dunno - just something simple to flick the gear every 10th of a mile...



not hard once you've got the microprocessor and electronics set up

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did I tell you that I won a trophy?

I can't see a way to drive the original odometer easily, maybe someone with better engineering/modelling skills than I could hook up a stepper motor with a worm drive to turn the original drive part of it. Fundamentally I reckon the odometers are crap, that little lever that pulls the wheels around with each rotation...

My plan is to use a salvaged floppy drive stepper motor. These things are tiny, maybe 10mm in diameter. Apparently they have something like 200 or 400 steps per rotation, which should be perfect. The torque required to rotate the needle ought to be minimal so I'm hoping to do it without gears. they come with a sort of worm drive/leadscrew built in to their shaft so there are possibilities for using that to gear the needle too.

Regarding Harley's question about taking inputs and feeding them into a computer, its pretty easy really. The computer you uses is just a microcontroller, like a Pic or similar. I'll use a picaxe because I've used them before, but the oopic is really easy to use and has a built in stepper motor driver. They usually all have analogue to digital converters built in, so you take the signal (which is usually just a voltage ranging between a nominal 12V and 0) and feed it in, it then converts it to a digital value, usually ranging between 255 and 0. You can do some maths on it to calibrate it, then output it in various ways. Most microcontrollers can output PWM (pulsed width modulation) which is ideal for driving electrical gauges, and pretty much all of them will drive an LCD display.

I know stuff-all about electronics really, but by googling you can learn a lot.

Tim

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1951 Morris Commercial J Type Van
1955 BSA C11G
1961 Morris Mini Traveller
1969 Triumph TR6R
1977 Leyland Moke Californian

what about using some modern instruments and using the internals? i know that Rover used a fully stepperdriven speedo with mechanical odometer. later they replaced the mechanical odometer with a LCD.
as nearly noone likes Rover over here they are quite cheap.
look for Rover 200 instruments from 1995 on, like this
http://cgi.ebay.de/Rover-200-Bj-1998-Ko ... 286.c0.m14

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Rover 214 atm ....

This is a typical example of a stepper motor found in a modern gauge cluster.
The unit itself isn't so much a stepper motor, it's more like a clock in its construction.
The circuit / computer calculates what it wants to display and sends a pulse to the motor to make it move a given rotaion angle. No windings or anything, it's simply a donut shaped magnet on a pin running in a tiny gearbox.

I'd be quite happy to use something like this:

http://cgi.ebay.com.au/48-mm-mini-2into-1-ca-speedo-with-electronic-trip-meter_W0QQitemZ300349733845QQcmdZViewItemQQptZAU_Motorcycle_Parts_Accessories?hash=item45ee3d3bd5&_trksid=p3286.c0.m14

Provided it was a bit bigger and there was a away of calibrating it accurately.

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

Interested to see how well yours works Simon (as in longevity). If it lasts, it's a very neat solution.

From digging around on the UK sites, aparently the MG Rover sensor(anything from an R65 gearbox) has the right drive. Just not sure if the retaining nut is the same thread. e.g.
http://cgi.ebay.co.uk/MG-TF-MGTF-MGF-Electronic-Speedo-Speedometer_W0QQitemZ370219138698QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item5632c7be8a&_trksid=p3286.c0.m14

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Too many cars, and too little time.

the MGF did not use the R65 but the PG1 gearbox

Rovers from around 1996 should have this kind of sensor due to the electronic instruments. if i don't forget it i can check the thread later, i have such part somewhere.
its made by VDO by the way and not very small

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Rover 214 atm ....

That's right Only the 1.6l had the R65 'box, anything bigger had to have the stronger PG unit.

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Too many cars, and too little time.

Hi,

How is this project going Harley?

Has anyone yet found a speed sensor/sender that fits the Mini gearbox OR speedo end of the cable?

Cheers,

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

I was about to revive this thread myself.

I haven't done anything yet. I got some spare gearbox speedo drive bits with the intention of fitting a sensor to it, but have since changed my mind about that.
I'm going to run a standard cable now so will be looking for a sensor or looking to make / modify one to suit the end of the cable.

This means if I have any problems with it, I don't have to crawl under the car to fix it, and I can keep the sensor nice and close to my speedo in the dash.

Notice in my post above I mentioned the speedo end of the cable? Great minds think alike!

I'd rather fix something in the dash than on a driveshaft, or in a dusty rear hub, or in a muddy, oily and inacessable spot on the gearbox. But if there is an option that fits the gearbox easily I will consider it.

If we can find out the thread we can probably find a sensor that fits. There are a billion different sensors on eBay.

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

I've been tinkering in the shed for a while. I reckon I can make something fit something easy enough.

Regarding threads, the gearbox takeoff is M19 x 1.0p. That's a funny size, but on an early mini (850 / deluxe, anything before clip on speedo cables) speedo cable (speedo end) the thread is M12 x 1.0p.

The male part of a clip on speedo (the ones I have anyway) is 16mm diameter.

So, from that info, I'm going to try and find an M12 pickup sensor. If it doesn't fit onto the old mini speedo cable, I'll make an adapter to convert it to take a clip on unit.

i have a electronic VDO speedo gauge in my mini atm,
it has a auto calibration feature. all you need to do is drive a known Km and it sets the rest up for you.

the pick up is the original speedo cable mount (so the same thread is used) and the cable to electric sensor is glue to the out side of that. sends a voltage to the gauge and presto, no need for the speedo cable. much easier than manufacturing or building a speedo to suit.

Either works for me Harley.

I've seen M12 sensors, but they were all female thread. We need a male thread if possible. Or some sort of gender bender with a shaft.

The clip-on type might be easier. Find a 16mm diameter sensor and machine a groove in it to take the clip. Or bust up an old clubby speedo for the shaft and clip section where the cable outer fits.

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Brett Nicholson
Greendale (near Ballan) VIC.
1971 Morris Mini Moke
1966 Austin Mini
1965 Morris Mini Traveller
1973 LR Series 3 88
2007 LR Freelander 2

I was thinking of this:

http://s3performance.com.au/acewell-s2-hall-sensor-cable-p-2774.html?osCsid=jnfh6t1cjvru8i15i11fr1emq3

If that's the same thread as a mini speedo it means you could put it between the speedo and cable and use the sensor to drive an auxiliary function like a trip computer or cruise control setup.