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MG TD TF 1500 - Horn tone

Gentlemen,
I've checked the archives with no suggestions for my problem. Both of my TF horns work, but together sound somewhat like a moose in heat hiding somewhere in the back of a closet with the door closed. They are very low volume wise, and do not vary significantly in tone, so that you can't really tell that there are two of them on two different pitches. Is there some tweaking that can be done with the innerds to rectify the situation?
Gene Burgess

the workshop manual page n.14 and n.15 describes adjustment for wear. someone on ebay has been selling a reprint of a lucas manual. tom
tm peterson

Gene,

First, before ANY adjustments are made, be sure the contacts are clean. Run a piece of wet-or-dry through the closed points several time, one side of the points at a time. Clean both sides of the points. Then retest. If they are still weak or woefully out of tune, be sure the activating rod is free. This is the thin metal shaft that opens the points when the horn has power applied and the electro-magnet is energized. Work it back and forth several times and apply just the barest dab of penetrating oil. You may have to split the case so the diaphragm is loose from the horn in order to check the operation of the activating rod.

Under no circumstance disassemble the stack of insulators and brass contacts. This is totally unnecessary. I can't tell you how many horns I get for repair where someone has disassembled the insulators and then forgot how they go back together.

Then, and ONLY then, the points may be adjusted by loosening the lock nut under the lower half of the points (the one closest to the diaphragm). Then adjust the points by varying the nut under the above-mentioned lock nut. A fraction of a turn should be all that is necessary. Then retighten the lock nut and retest. You may have to repeat this adjustment several times to get the optimum volume and tone. Go for the optimum volume, as you can't adjust the tone by any significant amount.

If all this fails and you want me to rebuild the horns, or if you have any other questions, let me know.

Cheers,
Lew Palmer
Lew Palmer

don't waste $9.95 on that advertized piece of toilet tissue. I did and it is basically useless. More info is in service manuals than there.
Sandy
conrad sanders

Those horns, which can be found not only on TDS but also on other British cars, are very loud and the pitch of each is distinct, they sound the musical interval of a major third, which is the ratio, between two notes, of 5/4, as between E and C. If not, you have the wrong horns.

Denis
Denis L. Baggi

See this site for horn repair
http://www.vintagemg.com/ArticlePDFs/THorns1-2.pdf
Bob

Thanks, fellas. Gene has described my TF horns beautifully and Lew has told me what to do to fix them.
Many thanks.
Peter Daley

Gentlemen,
You've come through again! I'll get to work on the horns over the next day or so and keep you posted as to how I make out.
Gene
Gene Burgess

Blimey Denis: if you can tune a car horn like that I wonder how your living-room stereo sounds .....8^)
Cheers,
Nick, 52TD/63midget.
Nick

I worked on my horns today. I did everything and the thing that really got the sound out was hitting the horn on the pavement, side first. Hitting the horn with a BFH might be the best thing you can do for it. Once you get it vibrating nicely, and the dogs start barking, it seems they keep on for a while. I'm going to try to exercise mine more often now. And if they stick again, the first thing I'll do is hit the dam thing on the side with a hammer. No, I'm not gonna say that the dogs had anything to do with it, hehe.
Tom

Hi Gene,Check the TF's Horn brackets which attach the Horns to the chassis extensions-they are often cracked giving rise to "moose" sounds!Cheers Rob.
Rob. Grantham

Gentlemen,
Crawled under the TF today and pulled the horns and removed their tops. A few nudges up and down on the rods with a pair of needle nosed pliers, and 3 or 4 passes between the points with some 600 grit wet/dry paper, has trans formed the sound dramatically.
I can now compete with the tuner kid around the corner when he goes by with his stereo turned up to mass destruction. Thanks to everyone!
Gene
Gene Burgess

To Nick:

In fact, that's not the way how yuo tune pianos, because since the 18th century you use the "tempered" system, namely, each semitone is the 12-th root of 2, the octave. But horns, trumpets, woodwinds etc. are a different matter and respect the harmonics, namely, 5 times the frequency of a fundamental is two octaves and major third above, like high E over C, and you bring it down two octaves by dividing twice by 2, hence 5/4. That's elementary acoustics, useful with MG horns!

Denis
Denis L. Baggi

Denis,
You continue to impress me ! I'm a music lover myself but only as a listener (don't play any music instruments except for my angle-grinder which is a bit off-tune lately...8^). I never thought of car-horns to be "tuned" just thought they made an awful lot of noise. However: I was amazed when I discovered that Lucas indeed tuned their horns (according to their service manual). It almost seems a pity to hide them under the bonnet of the TD !!! Am I right when I say it's up to the operator to decide HOW they sound. i.e."adagio", "allegro con brio" or "vivace"....8^)
Da capo,
Nick, 52TD/63Midget.
D.G.J. Herwegh

Dear Nick, I am sorry to say I believe you are not right! There is little you can do with those horns, but fix them and get them to sound the best they can.

Incidentally, I have heard the horns of the export TC for the US and it's a minor third! 6/5, somewhat like between E-flat and C. Detroit horns are a major third like TD's, some Italian cars have a diminished fifth, an especially dissonant interval about the same as the square root of 2 - hence an irrational ratio which the ear dislikes!

Happy to answer further questions (about MG's of course!).

Regards, Denis
Denis L. Baggi

I always thought the Lucas horns were so pleasing that no one would get out of the way for them. I had a Fiat that had those nice air horns as standard, but do you think they woke up the guy on the freeway in the left lane? HA! We need a link to the Onstar system to send them an email. "Sorry to bother you, but you're not going as fast as the car behind, would you please look in your mirror?"

The Lucas ones are great for getting your friend's attention when you're waving.
Tom

This thread was discussed between 02/08/2005 and 07/08/2005

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