52mm Fuel Gauge

[111Robin]

Has anyone fitted a separate fuel gauge with any success ?. Just wondering about calibration issues. It's my 1989 car with the printed circuit instrument cluster so I'm not sure if the voltage stabiliser is the same as the earlier cars.

[dklawson]

The 52mm Smiths gauges fall into two groups main groups, those that do not use the voltage stabilizer (used until the early 1960s) and those that require the stabilizer (from the early 1960s onward).

If you have a late model Mini and want to use a 52mm fuel gauge you will need to find a later fuel gauge (wide needle that does not bounce around wildly when you handle the gauge) and an external voltage stabilizer.

The later Nippon-Seiki gauges had the voltage stabilizer built into one of the gauges in the dash cluster. That's why I suggest you add a separate, external, solid state voltage stabilzer.

As long as you use the later model round fuel gauge (say from an MG or Triumph) it will work with the sending unit used in the later Minis.

[111Robin]

Thanks Doug. I'd be buying a new gauge so presumably that's all I need, just connect the wires as fitted to the current gauge ?. Will there be any calibration issues with the sender ?.

https://www.ebay.co.uk/i/273599569916?c ... J_EALw_wcB

[dklawson]

I am sorry, I made an incorrect assumption about your plans. When you said you wanted to use a 52mm gauge I assumed you meant a Smiths gauge. It never occurred to me that you meant an aftermarket brand like TIM.

Generally, aftermarket gauges already have a built-in voltage stabilizer which simplifies their installation. They just need a switched 12V supply, an earth connection, and a wire connection to the sending unit. Of course, the illumination lamp needs its own connections as well. However, there is a major complication.

Mk2 and later Minis use a sending unit that operate in a NOMINAL range of 270 Ohms = Empty to 30 Ohms = Full. The listing for the TIM gauge you are looking at makes no mention of what resistance range sender it works with. There are SEVERAL possibilities and NONE perfectly match the Mini. There is an industry standard sender that operates from about 240 Ohms = Empty to 33 Ohms = Full. That's close. If that's the sender the TIM gauge expects, you could use the TIM gauge with a Smiths sender... the gauge would however show Empty before the tank is really empty. That's not necessarily a bad thing.

Because of all the possible mismatches I would NOT buy the TIM gauge until you know what resistance range sender it needs.

That said, if you are OK spending another 40 or 50 GBP on the installation, you could buy just about any aftermarket fuel gauge you want and install it along with the Gauge Wizard from Spiyda Design. The Gauge Wizard is designed to match senders and gauges that are otherwise incompatible . That's the only way you will have an accurate aftermarket gauge with the Smiths sending unit.

[111Robin]

Thanks again Doug. I already have Tim water and oil gauges in the car, it was a John Cooper kit supplied with a walnut dash in the early 90s so I want to replace the clock with the fuel gauge and have a matching set. I'll check out the device you mention, sounds like the best option.

[Time Bandit]

I installed a seperate Smiths 52mm fuel gauge in my old MK1 back in the '80s. Memory is a bit vague now as it was long ago but I seem to recall in the instruction that I had that I needed a matching sender unit (or at least I think it was something like that, might of been the float arm that needed altered?), hower I just connected it up to the sender that was already in the tank without doing anything and it seemed to work fine.

[111Robin]

It's probably worth trying the new gauge first to see how it reads then. It has to be better than the existing gauge, I'm getting older and my eyesight is straining to see the miniscule gauge on the small cluster.

[111Robin]

According to the gauge manufacturer it is rated as follows :
Empty 240 to 260 0hms Half Full 97 to 107 Ohms Full 28 to 33.5 Ohms.

[dklawson]

According to the gauge manufacturer it is rated as follows :
Empty 240 to 260 0hms Half Full 97 to 107 Ohms Full 28 to 33.5 Ohms.

OK then. That's the 240 = empty to 33 Ohms = full standard I mentioned earlier.

That means you can use the Smiths sending unit with the TIM gauge. As I mentioned earlier, that means the gauge will indicate empty before the tank really is empty.

You could pump the tank dry, fit the sender and pour in one gallon at a time to determine how many gallons you have left when the TIM gauge starts to just climb above "E". Then you would know how much gas is left as your "reserve".

If you really want "E" to mean empty you will need to invest in the Spiyda Design Gauge Wizard that I mentioned earlier.

[111Robin]

Thanks Doug, I'm draining the tank anyway so will be able to check how much it takes to move the needle off empty.

[111Robin]

One more question, the gauge instructions show a 12v switched supply. Do i use the existing supply from the voltage stabiliser or just take a supply from the ignition switch ?.

[dklawson]

Do not use the output of the stabilizer to power your new TIM gauge. Use a switched, fused, 12V supply.

Dark green wires behind the dash are fused and switched.

[111Robin]

Thanks Doug, i figured this would be the case as the stabiliser output is 10v, but knew you would confirm so thanks for that.

[dklawson]

Thanks Doug, i figured this would be the case as the stabiliser output is 10v, but knew you would confirm so thanks for that.

Not only is it 10V, the output of the electromechanical voltage stabilizer is pulsed on and off between 0V and charging system voltage.