1. Does the Smiths 52mm fuel gauge work with the standard Mini fuel tank and transmitter and is it accurate?

2. If I piggy-back a Smiths water temp gauge on to the same sensor as the original water temp gauge will they both read correctly or will they be screwed up due to having to share the same variable earth point, if you see what I mean? The reason I want to do this is because I prefer the more detailed info from the Smiths gauge but at he same time I don't want the original in the Metro instrument housing doing nothing and looking as if it's broken.
Come to think of it, will the same principle apply to the fuel gauges?

1. No idea

2. My first thought is that if you put two gauges in parallel connected to a single sender only half of the current will flow through each gauge and, since they work on a heating coil/bi-metal strip arrangement they will both read low.

Smiths fuel and temperature gauges are also designed to work with a voltage stabiliser unit which 'stabilises' the supply at around 10v.

http://merlinmotorsport.co.uk/product_i ... m=Shopping

It's all about impedance (resistance). If the dials are high impedance, then they will have little effect on each other, but as they are low tech, I would imagine that they are lowish impedance and therefore, each gauge will see the other as part of the load it is measuring.

The best way is to wire them up and see! How accurate is a temperature gauge and fuel gauge anyway? The shape of the tank has the biggest effect on linearity. I've had cars that can cover 100 miles before they even move off full, but can empty the bottom quarter in 25 miles!! You'll soon learn when they are either hot/ cold or full/empty!!

1. There are different SMITHS 52mm fuel gauges and some will work but some won't. It's all down to whether the resistance range of the sender matches what the gauge is expecting to see. Outside of that you can add resistors in series and parallel to get it somewhere near if it's out and failing all else get it to read empty when it nearly is and you know anything else is "not empty". I know a few cars where anything over half a tank reads full and the gauge only actually reads the bottom half of the tank. Come to think of it my Volvo is like the case mentioned where if I brim the tank it'll do nearly 100 miles before the needle comes off the stop - it'll then do another 250 to the halfway mark and only 150 for the bottom half. I assume the gauge is reading a logarithmic scale whilst the printed scale is a linear one. The Mini I've just sold had a 52m Smiths gauge from a Scimitar (which did read correctly with the Mini sender) and the scale printed on the face was logarithmic so the halfway mark really was half a tank left but it wasn't halfway across the scale. Basically you get a more accurate reading as the fuel level gets lower.

2. Has been answered. If they interfere just stick resistor between the sender wire and earth on the Metro one to make the needle come off the stop and sit somewhere in the scale. Maybe a pot and you can play with it to suit your fancy.

Iain

Thanks for all that guys I thought that I'd ask the question(s) before buying the gauges so in the light of all the info above I'll go do some shopping and suck it and see. If they don't work at least I have some ways out to explore. Cheers