Tom Posted June 1, 2020 Report Share Posted June 1, 2020 Car is 1200 Herald. I dug out a bunch of Gauges I've horded over the last 20yrs! They are all the classic old Smiths gauges, Oil pressure, Charging and Temp. I also have a Thermostat housing with the temp sender screwed into the top. One thing I remember when my Herald was on the road was not not really being comfortable with the lack of info as to oil pressure, temp, electrical so I would like to make use of these gauges. I plan to mount them directly above the gearbox tunnel, in a bracket for all three hanging of the bottom of the dash. I have a splitter for the oil pressure gauge so I can retain the warning light and run the gauge. The ammeter is pretty straightforward it's the coolant gauge I might need a bit of help with. I'm hoping someone out there is a bit of an expert? My questions are.... 1. Is the sender specific to the gauge ie. do they have to be matched in some way? 2. Do I need a voltage regulator? 3. Does anyone have a wiring diagram for the coolant temp gauge/sensor/regulator? Thanks, Tom. Link to comment Share on other sites More sharing options...
SpitfireGeorge Posted June 1, 2020 Report Share Posted June 1, 2020 Hi Tom, When I did this on my Mk3 Spitfire I just connected the temp gauge to the existing sender in the thermostat housing and it worked perfectly. Cheers. Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 1, 2020 Report Share Posted June 1, 2020 Some people prefer a voltage gauge rather than an ammeter, ALL the current goes through the ammeter so some heavy cabling is required. But I do like an ammeter! Doug Link to comment Share on other sites More sharing options...
Tom Posted June 1, 2020 Author Report Share Posted June 1, 2020 I forgot to attach the pics of the stuff I have. I'm ok with the ammeter and oil pressure gauge, I even have the heavy duty cabling needed it's more the temp gauge wiring I'm not sure about and ideas for displaying the gauges? Link to comment Share on other sites More sharing options...
mishmosh Posted June 1, 2020 Report Share Posted June 1, 2020 The temp gauge simply needs a live feed taken from the voltage regulator and an earth. Link to comment Share on other sites More sharing options...
Tom Posted June 1, 2020 Author Report Share Posted June 1, 2020 mishmosh, so is it simply live feed from volage reg to the sensor ( thermistor ?) on the stat housing and then to earth? Just a series circuit? Would you be able to draw the circuit and post it? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 2, 2020 Report Share Posted June 2, 2020 are you sure this is a thermo bi metal gauge whats on the back temperature transmitters must match the design of the gauge bi metal stabilised GTR108 (slow moving needles moving iron (waggy needles ) not stabilised must use 121997 get them mixed gives silly readings on the stabiliser is marked B for battery and I for instruments you connect one gauge terminal to the stabiliser i and the other gauge terminal to the transmitter its the transmitter that earths to complete the circuit Pete Link to comment Share on other sites More sharing options...
NonMember Posted June 2, 2020 Report Share Posted June 2, 2020 8 hours ago, Tom said: mishmosh, so is it simply live feed from volage reg to the sensor ( thermistor ?) on the stat housing and then to earth? No. It's a "live" feed from the voltage regulator (or from ignition - see Pete's post above) to the gauge, then a wire from the gauge's other terminal to the sender. The sender body provides the earth connection through the thermostat housing. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 2, 2020 Report Share Posted June 2, 2020 11 hours ago, Tom said: ideas for displaying the gauges? I never liked putting them into the actual dash by cutting holes - too permanent, unless you either have an old dash that you can spare, or else can get one custom made. I used to have a row of three - oil pressure, voltmeter and vacuum gauge - in a mounting where the radio would hang under the dash, in front of the gearstick, and this is a very popular spot for additional gauges is you don't mind moving the radio elsewhere; but more recently I've used a pod that sits on top of the dash; if you use a 13/60 dash surround with the ashtray aperture on top you can put the cabling down through it, and attach the pod underneath, using brackets, without drilling; but if you don't have an ashtray on top you can pass the wires very discreetly down under the screen. In fact, you can even get gauges that use the ashtray slot, they just drop straight in and look very period, but sadly you can use only one at a time... which is why I bought three different ones... Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 2, 2020 Report Share Posted June 2, 2020 Colin! I new we had something in common! 3 gauges in the radio slot oil, vacuum and volts! I also have a 3 gauge cowl, but never used. I like the ashtray gauge, gives me an idea for the digital ammeter I have, which doesn’t match the others. Unlike old ammeters it has a sensor coil that goes around the battery wire, so no heavy cables required. Doug Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 2, 2020 Report Share Posted June 2, 2020 1 hour ago, dougbgt6 said: Colin! I new we had something in common! 3 gauges in the radio slot oil, vacuum and volts! I also have a 3 gauge cowl, but never used. I like the ashtray gauge, gives me an idea for the digital ammeter I have, which doesn’t match the others. Unlike old ammeters it has a sensor coil that goes around the battery wire, so no heavy cables required. Doug The three stooges of the gauge world! I debated - very briefly - fitting an ammeter but the gauge of the wiring I needed, and I was given a huge roll for the job, put me off. I could see the dashboard blistering, and bubbling, before my very eyes... the three Dashtop gauges I have are temperature, ammeter and 'battery condition' which I take to mean voltmeter. I bought them as a set years ago before realising they couldn't all be fitted to the same car... I have a small period rev counter for the Herald convertible which is a pod on a stem, so it will go on the dashtop close to the screen pillar so that the cables can be routed down the side, and it will just be freestanding on top. Here's a few suggestions for Tom based on cars I've seen over the years: 1 Link to comment Share on other sites More sharing options...
