Squariel Dynamo Rebuild Part 2

Squariel dynamo rebuild part 2 leaves no room for ambiguity for this weeks blog. John from hobby mechanics supplied me with a 5BA tap and some screws. It then took Aus Post 2 weeks to bring the 25 odd kms to my place. The result led to those famous last words “this job won’t take long”.

Ariel Square Four Dynamo

Lucas – The Prince of Darkness

Basic testing

I did some basic testing of the armature with my multi-meter. Basically, just checking continuity and confirming that there were no shorts between the commutator segments. I probably should replace the field windings. This may turn into one of those regrettable decisions. However, they checked OK for resistance, so I have left them be. Time will tell of this is a myopic decision.

False starts

When I stripped the generator/dynamo down, I had a bad head cold. Hindsight being a wonderful thing, I did not take my usual array of pictures and sketches. Perhaps I should have. A bit of head scratching and a couple of false starts later, we were making headway.

Lucas Dynamo Serivce

Ariel Dynamo Repair

5BA Threads

My 5BA tap did its job (thanks John!) and I was able to relocate the field winding ground wire. The rest of the assembly was straight forward and was a reverse of the strip down.

4GMK2 Electrics

Lucas you are my light

Motor testing

One job that I was not able to do was to “motor” the dynamo/generator. This is done to set the polarity of the device so that the regulator can do its job in supplying charge to the battery. To do this, we bridge the F (Field) and D (Dynamo) terminals. Because the Ariel is positive earth, we connect the negative lead to the F/D bridge. Now touch the positive lead to the body of the dynamo and it becomes an electric motor. This sets the polarity of the dynamo/generator and it is ready to install. To change it to a more modern negative earth, simply reverse the wires and repeat.

Ariel generator

Lucas C35SD Dynamo

Next steps

What is next? The big-ticket elephant in the room is the engine. I have pulled it down. I know what needs to be done. Next step is to start purchasing the necessary parts and visit the bank manager. Oh, so how is the fuel tank coming along you ask? Don’t ask!


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