Servicing the horns 140/150/mk9

I have the original horns on a 140 and a Mk9. They are not very loud. The same horns on my 150 are much louder,
I know about the adjustment screw inside. Will this increase the sound level, or is there something else that I should do when I have them on the bench?

Peder,

After a longer period of use there will be some damage/corrosion/dirt within the system. In fact the adjustment screw at the back of the horn is only intended to set the correct Amps for the horn, although sometimes it may help when the points have some wear. Often the only solution is to dismantle the complete horn and reset the air gap between armature and coil to the correct value (different for high and low note horns). This is a very time consuming job, providing you succeed in getting the screws removed from the Zamac housing in the first place.
So start slightly turning the screw at the back of the housing before you start this major operation. May be you’re lucky,

Bob K.

This was a big proviso in my case. After months of soaking in various solutions, applying heat and buying an impact screw driver, all I succeeded in doing was cracking the housing by the screw holes. I have pulled a lot of rusted screws and bolts out of this car, but these were the worst. They beat me.