Inaccurate Tachometer?

[infernosg]

Originally Posted by C. Ludwig

The FD and Miata trans senders use a VR sensor. If one swaps to the NA trans it would work with an A/D converter.

There is nothing really better about a Hall sensor. VR sensors generally are preferred for something like wheelspeed where there is a high resolution target. Just need an A/D converter for your gauge and ECU that want to see a square-wave input.

I'd love to get my hands on a Miata VSS. The N/A RX-7 transmission is nearly identical to NA and non-Mazdaspeed NB Miata transmissions (I have the Miata guts in my transmission to prove it) so I imagine it would bolt right in.

I forgot all about the A/D converter. The speedometer I have says it can use a signal from either a VR or Hall effect sensor as long as the signal is 3V peak-peak. I'm sure the VR input would be slightly irratic if not wired absolutely perfectly so the A/D converter is probably a good idea nonetheless.

Originally Posted by TitaniumTT

I believe its called Speedometer solutions in MN or WI or somewhere around there. They have a unit (or they did anyway) that will thread into the tranny where the cable did. It outputs a hall effect signal that just about any aftermkt speedometer will read an interpret. Cost when I bought it some 7+ years ago was like $75. Worked really well for me until I went full traction control and needed inputs from all 4 wheels. This option will give you driveshaft speed which will get interpreted as speed.... not useful at all for traction control.

I did a quick search on the other forums and found a few hits. Latest seemed to be from 2010 and the mentioned cost was ~$100. Considering that's less than a new Miata VSS or a used ABS hub and it wouldn't require a A/D converter it's worth a call. Do you have any pictures of the unit you had or any knowledge of the pulses/revolution?

[infernosg]

Originally Posted by infernosg

I did a quick search on the other forums and found a few hits. Latest seemed to be from 2010 and the mentioned cost was ~$100. Considering that's less than a new Miata VSS or a used ABS hub and it wouldn't require a A/D converter it's worth a call. Do you have any pictures of the unit you had or any knowledge of the pulses/revolution?

In case anyone is curious I spoke with Speedometer Solutions yesterday and they still offer the converter. It attaches right to the stock mechanical speedometer driven gear housing and generates a digital square wave signal with 16 pulses per revolution. Three-wire hookup: switched 12V power (red), ground (black), and signal output (white). $98.50: