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Sun Oct 14, 2018 4:47 pm

I have a Subaru swap and am considering switching to a GPS Speedo since mine is on the fritz and metric.

Does anyone know of a GPS Speedo that I can connect my VSS too?

Mon Oct 15, 2018 12:23 am

That’s is a strange question: a GPS speedo assumes no need for a vehicle speed sensor (VSS). You are not likely to find a gps speedo with a VSS input. What are you trying to accomplish?

Kourt

Mon Oct 15, 2018 1:22 pm

I have a Subaru swap. Don't I need a signal for the ECU?

Mon Oct 15, 2018 1:24 pm

Kourt, I believe he needs to supply a VSS signal to the ECU and is looking to see if there is a GPS based system that can do that.

Mon Oct 15, 2018 1:44 pm

A GPS works on radio waves whereas a VSS is a generated electrical voltage signal.

If it were easy to meld those two very different devices surely all the new cars would be using GPS powered VSS - but they aren't...

Its pretty simple to put a VSS generator in your speedo head or on the inboard CV joint.

Mon Oct 15, 2018 2:42 pm

The GPS speedometer senders I'm familiar with put out 16000 pulses per mile, which would probably freak out the Suby ECU...

Mon Oct 15, 2018 2:52 pm

Howdy,

I think I understand your question now.

The simplest way to obtain a VSS signal is to use a sensor on a CV joint. I know not all conversions are the same, but in the Bostig conversion (for example) the VSS signal is generated by an installed flange on on inboard CV joint, with a sensor bolted to the transaxle. The sensor is used in a binary fashion: it only needs to know if there is motion or no motion. You can also use the sensor signal to drive a speedometer in an Ultragauge or similar product--and would require calibration with a GPS.

GPS speedometers are getting their speed readings from GPS receivers, and are usually manufactured in the context of either not having or not wanting a VSS in the instrument cluster, but I admit I would also be interested in a GPS speedo that passed configurable VSS signals for ECU or cruise control use.

If your Subaru conversion needs a VSS, see this Youtube video about a poor man's VSS for a Subaru conversion.

At first I thought you might need a VSS for cruise control functions. Dakota Digital makes a device that dumps speedo and tach signals from OBD, which might be useful. I have Speedhut gauges, including a GPS speedometer, and so I have to use a device like this to serve data to my aftermarket cruise control computer, as I no longer have a mechanical speedometer cable.

I hope this helps.

kourt

Mon Oct 15, 2018 5:22 pm

Beautiful. Thank you.

Mon Oct 15, 2018 9:04 pm

There are GPS devices that turn a cable at a configurable rate to operate vintage speedometers. I saw them a time or two at the vintage car swap meet in Portland but know nothing else beyond their existence. Something like this link: https://www.speedhut.com/ecommerce/product/2585/SPEEDBOX™-GPS-VSS-to-Mechanical-Drive-Speed-Converter

Tue Oct 16, 2018 8:19 am

kublerwagen wrote: There are GPS devices that turn a cable at a configurable rate to operate vintage speedometers. I saw them a time or two at the vintage car swap meet in Portland but know nothing else beyond their existence. Something like this link: https://www.speedhut.com/ecommerce/product/2585/SPEEDBOX™-GPS-VSS-to-Mechanical-Drive-Speed-Converter
Those are for Ford, GM and Chrysler vehicles only - and $345.00.