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MG Midget and Sprite Technical - More horn trouble

Rather than hijack someone elses thread again... :o)

I've got twin airhorns in the frog. Well, that's what they look like. What they sound like is a squeaky dog toy being trodden on by a pixie, or perhaps one of those little trouser coughs you have to be really careful about the morning after a night on the beers and a curry. Even Noddy would be mortified, although Taz seems to think it suits the character of the car, the cheeky mare.

As far as I can tell the hoses twixt compressor and horns are okay, it just seems like the airflow is akin to a mouse's death rattle, so I assume it's goosed. Or maybe it's a voltage issue?

What would people recommend for a replacement? Are those disc-like (diaphragm?) horns any good? How about the also-somewhat-disc-like airhorn type? I'd quite a like a train horn kit but space is at a premium as you can imagine ;)
Jordan Gibson

Jordan, I installed two Fiamm horns of the type linked on my midget, fit just behind the grill and are pretty loud. http://www.fiammamerica.com/Product.asp?ProductID=167
In the photo you can just see the chrome grill of the horn to the left of the driving light. One on the other side to match.


Bill Young

Try a little 20/50 in the compresor air intake...

A
anthony

Jordan.

There should be a lubrication point on your horn motor, if it's dry then there's no wonder they don't work properly.

When I read your thread title 'More Horn trouble', I feared the worse, how could a Girl like Taz not do the trick.... lol

Mark.
Mark T. Boldry

Well that's two votes for a drop of oil and a decent suggestion of what to try if that don't work.

I love this BBS :o)
Jordan Gibson

Make sure electrical connections are shiny clean.
Tom

Jordan. Just a thought prompted by Tom's suggestion: Are you running the horn through a relay? They do tend to draw a lot of current and as such can burn out switch contacts. Best to run the wiring through a relay. Nick V should be able to assist if you have trouble.

Mark.
Mark T. Boldry

It's a FIAMM twin trumpet set. I ran a bit of oil through the compressor last night and it's certainly better. I think part of the issue though is that it's fired off a push-button under the dash rather than the steering wheel horn push. You can tickle the switch and still get a bit of a half-hearted squeak, or give it a good jab and it'll now give the full blast. Presumably via a relay it'd be all or nothing, which would be better.

It doesn't help that the return spring on the button is quite strong so finding it in a hurry and giving it a good strong press isn't that easy to achieve if one is reacting to a hazard.

Think I'll look into hooking the steering wheel push back up, via a relay as you suggest. I want to see about installing a map light and an accessory socket too, so probably worth tackling all together.

Jordan Gibson

Well, the fact that your push button doesnt give all or nothing means that the switch contacts are burnt, meaning they have a high resistance on their surface and its not until you really squeeze them together that the switch is really closed as such. When installing a relay in this situation its best to install a load resistor across it so that you still pull a bit of extra current through the dash switch and not just that drawn by the relay coil - this helps with switch self cleaning. So in summary: too much current = burnt contacts and symptoms you state, too little current = dirty switch contacts and evetually the symptoms you state! Need to find the middle ground! You know where I am if you need some help! (that list must be getting long now)
Nick

Thanks for that Nick. Not a clue how best to wire in a relay - any references?. Also while you're here, do you have a fuel pressure guage I can borrow to set up my FK regulator when I've got it fitted?

I've asked about the sound level meter and using it here at work shouldn't be a problem, although I haven't yet suggested borrowing it unattended to use on a weekend - gotta tread carefully with these serious types we've got here ;) Will advise further on that one.
Jordan Gibson

Yep got a fuel presure guage.

Didn't you want the marbles in your tank investigated too?!!

I'm currently bidding on a sound level meter on ebay. If i win it, we can all have a go pre-croft, however if it turns out mines no where near illegal, I doubt yours will be. Tony's might be close though!

Nick

Wire a relay for the horns?

Assume the relay is at the front of the car, for best use of existing wiring.

Take the existing purple live wire and connect to the relay coil +ve and switch +ve. The coil -ve is connected to the purple to the horn switch on the steering wheel. The switch -ve goes to one terminal each on the horns; other terminal of the horns to earth.

HTH

A
Anthony Cutler

This thread was discussed between 24/06/2008 and 26/06/2008

MG Midget and Sprite Technical index

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