Quiet horns. Dual Lucas windtone.

PostPost by: Ashley68 » Wed Feb 22, 2012 10:21 pm

I've done some digging around on here and found out a good deal about this issue but there are one or two things I'd like to understand before I apply a fix. They work fine if you take the connection that goes to the horn push directly to a good ground. So the problem resides with the push button. Here I found that the braided connection in the horn push pencil had just about frayed through (fell out in two pieces!) so I repaired this with a piece of similar copper braid I had at work (checked it doesn't foul the spring and the length when assembled is 65mm). All the connections are well soldered, no dry joints, no flux residue etc and even metered it and have good continuity across it.

The horn is still quiet.

Took the push button out and shorted the end of the pencil out to ground in the steering wheel...still quiet.

Is there a suspect connection from the column to chassis ground I've missed, or another wearable part I've overlooked? I've also metered between the steering wheel and a known good ground in the engine bay and have good continuity.

What I do know is that horn push button would be capable of switching a relay, I've tried it. I'm familiar with the wiring for this and can use most of what's installed with the addition of 2 or 3 more wires. Is this the preferred fix or should I be doing something else?

I'd be very grateful for any hints! :?

Ashley.
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PostPost by: ardee_selby » Wed Feb 22, 2012 10:38 pm

Ashley68 wrote: I'd be very grateful for any hints! :? Ashley.


A couple of things you didn't specifically mention:

1.0 The "jumper" wire that bridges the two halves of the flexible joint OK?

2.0 Not all manuals show it...but an earthing wire from rack to chassis rack mounting point OK?

HIH - Cheers Richard
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PostPost by: collins_dan » Wed Feb 22, 2012 10:41 pm

When I switched from the original airhorn to a louder horn, which require more juice, it required a relay.
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PostPost by: gjz30075 » Thu Feb 23, 2012 1:34 am

If your steering joint is an original type, the upper half is isolated from the lower half with rubber insulators so there needs to be a jumper wire to connect the halves. That's part of the grounding. You might also have to ground the rack itself.

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PostPost by: Ashley68 » Thu Feb 23, 2012 9:21 am

Some interesting comments here...I did actually find an earth connection made behind the bolt that secures the horn to the inner wing. I thought it was odd at the time as the horn case doesn't need an earth connection. Having learnt what I have here now I wouldn't be surprised if were the connection intended for the rack securing bolt (not sure where it is but I expect it's not far away!). I was also surprised that the wire seemed to be far longer than it needed to be if indeed it did need to be connected under the horn fixing bolt.

This evening I shall try connecting the horn push pencil directly to earth in the engine bay and see what that brings. If that works I shall connect it to the lower half of the column and work back towards the push button and see where the ground connection is lost.

1.0 The "jumper" wire that bridges the two halves of the flexible joint OK?
Yes it's fine. It was frayed in two but I replaced the connection with a new piece of braid.

Thanks to all so far!
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PostPost by: ardee_selby » Thu Feb 23, 2012 9:35 am

This is how the rack earthing is shown in some illustrations:

Rack Earthing.jpg and


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PostPost by: elansprint71 » Thu Feb 23, 2012 10:31 am

Daft question but you have tried wiring live and earth directly to the horns to see how well they work?
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PostPost by: Ashley68 » Thu Feb 23, 2012 10:43 am

It was one of the first things I did when I had them on the bench. They work very well despite their age!
When reinstalled I have also taken the connection that goes to ground via the push button directly to earth in the engine bay and they also work perfectly under those circimstances. So I'm left with the earth circuit via the steering column as the main suspect at present.
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PostPost by: ricarbo » Thu Feb 23, 2012 3:14 pm

You say "It was frayed in two but I replaced the connection with a new piece of braid" for the pencil connector in the steering wheel, but there is also the link wire across the two halves of the universal joint lower down the column. when asked about that you said, again, "It was frayed in two but I replaced the connection with a new piece of braid." Does this mean you have replaced two wires or, as I suspect, just the one in the pencil connector? If both these connections are good I would expect it to work, unless you are trying to pass too much current, meaning a relay is needed for your application.
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PostPost by: Ashley68 » Thu Feb 23, 2012 4:29 pm

Sorry, misread your question. I haven't got to finding that link between both halves of the column. Only became aware of that today. I'll be checking tonight. The pencil is only part I've repaired so far.

They're standard horns so I'm hoping that the solution will be one of the suggestions made here.

Thanks again.
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PostPost by: gjz30075 » Thu Feb 23, 2012 4:41 pm

Ashley68 wrote: I haven't got to finding that link between both halves of the column.


Look for a wire on the steering coupler down by the rack. The wire will connect the two halfs of the coupler.

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PostPost by: elansprint71 » Thu Feb 23, 2012 5:11 pm

I reckon you've got your night and day horns mixed up- apparently it is still illegal in England to sound your horn after 7pm. Lucas made some silent horns to use at night. :roll:
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PostPost by: collins_dan » Thu Feb 23, 2012 5:23 pm

Also, depending on the type of flexible joint you have on the steering column, there may need to be a strap there as well. Dan
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PostPost by: ardee_selby » Thu Feb 23, 2012 5:39 pm

ardee_selby wrote:
Ashley68 wrote: I'd be very grateful for any hints! :? Ashley.


A couple of things you didn't specifically mention:

1.0 The "jumper" wire that bridges the two halves of the flexible joint OK?

2.0 Not all manuals show it...but an earthing wire from rack to chassis rack mounting point OK?

HIH - Cheers Richard


As I said Ref: 1.0 above

earth bridge.jpg and
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PostPost by: gjz30075 » Thu Feb 23, 2012 7:10 pm

A pic is worth 1,000 words! Thanks Richard.
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