My electronic speedo install

[elcaminokid]

The speedo in my car wasn't working anymore, so instead of trying to find the unobtanium gearbox parts, I started to look for another option.

1st option was a GPS speedo. Cheap and cheerful, but:
   - Potentially no speed signal in tunels (there's not many where I'm at) but maybe more important;
   - GPS speedo doesn't seem to be legal and speedo needs to be hard wirded?

The Smiths electronic speedo's are very cool, but expensive.
I had a look around and settled with a marine/truck application from VDO (SingleViu).
This is an 80mm speedo with white needle, just size as the original Smiths the Europa's came with.

Here's how I did my install:
1st I had to determine where pick up the signal for the sensor.
I decided on the disc bolts for the hub (I ground them blank)


As you can see, the bolt from the steering arm to the hub was too short to add a bracket:

...so I picked up a longer one:


Fabbed a bracket for my sensor:



And then, put it all together:



Initially I was worried how to adjust the sensor within 1.0mm from the bolt heads, so I used a bigger sensor (M12) which allows a bigger gap (up to 2mm).
In the end it was super easy to meat with the fine thread on the sensor, so I could have used one size smaller sensor:


The wiring for the speedo was straight forward:
12V continuous
Ground for meter
Ground from meter to sensor
12V Ignition
Signal from sensor

The sensor wiring I did as follows:
Ground (the one coming from the speedo)
12V (I took from acc on)
Signal to meter

The prgramming of the meter was real easy. Just imput the amount of pulses per km and you're done.
I used a tape measure to measure 2 rev of the wheel (I think it was 320cm) = 8 pulses.
Pulses/km = (100000cm / 320cm) x 8 = 2500

Total cost:
The VDO meter was €95
The speed sensor €8 (I used  LJ12A3-4-Z/BX, NPN - NO)
Various pieces of wire, angle iron, bolt, etc +/- €20.
Very happy with the result. It all works perfect, but I will make a new beefier bracket in the future as on rough roads, the signal fluctuates a bit. On smooth roads, spot on (tried upto 120km/h).

[BDA]

Nice write up! Congratulations!

[dakazman]

What device  are you observing your vehicle speed on , the original speedometer?
  I enjoy reading how members  share how we come up with practical solutions.
Very nicely done!👍👍
Dakazman

[EuropaTC]

Another "well done". I like articles like this which show how we can adapt with modern ideas. Although the cable operated speedometer works well enough it does have a long cable run and I've had a few cables  go over the years so an electronic one looks good.

Question - does it work by sensing the bolt head, and if so, do you count 4 (bolt head) pulses as a complete revolution ?  Or is there another trick that I've not understood ?

Brian

[elcaminokid]

Nice write up! Congratulations!

Thanks!

What device  are you observing your vehicle speed on , the original speedometer?
  I enjoy reading how members  share how we come up with practical solutions.
Very nicely done!👍👍
Dakazman

The VDO SingleViu is the new Speedometer. I like it becasue VDO is a reputable brand, this range is quite cheap and, what I liked best: it has a toggle switch for the display on the speedo itself (to toggle trip, odo,...), which the cheap ebay speedo's usually don't have.

Another "well done". I like articles like this which show how we can adapt with modern ideas. Although the cable operated speedometer works well enough it does have a long cable run and I've had a few cables  go over the years so an electronic one looks good.

Question - does it work by sensing the bolt head, and if so, do you count 4 (bolt head) pulses as a complete revolution ?  Or is there another trick that I've not understood ?

Brian

Thank you.
You understood correclty. The speed sensor is basically a proximity sensor. When it senses metal it generates a pulse. So indeed, each revolution of the wheel is 4 pulses. The more pulses, the more accurate the speed reading, but I compared with GPS app on my phone, and it's spot on.
Aftermarket companies will sell you 'speed sensors' for anywhere between €35-80, but basically they will sell you an €8 proximity sensor with the type label removed 

[EuropaTC]

Aftermarket companies will sell you 'speed sensors' for anywhere between €35-80, but basically they will sell you an €8 proximity sensor with the type label removed 

Now that is something I would never have thought of and to an aging Luddite like myself it's almost in the "magic" class !

Thanks for that little snippet.

Brian

[dakazman]

Well said , Brian.
  I really need one of these in my ElCamino . It’s funny the el Camino kid posted it.
Original equipment can be had for $1800.00 some others $800.00 , used un -warranteed go for 200.00.
  I been waiting for a friend to send me several Rochester carbs from Rochester,  NY .  I can’t make this stuff up.
 It’s the final pieces needed for o get my 84 on the road.
Dakazman

[Gmg31]

I didn't realise that GPS speeds were illegal.  My Smith Speedo jammed so I fitted a GPS one.  Cheap and easy to install.  But on really cloudy days it doesn't work.  (which is regular thing in the North of England) 

[EuropaTC]

I had heard that GPS speedos weren't legal in the UK, probably because of the reasons you've cited.  I was surprised so spent a bit of time looking and found this

https://www.gov.uk/government/publications/individual-vehicle-approval-iva-for-cars-help-to-get-a-pass/individual-vehicle-approval-iva-for-cars-help-to-get-a-pass#speedometers

You'll have to scroll a long way down to the testing section but there's a sentence that says GPS aren't allowed. The page  is 2017 so unless something has recently changed I expect this is still the law. If it had I'd expect a gov.uk website to reflect it anyway.

In practice I reckon you'd get away with one at MoT time because unless the tester suddenly decides to do a road test they'll only drive it at 10mph into the MoT bay and not even register.  So as long as there's one fitted and it lights up (not lighting up is a fail !!) I think you'll be fine. Personally I'd fit a sensor driven one if I had to, I'm not sure how GPS works on steep hills - doesn't it work on longitudinal distance from space rather than actual distance the wheels turn ?

Brian