Vibration Harmonic Damper-original style-less inner metal timing plate on A Plus.
Alternative is 12A367 and C-AEG454
It might surprise you to know that the A-Series engine has a vibration problem! But the factory had known it for years and designed a "damper" to help absorb or counter balance this problem. The nature of the engine results in vibration that can result in crank bearings being knocked out! The uncomfortable feeling of the engine vibration is a problem, but losing the bearing can be a disaster.
The most common damper is this "one-piece" affair that is actually a pulley with a outer metal ring connected to it with a special vulcanized rubber. Great, simple design. But this same design has an inherent problem- as the rubber dries-up and/or is exposed to oil, dirt, etc. it cracks and stops "dampening".
In severe cases this one piece affair has actually separated at the rubber resulting in all kinds of destruction! Check the back side of your damper the next time you are in the engine bay- it could scare you!
This fitted many of the A series cars including Austin /Morris 1100/1300 range, midget and sprite and minis up to the MPI in 1996.
Unpainted stock are sprayed in silicon spray.