Ian Vincent Posted February 2, 2021 Report Share Posted February 2, 2021 I have a standard 30amp ammeter in my TR3a and a 40 amp Kubota Denso Alternator. It all works perfectly well with nice chunky wiring so I don't want to change anything but.... the ammeter needle at rest with everything turned off is not centred. Even if I disconnect the battery it doesn't centralise. It has always been slightly 'off' but it seems to be getting worse and indicates (wrongly) a slight discharge. I say wrong because with the battery taken out of circuit, there can't be any current flowing. I've searched the forum to see if there is a way of adjusting them - without success, does anyone know if there is a way of adjusting a centre zero ammeter back to zero Quote Link to post Share on other sites
Steves_TR6 Posted February 2, 2021 Report Share Posted February 2, 2021 When i reconditioned my 6’s guages i found that the rest position of the needles of most of them can be ‘set’ with a tiny lever. i didnt rebuild an a,meter but suspect it works the same way? might be worth taking the face off to have a look, if you’re brave ! steve Quote Link to post Share on other sites
Mick Forey Posted February 2, 2021 Report Share Posted February 2, 2021 Hi Ian, yes, it is easy to reset the zero. WARNING - it is not the small screw on the rear face - that adjusts the bearing end float. Take the ammeter out of the car and bend the small tabs to separate the bezel from the can. Carefully remove the bezel, glass and face. Hold the magnet that passes through the coil and very gently bend the needle. It will require very little effort to correct the offset. Reinstall the face being careful not to bend the needle. Check it is now reads zero when in the correct attitude. If OK then put it all back together in reverse order. It is a very simple instrument. Mick Quote Link to post Share on other sites
Lebro Posted February 2, 2021 Report Share Posted February 2, 2021 +1 agree Bob. Quote Link to post Share on other sites
Ian Vincent Posted February 2, 2021 Author Report Share Posted February 2, 2021 Thank you all. Rgds Ian Quote Link to post Share on other sites
Lebro Posted February 2, 2021 Report Share Posted February 2, 2021 The capillary temperature gauge can be calibrated in the same way, stick the sensor in a jug of water, at say 185°F (using a known good thermometer) tweak the needle till it is on 185 - job done. Bob. Quote Link to post Share on other sites
peejay4A Posted February 2, 2021 Report Share Posted February 2, 2021 Alternatively and avoiding removing the ammeter from the dash, get yourself a small neodymium magnet and attach it to the back of the instrument panel near the meter. Move it around until the needle is centred. Get a cup of tea. It's not guaranteed to work but it did for me on my TR6. Quote Link to post Share on other sites
Ian Vincent Posted February 6, 2021 Author Report Share Posted February 6, 2021 So I went with Peejay's suggestion and ordered a pack of neodymium magnets on ebay (cost £3.99 for 10 inc. postage). My wife pinched 4 to use as super strong fridge magnets and I stuck one on the back of the dash panel as suggested. The trickiest part of the exercise was removing it after I started with it on the wrong side - they are definitely very strong little magnets, but once I moved it across to the coreect side, 5 minutes and job done. I then checked that everything still functioned when I turned the ignition on - which it did. Result! Thanks Peejay Rgds Ian Quote Link to post Share on other sites
peejay4A Posted February 6, 2021 Report Share Posted February 6, 2021 Glad it worked out for you Ian. Quote Link to post Share on other sites
JohnC Posted February 8, 2021 Report Share Posted February 8, 2021 And the great thing is that you can easily re-calibrate it if you move the car to the southern hemisphere. Magnetic dip is different here. Quote Link to post Share on other sites
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