Tom Posted June 3, 2020 Author Report Share Posted June 3, 2020 Cheers for the info chaps, I quite like the Radio flanked by two gauges, I have two unused aftermarket switches to the right of the speedo I could fit one there to hide the holes in the dash. Pete - my ammeter pointer waggles around so does that mean it's a moving iron? If so how do I identify a 121997 temp transmitter? My gauge has one term marked T and the other B, so does B connect to battery +ve and T to the temp sensor? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 3, 2020 Report Share Posted June 3, 2020 most ammeters are moving iron , but doesnt matter as not using any of the stabilser ( unless you wanta fire !!!!) b battery T transmitter 121997 and GTR108 used to have different colour plastic insulation like a red or a green but most all seem black these days otherwise they look all the same , get it wrong and you get some funny readings , same you cant mix match fuel senders or you get some fun of the needle readings a thought if you fit a gtr108 to non stabilised temp gauges you get a very hot reading when its normal Ive had guys change an engine in desperation of over heating when it was fitted with the wrong one http://www.jamespaddock.co.uk/temperature-transmitter-vit-6-models-3 http://www.jamespaddock.co.uk/temperature-transmitter-10 gtr108 121997 pics c/o j paddock Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 3, 2020 Report Share Posted June 3, 2020 then if you have the OE numbers its in here somewhere !!! https://www.smiths-instruments.co.uk/temp-transmitters Pete Link to comment Share on other sites More sharing options...
Mjit Posted June 4, 2020 Report Share Posted June 4, 2020 On 01/06/2020 at 22:27, dougbgt6 said: Some people prefer a voltage gauge rather than an ammeter, ALL the current goes through the ammeter so some heavy cabling is required. But I do like an ammeter! Doug I seem to remember reading that it's an ammeter for a car with a dynamo but a volt meter for one with an alternator. Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 4, 2020 Report Share Posted June 4, 2020 Well yes, the reason is a lot more current from an alternator and some seriously heavy cables required when I put one on my GT6 alternator. The ammeter tells you the condition of your charging mechanism, dynamo or alternator. The voltmeter tells you the condition of your charged device, battery. I like the ammeter because it tells you straight away if there’s a charging problem, but by the time you’ve notice the volt meter’s a bit low it’s too late! Doug Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 4, 2020 Report Share Posted June 4, 2020 the dynamo/alternator ammeter/ voltmeter comes from the current wiring capacity required dynamo 25 amps alternator 40 to whatever. so it needs far more substantial cabling so for costs and fire possibilities they moved to just read the volts pete Link to comment Share on other sites More sharing options...
Mjit Posted June 5, 2020 Report Share Posted June 5, 2020 I though it was down to the fact the output of a dynamo was related to RPM so drivers needed to be more aware of their electrical load, so needed to see the current being drawn via an ammeter. An alternator can respond to changes in eletrical load independent of RPM so drivers are more concerned about the battery being charged or drained, whc=ich a volt meter will show you. Though I would also accept they are cheaper/lower risk to fit and the above is just the marketing BS used by the motor industry to sell the switch to the public. Link to comment Share on other sites More sharing options...
Tom Posted June 5, 2020 Author Report Share Posted June 5, 2020 Well my car has a Dynamo so I believe that is more suited to an Ammeter. I have all the very thick cabling, I think I took all this off a written off Sunbeam Rapier in a scrapyard in Derby about 25yrs ago!! Back to the coolant sensor/gauge. I dug through more of my bits and found 2 temp senders, I wired them up to a battery and the gauge and put them in a bowl and pour hot water in, I also had a glass thermometer in there. One sender read high ie. at 60degc the gauge read Normal and 80degc High. The other sender was bang on Normal at 80degc so I think I have a working setup! I still don't know whether I need a voltage stabilizer and exactly how it's wired up so if someone could let me know that would be great. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 5, 2020 Report Share Posted June 5, 2020 stabiliser has a feed from the ignition ,and its output feeds the gauges the case of the stabiliser(if original) must be earthed hence normally fixed o back of eg the speedo and its marked top as needs to be right ways up. terminals are male/female so on the line you cant wire them back to front no idea about electronic units Pete Link to comment Share on other sites More sharing options...
Tom Posted June 5, 2020 Author Report Share Posted June 5, 2020 Pete, I know this is an embarrassing question, but my battery a year or so ago, I recycled it. There is nothing on the leads to Identify polarity, I have had a brain freeze and I can't remember if my car has a positive or negative earth!!! I just remember I put the battery with the terminals facing forward and attached the leads, you could stretch the leads to the nearest terminal. How do check whether it's Pos or neg earth? Link to comment Share on other sites More sharing options...
thescrapman Posted June 6, 2020 Report Share Posted June 6, 2020 Tom, the positive terminal on the battery is larger diameter than negative. So look whether the earth lead connector is larger or smaller. Link to comment Share on other sites More sharing options...
Tom Posted June 6, 2020 Author Report Share Posted June 6, 2020 Cheers Scrapman, weirdly I've never noticed that! Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 6, 2020 Report Share Posted June 6, 2020 3 hours ago, thescrapman said: Tom, the positive terminal on the battery is larger diameter than negative. So look whether the earth lead connector is larger or smaller. I had to run out and check mine, but sadly they're all the same size. The straps are different, but not the terminals. Can you also check your coil - see whether the connection to the points runs from the + terminal or the - terminal, and this should tell you which polarity the car is. On positive cars the + side of the coil will go to the points. You can also convert to negative earth quite easily, it won't affect any of the major components, unless you have a positive radio fitted? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 6, 2020 Report Share Posted June 6, 2020 Measurements (at the base of the tapered terminal) are 17.5mm for the negative post and 19.5mm for the positive terminal. Japanese terminals (picture 2) are visibly narrower at 13.1mm for negative post and 14.7mm for the positive. pete Link to comment Share on other sites More sharing options...
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