28 replies to this topic

[Chas campen]

Hi , I would like to fit a temp gauge to my 89 City ... 998cc.

There looks to be a sender unit in the head with a spade electric terminal....

How do I go about fitting a temp gauge ? is it just a case of connecting one side of a gauge to the sender and the other side to a live feed ?

Thanks

[matt050990]

Pretty much. One side connected to the sender unit. The other to a 10v source from the back of the speedo unit (dependant on speedo type)

Fitted mine no more then 2 weeks ago :)

[dklawson]

To elaborate on the above,...

 

Whatever temperature gauge you are using needs to be compatible with the sending unit.  You cannot mix brands.  Assuming that the sending unit in your car's cylinder head is a Smiths part, it will be compatible with "a" Smiths gauge but not EVERY Smiths gauge.  There were several different gauges and sending units used over the years.  Therefore, since you don't appear to have a gauge at the moment, buy a matching gauge and sending unit so both are new and known to work together.

 

As stated by Matt, the Smiths gauges have to be supplied by 10V from the instrument cluster's voltage stabilizer.  If you don't want to do that, buy an aftermarket, solid-state 10V voltage stabilizer (eBay or Moss) and use it to supply the correct voltage to your Smiths gauge.  Do not run the gauge without the stabilizer.  The gauge expects 10V.  Without the stabilizer, the car's system voltage will supply the gauge with as much as 14.5V so the gauge will read high and have a reduced life.

 

If you decide on an aftermarket electrical gauge, those typically have a built-in voltage stabilizer so wiring them up is easy and does not require connection to the Smiths voltage stabilizer.  However, as I stated above, you need to match the sending unit and gauge.  So... your aftermarket gauge will come with its own sending unit and you will have to find an adapter to mount it in the cylinder head.

 

All that being said, if you don't have a temperature gauge at the moment, consider buying a mechanical one.  They require a bit more mechanical work to fit but you won't have to worry about electrical connections except for the illumination bulb. 

[Mk1cooper]

I've been reading a lot about the never ending temperature and fuel gauge issues with the voltage stabilizer. I have a 1963 Austin a Cooper with the center 100mph speedo gauge cluster that appears to be period correct but I can't seem to find a spot behind the gauge cluster where I can install a mini spares voltage stabilizer. I did all the checks and both gauges are working properly but when turned on even at full tank, my fuel will read half way and slowly will start from middle going down when my fuel starts to get low. The temp gauge moves few millimeters above the cold when ignition is switched on but stays there even when engine is hot.

Getting frustrated and I really don't want to buy a new gauge and sending unit as much as possible. Maybe there's an aftermarket stabilizer that I can buy and simply wire to those two wires to give them 10 volts?? Is there such thing?

[dklawson]

Your '63 will not have been designed to use the voltage stabilizer.  Don't plan on adding one as it will not benefit your gauge system.

 

The gauge system before 1965 is sometimes called a "moving iron" or "magnetic gauge" system.  There are several things that can "mess it up" but the voltage supply isn't typically one of them.  Unlike the later gauge system, it is imperative that the gauge have clean terminals and have a good earth connection through its mounting screws.  Likewise, the sending unit must have a good earth connection via its black wire.  Once you have addressed those points see how the gauge behaves.  If there is no improvement carry out the following two steps.

 

First, look through the filler neck of the gas tank using a flashlight.  Confirm that the float is on the top of the gasoline.  The early senders used a metal float soldered onto the float arm.  They don't fail as often as the later plastic senders but they can become perforated and fill partly with gasoline.  If there is any gas in them the float will not be on the surface and the gauge will read "low".  If this is what you find, you will probably need to find a donor float from another car and solder it onto the arm.  Early sending units are rare and expensive.

 

If the float is floating properly at the top, it may simply be that your gauge has lost its calibration.  I will not post the calibration procedure here.  Instead I will direct you to Barney Gaylord's MGA-Guru web site.  Read through his pages explaining how the gauge system works and then how to calibrate it.  Do not focus on the resistance values he uses for the MGA... calibrate your gauge to match your sending unit precisely instead.

 

Barney Gaylord's Pages on the Early Fuel Gauge

[Spider]

Hi , I would like to fit a temp gauge to my 89 City ... 998cc.

 

 

Forgive my ignorance, I am not up to speed with every aspect of these later models, however I would have felt reasonably sure that being an 89 model it would have been fitted with the '2' or '3 clock' instrument set up which incorporates a temp gauge?

 

Now I've while I've just written that, I jut recalled that I do happen to have a Feb / March 1988 sales brochure (book really) that covers all the (UK) Austin Rover cars that were on sale at that time and yes, in the specs for the Mini (there were 3 models available at that time), they all had Temp Gauges fitted.

 

<Edit:   3rd try!!!!!!!!!!     so has someone removed the factory fitted gauge?>

 

 

Yippppeeeeeeeeeeeeeee   worked that time :)

Edited by Moke Spider, 13 March 2015 - 02:37 AM.

[Mk1cooper]

Your '63 will not have been designed to use the voltage stabilizer.  Don't plan on adding one as it will not benefit your gauge system.
 
