GPS Speedometer

[1owner69Elan]

1owner, unfortunately those details I don't know. I simply brought *a* speedometer that has the same
input size as the one installed and the Speedbox to a local speedometer repair place with the required
speedometer cable length I needed and told them to make a cable to fit. As I recall, whatever size that
was required for the speedo end, also fit the Speedbox end. They, of course, also fit the necessary
nuts for tightening the sheath to their respective ends,ie, speedo and Speedbox. Nothing was out of the ordinary.

So, I have ordered the Speedhut Speedbox unit without cable. Speedhut confirmed that all that was needed for their unit to work in the Elan was a custom cable.

Custom cable ordered from Vintage British Cables (http://www.vintagebritishcables.com) as follows:

End 1: into the SpeedBox. 7/8"x18 female nut with 0.105 square end on the cable. This is standard American Ford specs.

End 2: into the original Smiths mechanical speedometer. 12mm nut with 0.125 square end. This is standard specs for the Smiths gauge in the Elan.

Note: the different size square ends.

Length: to suit. In my case I specified 35". I am placing the unit (as with previous unit) just under the bonnet skid plate on the left side (LHD car). Completely hidden and just wedges in. The new unit is even smaller than the old one. Also seems to have a faster sampling rate (10 Hz vs 5 Hz) and purported to be quieter, although I can't hear anything above the engine noise anyway.

Vintage British Cables (no affiliation) uses original Smiths tooling and IMHO provide the most robust and authentic cables. As well as accommodating custom needs as in this case. Turnaround, 2 days from order.

[gjz30075]

Thanks for the details.

[My72Sprint]

I converted to a Smiths Elan MK2 Electronic Speedometer Blue Warning Light (S4 Sprint) from Caerbont Automotive Instruments Ltd. They list Orange & Green Warning only now.
Differences: The display has a digital odometer but zero cables.

https://www.smiths-instruments.co.uk/lotus/elan
Tim

[1owner69Elan]

I converted to a Smiths Elan MK2 Electronic Speedometer Blue Warning Light (S4 Sprint) from Caerbont Automotive Instruments Ltd. They list Orange & Green Warning only now.
Differences: The display has a digital odometer but zero cables.

https://www.smiths-instruments.co.uk/lotus/elan
Tim

Using the modern Smiths GPS version is probably the most sensible approach if you don't want complexity and future problems. But, I really wanted to maintain the originality of the existing 52 year old speedo. If the GPS motor driven mechanical cable approach doesn't work or continues to cause issues I'll have to consider the modern GPS gauge.

Besides, the digital odometer and no separate trip odometer, it appears that the modern gauges (including repro mechanical ones) do not have the raised circular center of the original but rather a flat face (but the photos on the website don't make that entirely clear). Also the repro mechanical gauge odometer number fonts are quite different from the original. And spacing for MPH and placement of "Smiths" are different. Perhaps not of import except for us (sometimes) purists.

Heres what the three different faces look like:

Modern Electronic GPS:

Original Mechanical:

Repro Mechanical:

BTW, I note that the directional indicator light on my original speedo is green (not blue). Blue on the tach for high beams. Red on the tach for ignition.

[My72Sprint]

My Speed/Tac reversed from yours. Blue for high beams, Red on the tach for ignition.

GPS Speed reading an exact match with the reading from public speed gauges. The odometer show is good too.
Noticed the loss of GPS signal only once: Taylor road tunnel under the railroad, Newcastle California.
Tim

[1owner69Elan]

My Speed/Tac reversed from yours. Blue for high beams, Red on the tach for ignition.

Tim

Confused by this statement. I too have blue for high beams and red for ignition. So not reversed as you say. Both lights on the tach. Unless your blue light is not on the tach?

What I have:

Speedo: Green directional indicator
Tach: Blue high beams / Red ignition

You earlier indicated that you had a blue light on the speedo (no longer listed by Caerbont). Is that for high beams as you stated? The speedo has directional arrows on the indicator light, so would not make sense to have the high beam indicator there.

I have only seen green and orange lights for the directional indicator, and as currently offered by Caerbont.

[My72Sprint]

Checked just now...
Speedo: Green directional indicator
Tach: Blue high beams / Red ignition

[1owner69Elan]

Finally had the opportunity to install the Speedhut Speedbox. It went into the same location under the left bonnet skid as my (broken) Classic Speed. The cable mentioned before worked perfectly in adapting the Speedbox to the Smiths mechanical speedo. Only thing is I should have ordered the cable probably 2" shorter. It would have fit better in the space. I had to slide the unit toward the front of the car to keep the cable relatively straight to the speedo.

The Speedbox as delivered was reading about 10% too high across all speeds. I used the calibration cable and adjusted it according to the instructions. Now reads correctly as verified by a cell phone GPS speedometer and verifying speeds against the tach rpms. (I have a chart for speed vs rpm in all gears for my specific configuration of tires, gear ratios, and diff ratio.) Interesting to see the difference between the cell phone speedo and the Speedbox in terms of response. At steady state the two are aligned. But the Speedbox reacts much quicker to speed changes. 10 hz vs 1 hz refresh rate.

As a bonus, I had recently had the original Smiths speedo rebuilt as the internals had failed. Now, for the first time in decades I have a steady speedo needle. And accurate as well.

[phil1800]

Has anybody on this Forum actually bought one of the Smiths electronic Speedometers? I am trying for a couple of weeks now to get a response from Smiths/ Caerbont about a km/h version, but more so where I can buy one of these, even in mp/h guise.
None of the dealers listed on their website has them on stock.
Any help is appreciated!!

Thanks

Philipp

[1owner69Elan]

Has anybody on this Forum actually bought one of the Smiths electronic Speedometers? I am trying for a couple of weeks now to get a response from Smiths/ Caerbont about a km/h version, but more so where I can buy one of these, even in mp/h guise.
None of the dealers listed on their website has them on stock.
Any help is appreciated!!

Thanks

Philipp

Have you tried phoning them? Ask for Neil Meakin.

Emails largely go unanswered in my experience.

[phil1800]

I haven’t, but will do.
My issue is that the Lotus 5 speed in my S3 makes it impossible to access the angle drive withe the gearbox in place. I removed the rear gearbox support and rubber. Tiled the engine until the oilpan was against the frame. I could reach the angle drive with a finger, but no more. I can’t manage to remove engine/ gearbox on my own resources, thus I am looking for a lasting solution. Thank for the name! I will report on progress.

Philipp

[phil1800]

I have now ordered an electronic ‚Smiths‘ speedometer with Caerbont. Unfortunately, they initially confirmed to build the speedo with a km/h facia, only to withdraw later on. Delivery will take at least 8 weeks and I need to have a km/h facia printed once I receive the unit. A speedo shop close to Cologne is able to print these at reasonable cost. I won‘t use GPS, but an electronic pickup, as a GPS speedo signal is not legal here.
Philipp

[Frogelan]

Philipp

Just to jump in to the thread at this late stage, I'm a little surprised that Caerbont have declined doing a kmh version...I bought one about 3 years ago and they were happy to calibrate the scale to my request (at extra cost).

There do seem to be a few problems getting things done quickly in GB at the moment, I suppose this is a Covid issue.

[phil1800]

As said, they agreed, but then refused. The km facia will be €100- 150, which is silly, as they print the facia as Caerbont does.,,,

[Jayson42]

Has anyone tried the Dakata Digital GPS to mechanical unit?
https://www.dakotadigital.com/index.cfm ... &mode=prod

They standard have 4 output cables. I assume they won't fit the Smiths speedo? Need to get a custom cable from
http://www.vintagebritishcables.com?