KiwiTR6 Posted June 12, 2021 Report Share Posted June 12, 2021 Hi all. Contemplating replacement of the ignition switch in my 73 CR as the current item is doubtful in my view with at least a 1V drop across it. I see that Moss offer several, but would welcome suggestions as to where I should look. Gavin Quote Link to post Share on other sites
Waldi Posted June 13, 2021 Report Share Posted June 13, 2021 Hi Gavin, have you tried spraying contact spray in the switch-contacts? This reduced electrical resistance in all my switches to almost zero. Waldi Quote Link to post Share on other sites
Nigel Triumph Posted June 13, 2021 Report Share Posted June 13, 2021 Another option would be to wire the ignition switch to trigger a relay that powers up the usual circuits. That should prevent voltage drop, and the old switch will probably survive a lot longer when only connecting a few milli-amps to energise the relay. Nigel Quote Link to post Share on other sites
KiwiTR6 Posted June 14, 2021 Author Report Share Posted June 14, 2021 16 hours ago, Nigel Triumph said: Another option would be to wire the ignition switch to trigger a relay that powers up the usual circuits. That should prevent voltage drop, and the old switch will probably survive a lot longer when only connecting a few milli-amps to energise the relay. Nigel Hi Nigel. Yes that was my original plan, although only a relay to supply the volt meter, which now that it works correctly, still reads 1V low. The ignition switch is a cheap no/name job and at least one of the terminals is a loose on the copper stud - probably my problem. I have considered stripping and cleaning it (as Waldi suggests - thanks waldi ), but I have an aversion to junk and the switch is a pretty important item in the scheme of things. That said, I think you have a very good point and that is to install a relay to control all of the circuits that are fed through the switch (the white wire). I'll almost certainly go ahead and do that but would also like to fit a decent switch. All of the aftermarket ones appear to have minimal or poor copper stud to terminal connections compared to the original factory item. There is the odd NOS switch for sale, but they are horrendously expensive and I need to convince myself that it's the best option in the long run. If I could find something a little less pricey and made to a better standard than what I currently I would probably go in that direction. Hence my question Gavin Quote Link to post Share on other sites
RobH Posted June 14, 2021 Report Share Posted June 14, 2021 There is absolutely no point in using a relay just to power the voltmeter Gavin - why on earth would you do that? You only 'need' relays on high-current circuits like headlights, cooling fan and fuel pump. A voltmeter takes so little current that a bit of wet string would almost suffice to feed it. A switch that drops 1V isn't 'doubtful' as you put it - it's knackered. How did you measure that volts drop though? Are you relying on the meter in the car or have you used a proper multimeter? Quote Link to post Share on other sites
barkerwilliams Posted June 14, 2021 Report Share Posted June 14, 2021 (edited) Gavin, I fitted a 120 amp relay on the ignition switch controlled circuit when I thought my ignition switch was getting a little tired. Now the ignition switch only powers the relay. Simple to fit in the washer bottle area near the other electrics. Has worked really well. Alan Edited June 14, 2021 by barkerwilliams Quote Link to post Share on other sites
KiwiTR6 Posted June 14, 2021 Author Report Share Posted June 14, 2021 12 hours ago, RobH said: There is absolutely no point in using a relay just to power the voltmeter Gavin - why on earth would you do that? You only 'need' relays on high-current circuits like headlights, cooling fan and fuel pump. A voltmeter takes so little current that a bit of wet string would almost suffice to feed it. A switch that drops 1V isn't 'doubtful' as you put it - it's knackered. How did you measure that volts drop though? Are you relying on the meter in the car or have you used a proper multimeter? Hi Rob. You're absolutely correct, but I have plenty of relays lying around (I'm in the trade) and my initial thinking related just to the voltmeter - which is a constant frustration . Voltage drop was measured with a Fluke multimeter a while back and all high current-draw items are already supplied via relays. The positive thing is that thanks to the comments I've received on this forum, I've now changed my thinking and will install a relay as Alan suggests to feed everything else triggered by my existing switch - which I'll either attempt to repair, or replace. Gavin Quote Link to post Share on other sites
RobH Posted June 14, 2021 Report Share Posted June 14, 2021 OK that makes sense - I understand now Gavin. No question with a Fluke! I think the problem with a replacement switch is that most suppliers stock will probably come from the same source even if the boxes look different, so that in reality there may not be too much choice. If you are going to fit a relay anyway, maybe it doesn't matter that much as the switch will have an easy life? Quote Link to post Share on other sites
KiwiTR6 Posted June 15, 2021 Author Report Share Posted June 15, 2021 2 hours ago, RobH said: OK that makes sense - I understand now Gavin. No question with a Fluke! I think the problem with a replacement switch is that most suppliers stock will probably come from the same source even if the boxes look different, so that in reality there may not be too much choice. If you are going to fit a relay anyway, maybe it doesn't matter that much as the switch will have an easy life? Yes, that seems to be the problem, they're all the same so a strip and repair is probably my best option. What I didn't make clear with the voltmeter relay setup was that it was just going to be a switch to supply the voltmeter with a direct feed from the battery to give me a true reading (within the capability of the voltmeter itself). Regards Quote Link to post Share on other sites
astontr6 Posted June 15, 2021 Report Share Posted June 15, 2021 7 hours ago, KiwiTR6 said: Yes, that seems to be the problem, they're all the same so a strip and repair is probably my best option. What I didn't make clear with the voltmeter relay setup was that it was just going to be a switch to supply the voltmeter with a direct feed from the battery to give me a true reading (within the capability of the voltmeter itself). Regards But has your voltmeter been calibrated? I don't think they are made for that sort of accuracy that you are looking for? Bruce. Quote Link to post Share on other sites
KiwiTR6 Posted June 15, 2021 Author Report Share Posted June 15, 2021 Yes Bruce, I got it very close to spot on a while back. A bit of black magic involved though - see the following post as to how I did it if you're interested. Voltmeter calibration success Quote Link to post Share on other sites
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