Hi,
I don't have a Clio horn to hand, but generally they are fairly simple items. You will have two connections which should be clean and free of corrosion. You may also have a screw on the back, this can be screwed in or out to control the way the diaphragm vibrates. You could try adjusting this to increase the volume. You can't generally dismantle horns, so if you can't make it louder; ditch it. If you decide to purchase an aftermarket horn from a parts supplier, you will usually get a decibel rating on the packet.
Cheers now
Ken Chapman
May 2007
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