OVERDRIVE OVERVIEW

The next time you remove the transmission tunnel cover of your big Healey – or perhaps the first time if you’ve never done that before – be sure to check the brass data plate on top of your overdrive.  It looks like this:

The potentially interesting thing about it is the “percent overdrive” the unit is.  This one, from a BN2, is a standard 28 percent overdrive.  The way to tell that is by the first two digits of the serial number:

The print is small and if you’re like me you may find it easier to take a phone-camera picture of it, such as this one, and then enlarge that image.  Note the serial number begins with 28/, so it’s a standard 28 percent overdrive.

Maybe your Healey has a rare, non-standard unit and you don’t even know it.  Now you can easily find out.