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MG MGB Technical - Horn adjustments

What is the procedure for adjusting a MGB horn? On the top of the horn are two adjustments: a tiny bolt with reverse threads and a large screw in the center. What does what?

Paul B.
Paul

Paul. The nut locks the screw in place. The screw is adjusted, upwards or downwards, until the horn produces a loud, horn-like sound. After that, the lock nut is re-secured to lock the adjustment in its proper place.

Les
Les Bengtson

But before you fiddle make sure you are getting a full 12v to the horn in the first place, i.e. no bad connections.

Up to 77 the horns had two wires each - a purple bring permanent, fused 12v to the horns and a purple/black bring a ground when the horn button is pushed.

Connect a voltmeter to the purple and you should see 12v. Push the button and you should still see 12v. If it drops more than 0.1v there are bad connections, check again both sides of the bottom fuse, holder, spades etc.

Connect a voltmeter to the purple/black and you should again see 12v. This time when you push the button it should drop to 0v. If it doesn't drop all the way again there are bad connections, check again at the sliding contact on the back of the wheel boss or stalk button as appropriate. Wheel buttons depend on the column grounding for a good signal, and it seems that collapsible columns can be a bit iffy in this department, as can after-market wheels. Stalk buttons seem to generally have a wired ground coming in which should be better.
Paul Hunt 2

Paul,

When you first go to adjust the horns, you may want to do unscrew the adjusting bolt (count the number of turns) and completely remove it and then clean the end of it and down inside the bolt hole. Lots of time rust and dirt builds up in this are and prevents the horns from making contact and "honking".

One of my horns was not working and I did this and it has worked fine every since - three years now.

Good luck.

Robert
Robert Browning

This thread was discussed on 11/10/2007

MG MGB Technical index

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