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holdfast
Joined: 30 Dec 2009 Posts: 5 Location: north east worcestershire.
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Posted: Wed Dec 30, 2009 11:47 am Post subject: AUSTIN 301 LORRY/POLARITY CHANGE |
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Hello
i wish to change the polarity of my 50's lorry. it is positive earth with a dynamo.
i know the starter motor is not polarity sensitive, but i am afeared that something else will short out or explode if i change anything else.
where do i start?
who will hold my hand? |
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Phil - Nottingham
Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham
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Posted: Wed Dec 30, 2009 12:31 pm Post subject: |
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Unless its got a radio and possibly a clock - nothing really.
If it has ammeter then leads will need swapping as will coil.
Dynamo may need polarising if does not charge by touching jump lead a couple of times on the D (small) terminal.
Note also that battery terminals are different sizes so may not fit well after just swapping over leads especially if helmet type so will need renewing _________________ Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2 |
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Jim.Walker
Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield
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Posted: Wed Dec 30, 2009 12:44 pm Post subject: |
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We changed lots of vehicles battery polarities to enable the use of solid state two way radios. There are absolutely no problems except with solid state (transistor) components or motors with permanent magnets for the field magnetism (instead of windings). Wound-field motors, like your starter motor will run in the same direction. It is very unlikely that any motors on a 1950s vehicle will have field magnets or solid state electronics.
The procedure is simple. Fit the battery with the polarity reversed and remove the field (small terminal) wire from the dynamo. Connect a jump wire to the +ve battery terminal and hold it on the dynamo field terminal for 5 to 10 seconds. That will reverse the polarity of the residual magnetism in the field poles and the dynamo will charge with positive live.
Job done! But if your regulator makes buzzing noises you did not hold the jump wire on long enough.
There is one exception I know of which is the Daimler DR450 range. There may be others. But if so they will have an alternator WITH POSITIVE EARTH. As long as you have a dynamo there are no problems.
While I was typing this Phil from Nottingham beat me to the posting. He rightly mentions the ignition coil connections. I over looked that, but the small dynamo terminal is the "F". _________________ Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then!
Last edited by Jim.Walker on Wed Dec 30, 2009 2:04 pm; edited 1 time in total |
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holdfast
Joined: 30 Dec 2009 Posts: 5 Location: north east worcestershire.
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Posted: Wed Dec 30, 2009 12:57 pm Post subject: AUSTIN 301 |
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Many thanks for advice, i have wanted to fit a radio for years as 30 mph journeys are a bit tedious!
if you hear a BANG over Bromsgrove i havent been paying attention! |
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First Bedford
Joined: 11 Dec 2009 Posts: 107 Location: Darlington, Durham
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Posted: Wed Dec 30, 2009 8:31 pm Post subject: |
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I have a 52 Bedford, same positive earth. Is there a benefit to changing Polarity?
Pete |
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Jim.Walker
Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield
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Posted: Wed Dec 30, 2009 11:08 pm Post subject: |
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I would say "no", First Bedford, unless you wish to add modern electronics such as things with transistors or diodes etc.
Just my opinion. I have 3 +ve earth machines and I see no point in changing them from original (authenticity?). _________________ Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then! |
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Phil - Nottingham
Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham
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Posted: Wed Dec 30, 2009 11:09 pm Post subject: |
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The only benefit is that modern electronic equipment can be used without having to make arrangments to ensure it casing polarity is negative earth togther with anything connected to it eg radio aerials. _________________ Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2 |
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First Bedford
Joined: 11 Dec 2009 Posts: 107 Location: Darlington, Durham
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Posted: Thu Dec 31, 2009 12:46 am Post subject: |
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Sorted, it will stay as original.
Pete |
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