To convert you would need to buy or fabricate a conversion harness and all the parts associated with the center binnacle for the early gauges.  Very possible.  While I am sure that several people on this board have made the conversion, it is also very common in the U.K. and a fairly frequent topic on The Mini Forum in the U.K.  You might get more detailed answers and links for parts sources on that board. 

//www.theminiforum.co.uk/forums/

Regardless, to buy the correct center binnacle speedometer for your car you will need to determine what your car needs now so you buy a gauge with the proper calibration.  John at GuessWorks in the U.K. has a lot of information on his web site that will help you understand speedometer gearing.

//www.guess-works.com/

Hi, how easy would it be to get rid of my current 2 clock dials behind the steering wheel and wire up a smiths dial in the centre? is it a big job or can I do it in a couple of hours?

Also although I have a 1275 metro engine and my current speedo goes up to 110mph could I replace it with a smiths speedo that only goes up to 90mph. I would think that would be a problem as I won't go faster than 90mph in the car. I don't know, im just guessing.

thanks

It doesn't quite work that way.

The odometer is "geared".  It works with a worm, pinion, and pawl mechanism driven mechanically off the spinning cable.  If the odometer is working and reading correctly (you know you drove 50 miles and the odometer registers 50 miles) then you know your speedometer model is correct for the final drive and and tire size you are using.  This is frequently identified by the turns-per-mile (TPM)number on the face of the speedometer.  The TPM number identifies how many cable revolutions are required for the odometer to count/indicate 1 mile.

The speed indication portion of the speedometer is not geared.  It uses induction currents and magnets to move the needle.  A magnet assembly inside a shallow aluminum cup is spun by the cable.  The spindle the needle is attached to is attached to the aluminum cup and that is held against the zero stop by a hairspring.  When the magnet spins inside the aluminum cup it induces electrical currents that "couple" the two components driving the aluminum cup (and attached needle) against the return force of the hairspring.  If the spring is too strong or weak, if the needle bearing the spindle is supported in is dirty, or if the magnet assembly has the wrong strength (too strong or to weak), the speedometer portion can read incorrectly. 

The magnetic induction coupling used for speed indication allows for slippage and therefore speed indication can be (and often is) out of calibration while the geared odometer is accurate (or at least as accurate as a Smiths gauge can be).

Hen1275, in the U.K. contact Speedy Cables.  They are the most commonly referenced repair center for Smiths Gauges.  The behavior you are describing (particularly since the car sat for a couple of months over the winter) may simply be due to the speedometer portion of the gauge needing a good cleaning. 

However, if you have changed the tire size to 12" just before putting the car in storage then the tire size change may be creating the problem and you simply may have not noticed it prior to storing the car.  That is basically what DrMini is suggesting is wrong.  The odomter test will tell you if you have the wrong speedometer for your gearing and tire size.  Drive a know distance (several miles) and compare the known distance to what your odometer records.  That will tell you quickly if this is a gearing issue needing a different speedometer or calibration issue requiring cleaning and recalibration.

Hi, but the speedo was working fine a couple of months ago, then it wasn't used for a while then when we did use it that's when the problem emerged.

Also you mentioned two places to get the speedo looked at and they are both in America and I live in England and it would cost a lot to get it shipped over if its just a small problem.

thanks

I don't understand how the Odometer can be working correctly if the Speedometer is not working correctly?  If the Speedo registers 50mph when you are doing 65 to 70, then the odometer should be reflecting 50 miles of trave for every 65 to 70 miles you have travelled.  Does that make sense?  I would think that the speedometer and odometer are working correctly for the final drive you have if combined with the stock wheel and tire set up.  As you have gone to larger tires, you are covering more ground per tire rotation than you would have with the smaller tires.  Before you get the speedo re-worked, you probably need to provide the final drive ratio and wheel size to the instrument repairers.  JMHO. 

Yes, as Larry said, you can fix your current speedometer.  He gave you the names of two vendors who repair and calibrate gauges.  Two more are MoMa and APT (gaugeguys.com).  

As long as your odometer is working correctly and accurately it indicates that the gauge itself is correct for your car.  If that is true, all that is required is for the speedometer shop to clean and calibrate the gauge you have.

Hi, im not too keen on the sigma bike speedos as I want to keep my mini looking original and old school. So cant my current speedo be fixed so i can still use that or is the next option buying a new one?

thanks

We keep talking about Sigma because not all bike ones will adjust down to the smaller wheel sizes. I am sure any will work as long as it can be set-up for the wheel size you have.

The 3V coin cell batteries in Sigma bicycle computers last 2 to 3 years.  Buy one of the Sigma models with EEPROM memory so when the battery dies your presets are saved.  The Sigma speedo will be an accurate and inexpensive solution.  The image below is a Sigma BC1600L (with EEPROM) installed in my Mini.  

The only bad thing is there is no continuous backlight for night driving and you don't want to keep pushing the Sigma's lamp button as it runs the battery down faster.  I have an LED aimed down at mine for night driving.

//home.mindspring.com/~purlawson/pictures/gauges/Dash03.jpg

Hi, but would the bicycle speedo last long or would it only be a make shift job? Or would replacing the speedo be a more expensive but better solution?

thanks

The exact thing one I had did. The odo worked just fine though.

The cheap fix is to install a bicycle speedo from Sigma Sports. You should be able to pick one up for less than $20. You may have to add some wire to reach where you want it to fit. Glue a magnet on the output joint from the trans and adjust for your wheel size.

Its busted and needs to be repaired. Nisonger on East Coast or PaloAlto Gauges on West. Typically $200.

Hi, my speedo seems to work up until 30mph but after that it roughly goes up 3mph for every 5mph that you do. And the maximum that it then reads is 50mph, so when you are actually doing 65-70mph it is only reading 50mph. I know this as I've tested it on my sat-nav which is pretty accurate. I've read that if you have non-factory wheels this can affect the speedo, and I have 12 inch wheels on at the moment.

Any thoughts or Solutions??

thanks