The gauge system before 1965 is sometimes called a "moving iron" or "magnetic gauge" system.  There are several things that can "mess it up" but the voltage supply isn't typically one of them.  Unlike the later gauge system, it is imperative that the gauge have clean terminals and have a good earth connection through its mounting screws.  Likewise, the sending unit must have a good earth connection via its black wire.  Once you have addressed those points see how the gauge behaves.  If there is no improvement carry out the following two steps.
 
First, look through the filler neck of the gas tank using a flashlight.  Confirm that the float is on the top of the gasoline.  The early senders used a metal float soldered onto the float arm.  They don't fail as often as the later plastic senders but they can become perforated and fill partly with gasoline.  If there is any gas in them the float will not be on the surface and the gauge will read "low".  If this is what you find, you will probably need to find a donor float from another car and solder it onto the arm.  Early sending units are rare and expensive.
 
If the float is floating properly at the top, it may simply be that your gauge has lost its calibration.  I will not post the calibration procedure here.  Instead I will direct you to Barney Gaylord's MGA-Guru web site.  Read through his pages explaining how the gauge system works and then how to calibrate it.  Do not focus on the resistance values he uses for the MGA... calibrate your gauge to match your sending unit precisely instead.
 
Barney Gaylord's Pages on the Early Fuel Gauge

I removed the fuel sending unit and it does have the metal float and I turned the ignition on and slowly tested the float by simulating full level by pushing the float up. The gauge reads half way and as I slowly move the float down, the reading goes down as well to empty. So my full tank reading is "half-full" on my gauge.

I pulled the temp gauge sending unit wire by grounding it when ignition is on and the reading says it's full hot. I'll look at the calibration page. Please let me know what other tests I can do. Thank you.

[dklawson]

Since you have tested the fuel sending unit out of the car and found that "full up" on the float arm only displays 1/2 full on the gauge, you have done all the testing that is required.  Clean all the electrical connections, ESPECIALLY the mounting area and screws for the fuel gauge.  If no improvement, refer to the calibration pages I provided the link to earlier.  Use your sending unit (not external resistors) during the calibration steps and you will have a perfectly matched gauge and sender.

[Mk1cooper]

Same with temp gauge? How do I calibrate the temp gauge?

[dklawson]

The temperature gauge may be a different issue.  There were some early electrical temperature gauges that worked without the voltage stabilizer.  While I have seen pictures of them, my car did not have one when purchased so I have not worked with them.  However, it is highly likely that over the years your car's temperature sending unit has been replaced by one that is not fully compatible with the gauge you have.  I'm sorry... I cannot tell you which sender would be correct.  However, you COULD through experimentation calibrate the temperature gauge the same way you calibrate the fuel gauge.  

 

Remove the temp sending unit, attach clip leads to it (one o the threads, one to the electrical spade lug.  Place the sending unit in boiling water with clip leads attached.  Measure and record the resistance value across the two clip leads.  With the same setup (wired sending unit in boiling water) place a thermometer in the pot and turn off the heat.  Allow the water to cool slowly as you monitor the temperature.  When the water reaches 185oF (85oC) measure and record the resistance.  Allow the water to cool further to 90oF (32oC) and again record the resistance value.  On a Smith C-N-H calibrated gauge, the 90oF resistance corresponds with about the middle of the "C" range.  The 185oF resistance should be the middle of the "N" range.  Finally, the resistance value you measured in the boiling water will be right at the START of the white band in the "H" range of the gauge.  Knowing those three resistance values you can buy discrete resistors of the correct ratings and carry out temperature gauge calibration as described on the MGA Guru web site.

 

However, my advice to you goes one step further.  If you are going to go to the trouble of calibrating the temperature gauge, buy a new temp sending unit and note in your logs exactly which one you selected.  That way you will be able to purchase a matching sending unit in the future and will not have to repeat the calibration process.

[Mk1cooper]

I'll figure out this weekend. Should be a fun weekend activity to do. But I'm not a collector and I do drive the mini to school everyday. So whatever works even non original parts is cool but I'm totally against installing something that isn't period correct. So I might consider looking for an early 60s Smiths/ Lucas/ Stewart Warner etc... to replace the non working gauges if I can't calibrate them.

[dklawson]

How original you keep the car is obviously up to you.  If you decide to change the gauges, you can fit different, Mini specific gauges from a Mk2 or later along with the corresponding "correct" temperature and fuel senders.  Unfortunately, the change does not stop there.  You will also need to add a voltage stabilizer to the system and change to the later LH gas tank with the bayonet mount sending unit.  

 

There is another option to you.  Contact Chris at Spiydadesign.com.  He has several "gauge wizard" products that allow mixing and matching different gauges and sending unit.  I believe you can also use his circuits to compensate for calibration errors.  A couple of his remotely mounted circuits may be able to address your gauge issues while retaining the original look of your car.

[Mk1cooper]

Thanks a lot Doug! Original is nice but the same time I like the Works austin cooper S rally dashboard and everything done to these race cars at stanceworks website so might go that route too. I'm gonna check out Chris! Stuff at that website. I'm curious what they got for the cooper.

[Mk1cooper]

Website doesn't work Doug

Spiydadesign.com

[Spider]

Website doesn't work Doug

Spiydadesign.com

 

Try this link

 

https://www.spiyda.c...lectronics.html