TR6 Temperature Gauge Calibration Recently I decided to calibrate the temp gauge on my 1976 TR6. Ever since I can remember the gauge showed "normal" as just slightly over 1/4 on the gauge. For some reason I thought this might be low but in any event I was curious as to what temp was actually indicated by the gauge at its various positions. (The TR6 has a gauge which only has five marks (0, 1/4, 1/2, 3/4, and 4/4 but no indication of what the temp really is). I obtained a brand new sending unit from TRF (TRF part # GTR110, it is an Intermotor brand, my original one is a Smith’s). I immersed the measuring end of the new sender in a pot of water on the stove to observe various temp vs resistance values as the water heats up. I think many Triumphs use the same senders (at least TR5-8, Spits and GT6s). Here is what I found (using a thermometer calibrated in degrees Celsius). res (ohms) deg C deg F 500 42.0 107.6 450 46.0 114.8 350 49.0 120.2 250 55.0 131.0 200 61.0 141.8 150 70.0 158.0 100 92.0 197.6 Then my multi-meter started going funny. I thought it might be from the leads getting hot from being in contact with the hot sending unit. So I measured (with different leads) as the water was cooling: res (ohms) deg C deg F 70 78.0 172.4 100 68.0 154.4 125 60.0 140.0 150 52.0 125.6 180 50.0 122.0 380 48.0 118.4 Here is a graph of the results: I live at about 2000' above sea level so the boiling point is lower than 212 F (100 C). With the ignition switch in the on position (engine not running) I attached the following resistors between the new sending unit and ground and observed the following on my temp gauge (so the voltage regulator should be doing its thing on this circuit): res (ohms) gauge reading 200 half way between 0 and 1/4 100 between the 1/4 and 1/2 mark (closer to the 1/2) 50 3/4 exactly In conclusion, with the new sender the temp gauge now reads a needle width less than 1/2 when at normal operating temperature (using a summer rated thermostat - 160 F).