7 replies to this topic

[b80ven]

hi all,
The gauges in my mini are all getting old and are reading inaccurate readings (particularly the tacho which doesn't stop bouncing thanks to a worn out spring or two?). I want to replace the tacho and speedo and may as well replace the fuel / temperature gauges while I'm at it. Does anybody know if the new smiths gauges can be used as a simple replacement ?

Fuel gauge: I know the new fuel gauges specify which sender unit they pair up with so I should be able to find a match with my sender unit.
Tacho: I know these work off the square wave impulses which the ignition coil receives from the distributor but are there any calibration issues ?
Speedo: Does smiths make a speedo with the same connection as the original Minis had ?


Any information would be appreciated.


B

[Bungle]

try these guys for advice

http://www.gaugeguys...ths/classic.htm

[b80ven]

Hi all,

I have been having issues with my gauges on my 77 Clubman like the needle on the tacho bouncing around and the speedo getting stuck. I want to replace all the gauges and would like to hear from people who have done this. I have seen many custom dashes with all new gauges. Can new Smiths gauges fit straight on without any complications ?

Fuel gauge: I understand fuel gauges are paired with their corresponding sender unit so I should be able to find the right gauge for my sender unit.

Tacho: I understand the tacho works from the frequency of square-wave pulses received from the ignition coil, are there any calibration issues or is it a straight install ?

Speedo: Connections to the back of the new Smith's gauges, is it the same as the original connection with a female thread which can be screwed on by hand ?

Water temperature gauge: Again, are there calibration issues ?

Any information or suggestions would be greatly appreciated.

Hurc

[dklawson]

I will address as many of your questions as possible, but I am unclear whether you are swapping Mini gauges for Mini gauges or considering aftermarket equipment.

Fuel gauge: The Smiths sending unit (after 1964) operated with a resistance range of ABOUT 270 Ohms = Empty to 30 Ohms = Full. That's all "relative". A common industrial standard used by aftermarket gauge makers is 240 Ohms = Empty to 33 Ohms = Full. The Smiths sending unit will work with those aftermarket gauges but the gauge will show "empty" a little bit early. That's not really a problem, consider it an early warning gauge.

Tacho: You are describing a modern tach that uses a single sense wire connection to the coil (-) terminal. In general, any tach of that type (Smiths or otherwise) will work with the ignition in your car. If the gauge is in good condition there is no need/worry about calibration. Keep in mind that a few tachs were made exclusively for 4-cylinder, 6-cylinder, or 8-cylinder engines. Most aftermarket gauges are switch-selectable for the number of cylinders.

Speedo: This one will be your most challenging. Somewhere on the face of your olde gauge you are likely to find a 4-digit number. This is not a model number it is the "Turns Per Mile" (TPM) number. That number indicates the number of cable revolutions required to move the odometer up one mile. It also means if the input cable is turning in RPM what the gauge is calibrated for in TPM.. the gauge should display 60 Miles/Hour. Unless you want to spend lots of money addressing this, find a speedometer with the same TPM number as the one you are removing. Others will post about changing drive gears in the gearbox. I can mention buying a ratio box to mount in the speedo cable. Both work but both mean more money and time.

Water temperature gauge: Here again is a potential problem. My advice is whatever gauge you install, get a NEW sending unit matched specifically to it. Most aftermarket gauges will come with a matching sending unit. The only trick here will be getting an adapter to fit the aftermarket sending unit. If instead you are fitting a replacement Smiths temp gauge, be sure to know WHAT the gauge was used on originally and buy a matching sending unit for it. There are a couple of different sending units for Smiths gauges and I have yet to see a table that says "use ths sender with this gauge"..

[b80ven]

Thanks Doug.
Yes, my intention was to replace all of my old Mini gauges with new Mini gauges, not aftermarket ones but Smiths gauges.

With my speedo, there are two 4 digit numbers, one is 'AYG', the other is 'RPML'. From what you're saying, one of them must be the reading for the kms counter, the other must be for the speedo.

Regarding the water temperature guage, by sending unit, do you mean the actual sensor which bolts onto the engine ? I need to make sure the threads are identical which I'm presuming they would be with new sensors ?

[dklawson]

When I said 4-digit number, I did mean "number". For example a car with 10" tires and a 3.44:1 final drive would have the numbers "1280" on the gauge face. Take a look again and see if you can't find them. However, since your car is later than mine with the cluster gauges, this number may be hidden somewhere else. Hopefully others can tell you where to look if it is not on the gauge face.

I use the term sensor and sending unit interchangeably. I don't know of any sending unit that bolts to the engine. The temperature sending unit should be in a hole just below the thermostat housing on the front side of the cylinder head. The tap in the head will be 5/8 UNF (5/8-18). If you buy an electric gauge, its sender should thread right into that hole. If you buy a mechanical temp gauge with a capillary tube, you MAY need to buy an adapter that really just spaces the sending unit "out" further from the head. On some castings the expansion bulb of the sending unit is too long/deep and bottoms out inside the head casting without the adapter. (See Mini Spares part TE5 ).

[b80ven]

Doug,
Thanks for your prompt responses.
The two four digit numbers I noticed were "AYG - 1344" and "RPML 9453". THere is also an M-series number "M1410203". I tried googling these numbers but no luck.
THanks for the info.

ps, if any moderators are reading, I accidentally posted this thread twice, please remove one and have the responses included in just one of them if possible...

[dklawson]

The topics are merged.