of course if you remove the battery every few months or even after 6 months and clean the terminals and connectors you will be removing such corrosion. One of the early events was for copper radiators on Pos earth cars to 'spring a leak' due to the electro galvanic action on the copper. Our new plastic radiators do not suffer from this of course. Nor the Neg. earth vehicle.