Somebody will know on here, my new project has a Caerbont electronic Speedo, unwittingly, when dismantling part of the car, I pulled away a cover and found I had managed to mangle the bracket that held the sensor, the sensor survived my attempts to kill it,
My question is, the sensor is mounted next to the prop, where there are 4 small rare earth magnets glued to it, I'm trying to set this up for the sensor on a new bracket, mounted off the body rather than a heavy removable cover, "WHAT IS THE AIR GAP I NEED TO RUN?" between the magnets and sensor, I have had a look around and not found any info.

in simple terms as close as you can get without them clashing. realistically about 1 to 2 mm should work
try and mount it on whatever holds the shaft, rather than the vehicle body.