Wiring from scratch

[Ian Williams]

I am another one who regularly say's that I consider the original 6V system adequate. May arguments are presented as to why one should modernise, and a few of them even have some plausibility to the reasoning. However I have, since I first started playing with sevens in the early 80's, NEVER had ANY problems running with 6V, period!

[Ian Williams]

For the benefit of those reading this who may be new to the Austin 7 world don't believe all you read, 90% of the 12v conversions are done on an owners whim rather than any real need.

[RupertW]

Since originally asking the question I've finally got round to making some progress on the electrics, and I've ended up sticking with a broadly original 6V setup which I have successfully tested to ensure it all works as it should when test wired so on to doing it all properly and neatly now. I did wince slightly when I saw how much the cost of 6V batteries have gone up lately which was part of the reasoning behind originally wondering about 12v. When I enquired about the price increase I was told it's largely down to shipping as apparently the 6V batteries need to be shipped differently as they're more prone to leaking in transit.

I think originally it would have been earthed only to the body, but is it worth also running an earth to the gearbox? Presumably i'd still need an earth to the body for lights etc. unless I run an earth back from them?

In terms of the wire itself, I know it's particularly important with 6V to make sure it's a heavy enough gauge. Aside from cost is there any disadvantage to running heavier wire throughout the car?

Final question - would any of the chummy models have been fitted with dipping headlights?

Any thoughts much appreciated as always

[David Cochrane]

In answer to your first question, yes it is definitely well worth running a heavy tinned-copper braid from the battery earth to a bell housing stud. The chassis has a convenient lip in which you can sit this braid. You should also run an earth wire back from each headlamp and the rear lights to a common earth point, e.g. a brass P-clip soldered to the oil pressure gauge/button pipe behind the dashboard.

I can't think of any disadvantage in running heavier wire through the car.

[Robert Leigh]

Good earthing is particularly important for the starter. At 6v the starter will draw twice the current drawn by a 12v motor for any given power requirement. I have never been aware of heavier wiring for 6v motors than for 12v, but the voltage drop at a given load will be be twice as much for a motor at 6v as it is at 12v. In my experience the majority of slow starter motor problems (giving poor starting) are caused by poor connections such as screws holding the cable into the battery clip. Soldered connections are far superior. Far less frequently the problem is in the motor, and it will need less attention if it is enabled to spin as fast as possible by having good connections so that the engine starts more easily, meaning a shorter period of having the motor on full load. Sorry to labour the point but it is well worth attending to such things.

[Parazine]

Final question - would any of the chummy models have been fitted with dipping headlights?

No, dipping headlights were first used from September 1931, the initial system was the Lucas-Graves double filament bulbs but later, Lucas Dip and Switch headlamps became standard. All previous headlights were single, fixed filament.

[Steve kay]

Two electrical contributions. The first for what it’s worth is agreeing with the Stick to 6 Volt school of thought. Reasonably cared for, this is wholly adequate.

The second contribution is electrical bad news. The Ribblesdale chaps in Preston seem to have lost their magneto man, and are most apologetic that they can no longer do any magneto repairs or rewinding. They have been reliable and utterly honest about delivery time, so now who do forumists recommend?

[David.H]

I think the AG might have had the Lucas Graves system...but it was 19 32 although short chassis, steel body & Chummy style ...is it regarded as a Chummy? 
Answers on a postcard please......

[RupertW]

Many thanks all for the pointers.

Next question then, is on an SM5 switch panel, if you select 'S' which I'm assuming means sidelights, then presumably it'll light up the tail lights, but which bulbs would it light up on the front? The headlights I have (which may not be correct but I'd still ideally like to use) only have provision for one bulb in the reflector. My later Box Saloon has a small separate bulb in the reflector for the sidelights which makes sense to me, but I can't then see how it would work with these earlier headlights unless there's an entirely separate set of sidelights, which I don't think they would have had originally? Could I use a dual filament bulb here?

[Howard Wright]

Hi Rupert

Chummy and early saloons did use a dual filament bulb, at least that is what is on my RK and Chummy lights on my special.

Cheers

Howard