Unfortunately all older model instruments are not the same.... The older ones ..that use the voltage sensed fuel gauges ... also use a temperature gauge that runs at 12V. Slightly less older setups using the current based fuel gauge have a different temp gauge that also uses 10V. If you still have a voltage regulator attached to the back of the speedo then maybe you have the later setup.... or maybe not. (Its a absence is not confirmation that it shouldn’t be there :(

Because the type of fuel gauge you use is determined by the age of your fuel tank (the senders are not interchangeable - at least not without a LOT of trouble) a PO (moi??) may have mixed and matched 12V instruments and their 10V cousins.

Cheers, Ian

I couldn't find a fuel sender part# or description on MiniMania, but I did find this over on MiniSport (in the UK). My car was originally a '91 SPI so this unit should be the one fitted inside my fuel tank:

https://www.minisport.com/xnb10007-fuel-tank-sender-unit-1974-94.html

No technical details are on that page however - can someone tell whether or not this is a voltage-based or current-based sender unit? I also have a multimeter if someone can give me pointers on how I can use that tool to reverse-engineer the signal from the current sensor. EDIT: I know how to use an ohm-meter to actually visualize the resistance from the sender - I'm just not sure how to confirm that THAT signal will properly drive the gauge on the older-style Smith's fuel gauge. Sorry if I was unclear...   

I'll be attempting to hook up to the fuel gauge present in a older-model, black-faced Smith's speedo - unfortunately I have no data on what year or model Mini the center binnacle was sourced from (I got it at a swap meet and the seller didn't know). I can take pictures and/or inspect the unit itself looking for identifying marks and/or serial numbers however if anyone reading this is knowledgeable enough to interpret my data. 

Thanks!
  

It will be difficult to find someone whose done the conversion before because we don’t know exactly what conversion you’re contemplating. You should be able to find the output voltages from a “91 Sprite” temp sender reasonably easilly. However, you still need to identify your gauge and its specs (high/low reading voltages). Alternatively, once you find your gauge specs it should not be too hard to find a suitable sender.

Similarly with the speedo. It will more than likely not be a simple cable swap. Presumably (because its years since I looked at one) your Sprite speedo has its calibration (turns/mile (or km)) printed on its face. Your early speedo will have this info ... if they’re different then you will need new speedo gears (fitted to the gearbox) or a converter box. Early speedos can be adjusted without the need for replacement parts ..but the odometer will require new bits.

There are 2 types of early fuel gauge (one voltage sensing the other uses current) so once you work out which you have you can canvass for solutions.

Cheers, Ian

Ian,

I get *everything* you're saying here, which is why I asked. =)  I posted here because I was hoping that someone had successfully completed this modification using similar before/after hardware. I even asked MiniMania direct and they not only confirmed what you said re: the oil pressure sender (with a recommended part#), but finished with (emphasis mine):

"The original 2 inch gauges for oil pressure generally connected to the block with through a copper and rubber hose combination and read the pressure directly from the block: https://www.minimania.com/part/2A269/Classic-Mini-Adapter-Oil-Gauge-Pipe

The fuel gauge connected to the electrical lead from the sender - but yours is a much later sender than was used with the gauge either built into the Speedo or on a separate 2" gauge - so, I'm not sure  how well they'll work with a later fuel sending unit.

Likely you'll need to go to a shorter speedo cable.

Water temp can either be an old type capillary tube into the head or an electronic sensor type.

You might want to reach out on the forums and connect with someone who's done the conversion for advice."

So...

Sounds like I have a good lead on the oil pressure system to that gauge.

The water temp sensor is *electronic* not capilary tube - the question is will the old Smith's gauge read that signal - anyone know?

The fuel level sender is also an unknown - I suppose I can just hook it up and see if it reads correctly (if at all) - I don't think I'll damage anything with such a 'live fire' test... will I?

Plus I'll need a new speedo cable, which I was expecting.

Basically, Gauges 101 needs to know if you gauges are mechanical or electrical in order to provide assistance. Smiths make both types. Early Minis (when fitted with aux gauges at the factory) used a mechanical oil gauge and an electrical water gauge.

This means that the oil gauge needs a fitting that attaches to the block with a small outlet tube that fills with oil (and maybe a bit of air). The other end of the tube attaches to the gauge. Inside the gauge is a small bellows. As oil pressure in the block rises, the tube transmits this pressure to the gauge, which compresses the bellows and moves the needle.

The water temp gauge has a sender attached to the block. The sender translates water temperature into a voltage. The sender is attached to the water gauge by a wire that transmits this voltage to a sensor in the gauge that moves the needle. You will need to know what voltages you gauge needs for hot and cold and make sure the sensor provides the correct values....

You don’t need any specific loom; just the correct sensor (one that matches the gauges you have)and the correct transmission medium (electric wire or copper/rubber/nylon tube) and connect the two together....

If you don’t have the factory bits then you just need the sensor/connector that matches your gauges and join ’em up. (There are mechanical water gauges and electric oil gauges .....) ...And, no, the sender that lights the red oil light won’t provide the data that an electric gauge requires.

You may also need a diffferent speedo cable ..... and a speedo whose calibration matches the gearing fitted to your gearbox....

....And maybe some way or relocating the flasher indicators?? ..... and a different fuel gauge and sender???

Its not quite click and play..

Cheers, Ian

I did look - all it says is:

"This is the wiring short conversion loom that fits to the old central speedo and is used by people modifying from 2 or 3 clock dashes to single clock or just repairing damaged looms. With the correct bulb holders and spade fittings. Now uses 5x LLB987 and 2X GLB2132 bulbs."

The only details are about bulb holders and spade fittings - it has no details about what specific gauges (if any) the leads are designed to send signals to, nor does it give details (unless I missed it someplace) about things like whether or not the Oil Pressure sender I have on my car now (which registers as a basic red light on the square clocks) will properly register on the Smith's oil pressure gauge (which has a sweep needle). 

That's why I asked if anyone had successfully done the conversion.

I'll give the US supplier a call - hopefully they can tell me more about how the harness has actually been successfully implemented in cars using my before/after hardware.

Thanks! =)

Great find for the bulbs - thanks!

What about the gauges themselves? 

I have a '91 British Mini Sprite (right-hand drive w/ the square instrument cluster above the steering column) that I'd like to convert to the old-style center binnacle. I actually have the entire binnacle assembly thanks to a parts swap meet a few years ago which has:

- Center-mount speedo (black) w/ fuel gauge

- Oil pressure gauge (separate)

- Water temp gauge (separate)

- Ports for various lights/indicators but DOES NOT have the actual bulbs!

All the binnacle gauges are black Smith's units.

My car is currently running the more modern gauges in the square mount - there's a circuit board behind the gauges that carry power to the various gauges, wired into a central harness. My main question is: Can I re-wire the old Smith's gauges into the existing wiring, or are the signals from the various (more modern) gauges' sender units incompatible with the old gauges? Are there other complications I should be aware of? (For example, by car has a low-oil pressure *light* but not a fully-readable gauge). Thanks a million in advance!