[T3] Horns

[Dave Hall]

I like the idea of a bulb horn!

Polarity shouldn't affect our sort of horn, but our Type 3s (mostly?) ground
the horn circuit to the steering column when the horn bar is pressed, and
the horn whenever the ignition is on.  You wouldn't be able to use the
one-connector types unless you isolated them from the car body - they would
hoot continuously until they burned out!

The ones I've taken apart have had an electromagnet with a make and break
contact that causes an armature (piece of iron) to be attracted and
released.  This vibration is what you hear, amplified by the metal housing.

On some horns there's a screw externally to 'tune' the sound - worth trying
that first if so.  It may be under a blob of sealant, which needs digging
out and replacing after.

You may have to drill out rivets or undo screws (often well corroded in,
from my experience) to separate the horn and reach the works.  Often the
contacts just need cleaning, but if the electromagnet coil has burned out,
it's not going to be worth messing with.

Sometimes the contacts can be adjusted to make it work.

Some horns need a certain thickness gasket between the halves to operate
properly - the internal spacing can be critical.

However, there's nothing very sophisticated, so give it a go!

Dave
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of J. Jonik
Sent: 24 May 2015 02:32
To: type3 at vwtype3.org
Subject: [T3] Horns

Just tested five horns from my collection of VW stuff.  I used some wire
bits and the in-car battery and found that two worked great...the other
three didn't even try.
Why aren't the two-tab connector horns marked with which elec. tab is for
hot, and which is ground (earth) ?  I tried both ways, hot-ground,
ground-hot, and the non-responsive horns didn't work either way.   Did I fry
something to kill the horns?
The two horns that worked had only one elec. connection tab...the grounding
being as bolted to the bumper....but another of those one-tab horns didn't
work either. This refers to the Snail Shell shaped horns, not the round
ones. The round horn on the car, from my parts collection, worked fine to
get through inspection.

Questions: 
--  If a horn flunks this test is it a Dead Horn, ready for metal recycling
or an art project?--  Any way to fix...say, by opening up and cleaning etc?
--  Can any old 12 V horn from an auto parts store replace...if it fits
under the bumper?
Bentley book was no help in this area.

PS:  Though this problem means that Serious Performance Problems may be all
solved, still, in some or most states you can't Pass Inspection, or be
legally able to drive the car, unless the horn works.  A rubber bulb bike
horn mounted on the driver door won't cut it.




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