RogerH Posted February 17, 2017 Report Share Posted February 17, 2017 Hi Folks, last night I noticed that the horn on my 4A worked when going straight ahead but did not work with the steering wheel at any other angle. This morning I attacked the fault with my multimeter. This showed that the fault was at the lower rubber UJ. As you know there is quite a lot of car in the way - mainly the alternator. After a short struggle the alternator was out. Another test with the multiumeter showed that the fault was definitely there. Rather than break the steering shaft down I decided to put a link around the outside of the UJ. When finished I pressed the horn button and .............Nothing. On closer inspection of the upper UJ I found that the electrical link was broken (I wish I had found this before taking the alternator out,) I fitted another external link around the UJ - thankfully this now made a significant difference it now went .....toot. How could the fairly large brass 1/4" ring connector break off. The UJ goes round but nothing else - how could it flex and break. Roger Quote Link to post Share on other sites
tim hunt Posted February 17, 2017 Report Share Posted February 17, 2017 Just forget these earthing links on the couplings Roger and fit a spring loaded contact as below to connect the upper steering column direct to the body. This provides a reliable constant earth for the horn and it's worked for me for 45 years! Tim Quote Link to post Share on other sites
RogerH Posted February 17, 2017 Author Report Share Posted February 17, 2017 Hi Tim, yes, I have seen your previous posts regarding the slipping contact. However I have problems with slip rings on dirty/rusty surfaces. Although the 12V has a small current (100mA or so) - are we confident that there is no microscopic arcing. are we confident that this arcing is not causing microscopic cracking. are we confident that the steering shaft (it is not a simple mild steel) will not crack and fall in two. Electricity goes down copper wires fixed contacts and that is where it stays (except when it breaks). Roger Quote Link to post Share on other sites
tim hunt Posted February 18, 2017 Report Share Posted February 18, 2017 Ooer Roger, as a metallurgist (retd)you've given one more thing to worry about although the 50-year-old original steering column still looks fine to me. Tim Quote Link to post Share on other sites
RogerH Posted February 18, 2017 Author Report Share Posted February 18, 2017 Hi Tim, don't panic. It would take a fair bit of arcing and probably a decent voltage. Just one of my foibles. Roger Quote Link to post Share on other sites
ianc Posted February 18, 2017 Report Share Posted February 18, 2017 The answer is to smooth the contact area to a very fine finish, then coat it with Vaseline. This will ensure good contact and eliminate arcing. Ian Cornish Quote Link to post Share on other sites
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