10 replies to this topic

[Dartmoor Paul]

I've recently fitted a second-hand period Smiths temperature gauge into my 1975 Mini.  The Mini has a centre binnacle with a voltage stabiliser unit.  I don't know the history of the gauge but from reading a forum thread from January 2010 I wonder whether it is a pre-1965 gauge and therefore doesn't use the voltage stabiliser.  The fuel gauge is working perfectly.

 

I currently have a standard GTC101 sender unit fitted which I've checked using a multimeter and a beaker of hot water.  The resistance of the sender unit changes with temperature so I believe that it is working, and the sender unit has not been fitted using PTFE tape.  I've currently connected the gauge to the I terminal on the voltage stabiliser and it is earthed effectively (the illumination light works which uses the same earth).  When I switch on the ignition the needle moves up instantly to the "Cold" position where is flickers occasionally.  However the needle does not move up from there when the engine is run up to temperature.  When I short out the lead from the sender unit the needle immediately goes to "Hot" so I believe that the wiring is correct.

 

I now wonder whether if it is a pre 1965 gauge, I need to wire it directly into a 12V supply and use a GTC104 sender unit.  I've attached a photo of the gauge.  Can anybody help me please?

 

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[nzmember]

With 'made in UK' most likely post 64.  There is a part number under the face by the H which will tell you when the gauge was from.  Check the Somerford site.

Also, if it has one threaded screw on the back it points to be post 64.

[dklawson]

A picture of the back would be most helpful.

 

As NZMember said, there are some differences on the back of the pre-1964 gauges.  Specifically, in addition to the male spade lugs for wire connections there will be a pair of slots with threaded studs and nuts passing through the back of an early gauge.  Later gauges do not have the additional threaded studs.

 

The picture links below may not work as they are to the MG Experience which requires membership to view images.  If the images don't work, try cutting and pasting the address directly in your browser.

 

Early gauge with additional studs on the back (used WITHOUT voltage stabilizer):

(Sorry... the owner has removed the spade lugs from the top posts... but you get the general idea).

http://www.mgexp.com...a_gas_gauge.JPG

 

 

Later gauge used with the voltage stabilizer:

http://www.chicagola...cs/f-gauge6.jpg

[Dartmoor Paul]

My gauge has the two male spade terminals that you describe together with two threaded studs for fitting the securing bracket.  These threaded studs are in line with the centre line of the gauge.  It doesn't look like the picture on the MG website though.  However it does sound more like a pre-65 model.  If needed, I'll remove the gauge from the car and take a photo of the back.

 

Many thanks

[Dartmoor Paul]

I've taken some photos of the back of the gauge now.

 

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[dklawson]

Yes, that is an early gauge that uses its own special sending unit and works without the voltage stabilizer.   The slot on the back with the nuts on short studs identify it as a magnetic gauge as opposed to the later bimetallic gauge.

[Dartmoor Paul]

That's really useful ... thank you.  I take it that the correct temperature sender unit is part No. GTR102 also referred to as 52700.  Is that correct?

[dklawson]

I cannot tell you the correct sending unit for that gauge.  Though my car would have left the factory with a temperature gauge like that... it did not have one when I got the car as a project.  I have never tried to determine what sending units go with any of the temperature gauges (pre-1964 or after).

[Dartmoor Paul]

I quite understand.  One final question though ... is there any scope for calibrating this gauge if required and if so how?

[dklawson]

You can calibrate the early fuel gauge to work with its sender... I don't know if the same applies to the temperature gauge.  I could elaborate if you want.  Suffice it to say that the the temperature sending units that work with the voltage stabilizer are probably too different to work with the early temperature gauge.

 

You said your car is a '75 so it will have the voltage stabilizer.  it will be a lot easier to buy and install the later temperature gauge and later sending unit.  The early electric temperature gauges are not common so I am sure you could easily sell this gauge and use the money to buy a matching later gauge and sender.

[Dartmoor Paul]

Thanks for all of your help .You're a wealth of knowledge!