Changing to negative earth

[Alan1]

Does anybody have specific instructions on how to change polarity to negative earth please?

[Nick Jones]

Google is your friend......

this is one of many hits I got

http://www.classiccarprojectsh.....e-to-negative-earth/

Only thing I would add is that the +ve and -ve battery posts are slightly different sizes so your clamps may not fit all that well afterwards.  Depending on the type fitted it may be possible to swap them on the cables, fettle them to fit properly or you may need to replace them.

Nick

[Gt6s]

Read that link WHAT A LOAD OF COCK ! It is about ten years since I have done one but the reality is you really only need to change the battery terminals and flash the dynamo or even better BIN the dynamo and fit an alternator. OHH YES ! Bin or Ebay any positive earth radio.

Laurence

[heraldcoupe]

In addtion to what's mentioned in the link, you will need to reverse the connections to your heater blower, the motor is polarised and will spin backwards. It will still move air in the right direction, but the vanes on the blower drum are shaped so they're more efficient in the intended direction of rotation.

Cheers,
Bill.

[Dave1360]

I'm very wary of disagreeing with Bill on anything Herald-related, but that's certainly not the case with the Delaney Gallay heater motor.  It will rotate the same direction irrespective of polarity.  Having said that, the Smiths motors may well be reversible as I've seen stickers to that effect on a few MG heaters, but I've not played with a Herald one.

Dave

[heraldcoupe]

Quoted from Dave1360

that's certainly not the case with the Delaney Gallay heater motor.  It will rotate the same direction irrespective of polarity.  

I don't have one to hand to check, but all those I've historically worked with have permanent magnet motors, both Delaney and Smiths. While I can't rule out a variant with windings in place of permanent magnets, it goes against the norm for a low-end motor,

Cheers,
Bill.

[Dave1360]

Interesting.  I distinctly remember having to unsolder the field winding terminals from the brush plate doo-dah when I took mine apart.  I'm fairly sure the old dead one was the same too.

Dave

[RobPearce]

I remember seeing an instruction to dealers (connected with customer reports of "running on") that strongly implied a change to permanent magnet motor in the heater. That might suggest there were some early cars with field windings?

[heraldcoupe]

Quoted from RobPearce

I remember seeing an instruction to dealers (connected with customer reports of "running on") that strongly implied a change to permanent magnet motor in the heater. That might suggest there were some early cars with field windings?

It's certainly worth a follow-up investigation when I get the time. I've hoarded about a dozen D-G heaters, just a matter of finding the time.

Cheers,
Bill.

[Bitumen Boy]

Quoted from Dave1360

...that's certainly not the case with the Delaney Gallay heater motor.  It will rotate the same direction irrespective of polarity.
Dave

It's a good few years now since I changed mine to negative earth, but I have a feeling that was the case with mine as well. Unless of course it had been the wrong way round to start with...