Badwolf Posted July 15, 2017 Report Share Posted July 15, 2017 I have a high note horn unit which appears to be faulty off a 1972 MkIV Spitfire. It refuses to make any noise and when put into circuit on its own makes the horn relay judder. Its friend, the low note horn works perfectly on its own using the same contacts. Using an electrical meter, there is no resistance reading across the terminal of the faulty unit. Is it possible to open the horn unit to repair it or am I just going to get a modern replacement? Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 15, 2017 Report Share Posted July 15, 2017 Bill at rarebits4classics used to refurb the old lucas windtone horns but really neeed to know what make and type you have thats failed originals were a variety of types then over the years anything could have been fitted some you can strip , some its mend it to destruction its generally a contacts gap, and corrosion that breaks the ciruit Link to comment Share on other sites More sharing options...
Badwolf Posted July 16, 2017 Author Report Share Posted July 16, 2017 Thanks Pete. There doesn't appear to be any indentifying marks on the failed unit except for "H" inside the trumpet section. The halves are rivetted so this one looks like it could be difficult to open. You are right about difference in units, the "L" unit has small bolt heads around it so that is probably the repairable type. Unless anyone has any other thoughts I will try drilling out the rivets to get inside or buy the one on ebay at the moment. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 16, 2017 Report Share Posted July 16, 2017 Last pair of nice red high , low from halfords for quite cheap and make a pleasant quality Wind toned blast, rather than Baa Baa. Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2017 Author Report Share Posted July 17, 2017 Got inside faulty unit to find that the rivet holding the internal connector to the external spade has broken. Hoping that is the problem. I will repair today and report back in case this helps any other members. Do you think anyone would be interested in my conversion of an original (but broken) push pump screen wiper switch to electric, or has this topic been 'done to death', even though I can't find it on the internet? Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 17, 2017 Report Share Posted July 17, 2017 I'm interested, although my handdraulic switch isn't broken, yet. Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2017 Author Report Share Posted July 17, 2017 Ok. Will start a new thread later with instructions and photos 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 17, 2017 Report Share Posted July 17, 2017 yes ive searched for the old lucas bell push switch that used to be used on the back of these wiper switches but never found one odd that i dont have one in my history box of switch gear from the70s Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2017 Author Report Share Posted July 17, 2017 Back to the horn unit. Reconnected internal wire to spade spade terminal and it worked... twice, then died. I'm sure this is something trivial but can't spot it. Any auto electricians out there with any ideas will be most welcome, otherwise its a trip to ***fords or a new pair from Paddocks!! Pete, is this the set you got.. http://www.halfords.com/motoring/car-parts/electrical-lighting/car-alarms-car-horns/ring-low-high-note-car-horns Link to comment Share on other sites More sharing options...
Casper Posted July 17, 2017 Report Share Posted July 17, 2017 If it has gone open circuit it is probably the contacts needing a clean. C. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 17, 2017 Report Share Posted July 17, 2017 yes they are the ones ,, gone up a lot since i got mine played with some 3ft long truck air horns that came back as warranty, ,,well these look fun under the bonnet but needed a 20ltr air tank charged to run them ,,need lots of volume to produce LOTS OF VOLUME sad Pete Link to comment Share on other sites More sharing options...
Badwolf Posted July 17, 2017 Author Report Share Posted July 17, 2017 Got it working!! For the moment... now the low note appears sad compared to it. Did a lot of reading up and simply looking at it before I finally figured out how it worked and that it had an adjuster which was solid due to years of paint. Works as a simple electromagnetic oscelator with the adjuster setting the gap for opening and closing the points to make and break the circuit. Cleaned the contacts and sprayed with WD40. I think that in putting it back together I put to much silicone sealer between the three sections, moving the post (which acts as a spring) attached to the sounding board to far away from the contacts. Time will tell if I have got it right, but will now try the low note. Thanks for all the help and input. Postscript.. I have freed the adjuster for the low note horn and after about a quarter of a turn the volume now matches the other, much to the neighbours enjoyment! I wonder how how many members don't realise that horns can be adjusted. I didn't and have had the car for over 30 years!!! Link to comment Share on other sites More sharing options...
Casper Posted July 18, 2017 Report Share Posted July 18, 2017 the volume now matches the other The volume is fine, but the frequency shouldn't match. From Wikipaedia: Horns can be used singly, but are often arranged in pairs to produce an interval consisting of two notes, sounded together; although this only increases the sound output by 3 decibels, the use of two differing frequencies with their beat frequencies and missing fundamental is more perceptible than the use of two horns of identical frequency, particularly in an environment with a high ambient noise level. Typical frequencies of a pair of horns of this design are 500 Hz and 405–420 Hz (approximately B4 and G♯4, minor third). although Hella offer different frequencies http://www.hella.com/hella-sg/assets/media/Hella_Horns_Brochure_LoRes.pdf C. Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 18, 2017 Report Share Posted July 18, 2017 ive said before we used to be involved with all sorts of testing on trucks and horns were once on the agenda there was when we were taken over by chrysler in the 70s a great usa manual of test procedures completely inappropriate to the UK but we had to go through the motions . we used cranfield aerodrome marked out the distance specified and on the basis we couldn't hear either picked the cheapest !!!!!! Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 22, 2017 Report Share Posted July 22, 2017 yes ive searched for the old lucas bell push switch that used to be used on the back of these wiper switches but never found one odd that i dont have one in my history box of switch gear from the70s I think I have one.... no idea how I acquired it tho.... Link to comment Share on other sites More sharing options...
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