Tuesday, 6 July 2021

Austin Seven special broken dynamo bearing

I noticed a strange noise while driving the Seven. It seemed to emanate from the front of the engine. 
After removing the fanbelt I found that the itself was fine, but the dynamo definitely was difficult to turn and the front bearing seemed shot. I keep a spare dynamo with the Wolseley, so I decided to fit that. Of course the broken dynamo will be rebuilt, so I'll have a spare available.  
I must say I had forgotten how compact I had built the whole thing and it was a bit more involved to remove the dynamo. To reach the bolts I removed the exhaust pipe and I drained the water from the radiator and I removed the radiator, hoses and pipes to reach the front bolt.  
With the exhaust, waterhose and dynamo out. I could tilt the radiator and the headlights forward. 
It looks a bit strange, but now I can remove the broken dynamo. 
With the the new dynamo fitted, the belt would not fit. I had moved the dynamo forward a bit in an effort to improve alignment of the belt on the pulleys. 
I got a slightly longer belt and all seems to fit well now. There's only the water hose to refit.
It's all coming together again, but after start up the dynamo would not charge. The charging light just flickered on and off. Then I remembered the Wolseley has a positive earth system and this Seven has a negative earth system. I changed polarity on the dynamo by removing the wires and touching the Field connection with a positive wire from the battery. After reconnecting all wires the car stared up fine, the ignition light went off and the charging system worked correctly, so now we're ready to roll again.