I'm looking for a Vehicle Speed Sensor VSS to fit onto a 1979 RX7 5 speed manual transmission. Has anyone found a VSS that fits or options for one? I will be connecting it to a Haltech ECU that will display on a PowerTune digital dash.
My other option is to fit a sensor to look at the drive shaft or one of the wheels to derive a speed signal. Worst case is to use the GPS for speed but I'd prefer a direct indication.
TIA

 

Subscribing to the thread as I'm curious as well. Particularly if such an option exists that retains the factory speedo drive.


As far as options go, I recall having seen something that the FD speedometer sensor might work in the earlier transmissions, but I can't say that for certain. Hopefully some other folks may chime in on that.

The other idea I had back when I was thinking of this was to add a hall sensor and trigger wheel on the driveshaft cooling shroud since it always stays in the same place. Just a thought anyhow.


Edit: Just had another idea, although this isn't a short term off the shelf solution. There are some vehicle speed sensors that work inline with the speedo drive cable. I'm not sure if you intend to use the original speedo still, but since I do, I bet I could make a new enclosure and drive spline for one of various sensors out there (such as an SMP SC46) and make it fit in-between the transmission speedo gear and the factory speedo cable. It entirely depends on how it's assembled, but for less than 20 bucks I'm probably gonna give it a shot. That's perhaps not the solution you were looking for though, so hopefully some other folks chime in on more standard solutions.

 

The stock speedo might have a VSS output to the emissions computer. I know the later 1st gens definitely do.

Alternatively, one from a Miata may work. https://www.tascaparts.com/oem-parts...sor-m52817400a

 

I'd love to know what you come up with. I have same issue with my REPU. The Miata solution doesn't work if you want to retain your factory speedometer.

I kind of worked around this issue because I only needed to know when to go into idle loop, or more specifically, when was the truck in neutral? I did this by assuming RPMs below 1,200 with 0% throttle was neutral and used the digital logic inputs/outputs on my Adaptronic ECU to set this up. It worked so long as the motor drops down below 1,200 RPM by itself and then idle kicks in and cuts timing until it reaches target idle speed. The second you touch the throttle, it kicks out of idle loop.