Dynamo housings, a few more thoughts

- by Ron Hayhurst

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Last month Ian gave details of how the different types of dynamo are mounted on coil engines. He showed how the long bolt at the rear of the housing could trap a groove in the dynamo end cover, when attempting to remove it, and that the long bolt obviously had to come out first.

Although you might want to avoid choosing one of these dynamos, a simple mod can be made which will allow it to be fitted to any of the coil engines from 1930 onwards.

image 1

As there is plenty of metal in this grooved cover it is a fairly straight forward job to take off metal between the bottom of the groove and the end of the alloy plate. The picture shows a typical result of initial attack with an angle grinder finished off with a bit of judicious filing.

image 2

The Austin factory must have realised the pain caused by the groove and later dynamos had a conical end, as shown in the second photo, which cleared the bolt.

I find it is also well worth while replacing the long bolt with a long stud. This saves wear and tear on the thread into the aluminium crankcase. A little wriggling of the housing is needed when threading it over the stud as it catches on the cylinder block.

Also, remember to allow a little slack in the nose cone bolts when bolting the housing on to the crankcase. This is to allow the joint on the top face to properly align with the face on the crankcase. The nose cone can then be finally tightened.


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