11 replies to this topic

[JoneseyBoy]

I've been given a double air horn and a cylinder wich I guess is the compressor. How do I go about fitting it

[miniweights]

I'm not a sparky but here’s what I did.

Take the existing + cable from the factory fitted horn, and connect it to the 85 connection on a 30amp relay. Then connect the – cable from the factory fitted horn, and connect it to the 86 connection on the relay and also the – connection on the compressor. Then fit a cable from the + connection on the compressor to 87 connection on the relay. Then fit a cable via the fuse box or from a + 12v supply via a 30amp fuse to the 30 connection on the relay. All the additional cable I used was 12 gauge.

[JoneseyBoy]

My horn don't have a - its just got a +

[lrostoke]

I did this a few years ago

This guide will work for both twin tone air horns and musical, main difference you will need to find room for all the horns on a musical set..

1st find a good place to mount the horns. I chose under the n/s wheel arch because the slats in the inner wing made an ideal place to clamp the horns to...I made a bracket to mount the horns to first, then clamped that bracket to the slats. Make sure if you mount them here they do not foul on the wheel, check wheels at full lock both ways



Next the compressor unit, if you use the tubing that comes with the kit you will have a limit how far from the horns you can mount the compressor. I was lucky there was already a hole in my bulkhead sealed with a gromet that I was able to utilise for the mounting of the compressor



Next wiring find a suitable place for the relay, again no servo on my mini so I have a nice open space to mount it



On the compressor you will find two terminals postive and negative, the positive you run a cable from that to a terminal marked 87 on the relay.
The negative I connected to the same bolt that mounts the compressor to the bulkhead.

Next on the relay terminal 30 you connect to a permant live feed, the live side of the starter solenoid is a good source for this, I've been a bit rough here in that I ran out of ring connectors so the cable is clamped by the two ring terminals already on the solenoid, I will replace this once I buy some ring connectors. You will need to fit a 30 amp inline fuse on this cable.



Terminal 86 on the relay goes to earth, again Ive used the car body, the black wire attached to the mounting screw of the relay



Finally Terminal 85 goes to the horn switch, easiest way of doing this is to unplug the spade connector that plugs into the existing horn and plug your cable you have attached to terminal 85 into the wire that went to the horn.

[Dan]

Regarding what was said above, don't use the horn earth on a car with a two terminal horn to earth the compressor. Earth cables for any item carry the same current as the supply cables, the standard horn earth may well not be up to the current of the compressor. It's fine to earth the relay with it if you want, but not the compressor. Anything that is heavy duty enough to need a new circuit to be established needs a complete new circuit including the earth.

[cooperrodeo]

I used to have an air horn in my dim and very distant youth. It was useless as a warning device because of the delay between pressing the button and the compressor getting up to speed.

[Dan]

Then it had the exact problem that I am referring to, undersized cable on either the supply or the earth! Given cable that can handle the substantial load a compressor dumps onto it at startup, the compressors reach speed very quickly. There shouldn't really be much of a noticeable delay.

[lrostoke]

No delay on mine and its loud

[JoneseyBoy]

ok ive wired it as above but the compressor wants to stay on ? what have i done wrong

[JoneseyBoy]

Sorted it was a naff relay and thee is no delay in it either

[toplessmini]

Do the "snail" type horns sound any think like the twins fitted above?

[Lewis998]

Sorry for the bump but it is on topic, where is the stock horn ?