Category: negative earth

Triumph Herald Alternator Conversion (originally published in 2008)


So it begins, out with the old and in with the new(er)

Started with removing the dynamo (strangely enough:-))

Please note that the dynamo may foul the distributor.

Got around this by loosening it off and turning it away from the dynamo.

Be sure to mark the position of the dynamo before loosening so as not too put the timing too far out.

I put a small felt tip pen mark on an HT lead to line up with the LT lead of the distributor.

The dynamo was then removed.

Tried a few test fits of the altenator with the various parts of the existing dynamo bracket.

It would appear the best way to do this is to remove all the existing bolts etc (including the large one in the alternator and dynamo picture above) and replace them with two different size bolts and a large amount of washers to ensure all the pulleys line up.

The Herald fan belt will also now be too short, I’ll pick up an new one when I get the bolts.

Triumph Herald Positive to Negative Earth Conversion (originally published in 2008)


This is how I converted my Herald to negative earth.

1. Disconnect the battery

2. Remove the battery from the tray
3. Refit the battery around the “other” way

4. Connect the terminals in the correct
configuration for negative earth

5. Swop the LT connections on the ignition coil
to also reflect negative earth configuration
(you may have starting problems if you don’t)

Please go to this link where there is a basic
but very clever way of testing if the polarity
is correct. here is the test

6. Remove the large terminal from the dynamo

7. Take a piece of wire connected to the live
terminal of the battery and “flash” it on the
dynamo terminal a couple of times(it will spark)
The dynamo should now be repolarised
Refit the large terminal to the dynamo

8. Start the engine and check the charge rate
of the dynamo

In my case the dynamo charged prefectly first time, you may however need to flash it again if the charge rate is not sufficient.

My fuel gauge and wiper motor appear to work OK, I will therefore be leaving them alone!

The heater blower also appears OK, however I will swop the wiring over in the near future to see if there is any difference in the operation pos to neg.

Please don’t take this method as the same in all cases, follow these steps at your own risk 🙂

Coming soon “The Alternator”

Herald Update (originally published in 2008)


I have purchased an alternator for the old girl, and will shortly be fitting it and converting to negative earth at the same time.

Got a very good deal on the alternator, eBay of course!

I’ll publish the trials and tribulations of the conversion here in the future.

It looks as if only the heater blower, tank sender, battery and ignition coil will need reversing during the process, I think???