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Old 3rd December 2020, 17:56   #1
OddSox
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Default Twin horns.

Can anyone advise how the two horns on the 75 are wired?

They make a fantastic sound and really make folks aware.

I own a little fiesta and it only has one puny horn and it makes an awfully unimpressive 'beep' instead of the blast you get from the 75.

I had a spare horn and wired it from the body (Earth ) and to the other horn.. but it sounded absolutely stupid.!

Where did i go wrong?
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Old 3rd December 2020, 18:33   #2
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Horns are normally High and Low tones (the twins on the ZT/75 are 500Hz and 400Hz) so ideally you would want a matched pair for them to sound more melodious, or at least a high and low tone.

Another factor is the type as well, they could be high frequency type; which do tend to go 'beep' or proper 'windtone' horns which do give a much better 'parp'.

If you're wiring them up, then you also need to make sure they are connected in parallel so they both see 12V, make sure you haven't inadvertently connected them in series, in which case they've only see 6v each.
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Old 3rd December 2020, 20:26   #3
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Also the wiring might not be man enough to have to carry double the current.
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Old 4th December 2020, 10:20   #4
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Make sure that the wiring is up to carrying the current for both horns. (wire in paralell or they'lls sound rubbish).
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Old 6th December 2020, 23:48   #5
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High & low tone horns are the same. The back of the horns have an arrestor screw, that alters the pitch/tone of the horn. No point in buying a low or high tone horn, use either. Remove the sealant covering the arrestor screw, and adjust the pitch to whatever tone or Db you want, just as the factory does, and pop some sealant over the screw. The 400/500 markings are first used on the assembly line, to tell where to set the arrestor screw
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Old 7th December 2020, 10:23   #6
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Quote:
Originally Posted by Devilish View Post
High & low tone horns are the same. The back of the horns have an arrestor screw, that alters the pitch/tone of the horn. No point in buying a low or high tone horn, use either. Remove the sealant covering the arrestor screw, and adjust the pitch to whatever tone or Db you want, just as the factory does, and pop some sealant over the screw. The 400/500 markings are first used on the assembly line, to tell where to set the arrestor screw
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No high and low tones are different, one coils clockwise and the other anti-clockwise for a start. The trumpets on windtones are I suspect different lengths as well between high and low (they certainly are on the old Lucas ones). The screw that is often visible is to adjust contact gaps.

Not sure about the high frequency horns, but I suspect the tone discs are also different between high and low.
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Old 7th December 2020, 18:10   #7
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Post 5 or post 6 ?????????????????????


Should I spin a coin ??---
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Old 9th December 2020, 16:10   #8
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Thank you all. i'm definitely the lay person here when it comes to wiring. It's just one of those things i dislike intently and being colour blind doesn't help.

Iv'e seen these on ebay, they're off an MG TF and look a lot like the ones on the 75.

https://www.ebay.co.uk/itm/Mg-Tf-Mgf...s/224267086462

Could i mount these twin one's and just connect the wire (where it's been cut) to my original single horn connection - would that work?
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Old 9th December 2020, 16:42   #9
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Quote:
Originally Posted by OddSox View Post
Thank you all. i'm definitely the lay person here when it comes to wiring. It's just one of those things i dislike intently and being colour blind doesn't help.

Iv'e seen these on ebay, they're off an MG TF and look a lot like the ones on the 75.

https://www.ebay.co.uk/itm/Mg-Tf-Mgf...s/224267086462

Could i mount these twin one's and just connect the wire (where it's been cut) to my original single horn connection - would that work?
Yes, that would work, there's likely to be only a single positive and negative wire in the loom, just looped to the second horn in the loom.

The only thing might be worth checking whether an MGF uses a horn relay or not, sometimes with twin horns because they draw higher currents they may have a relay in the circuit (can't remember if the 75 does or not)
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Old 9th December 2020, 16:56   #10
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Quote:
Originally Posted by OddSox View Post
Thank you all. i'm definitely the lay person here when it comes to wiring. It's just one of those things i dislike intently and being colour blind doesn't help.

Iv'e seen these on ebay, they're off an MG TF and look a lot like the ones on the 75.

https://www.ebay.co.uk/itm/Mg-Tf-Mgf...s/224267086462

Could i mount these twin one's and just connect the wire (where it's been cut) to my original single horn connection - would that work?
A horn relay would ensure that both horns can work at their maximum output. ( Would take the load off the standard fuse too. )
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