NGK Spark Plug Connector Innards -- FYI

[DHeal]

I recently replaced one of the original NGK spark plug connectors on my 2014 RV-12 ULS due to its having failed the "pull-test". Apparently the little attachment spring inside the connector had weakened. No big deal to replace this connector. I thought the assembled group here would be interested in how the connector is constructed -- see photo below. The innards are encased in a hard plastic protective shell but I would still be careful pushing/pulling during the connector's installation to avoid damaging the tubular resistor.

 

[seagull]

I have made and replaced the little spring piece. It is made of music wire and wears in the area where it contacts the threads on the plug. You can use a flat blade screwdriver to unscrew the brass insert to access the “spring”. This fix will work for a while but what is wearing is the brass tube that this spring holds the plug threads against.
The new spring is on the left, notice the wear on the right one.

 

[seagull]

This is an exact replacement with a better rubber.

 

[Piper J3]

In addition to the retaining spring in the spark plug boot, the spark plugs themselves get a flat worn on the threads.