Mounting the Zolox Sensor

After futzing around awhile, I was able to get the spacer ring for the Zolox tachometer sensor to line up.


Here's the bottom of the mounting ring. The screws that came with the mounting kit stripped out the plastic, so I sunk some depressions in the backside of the ring where the bolt holes were and put in 8-32 x 1" bolts from the backside.

Notice that the large holes in the upper left and lower right are somewhat warped. I had to use a drill to hone out the holes in the proper direction so that the ring was actually centered on the motor tailshaft.


Here's the topside of the mounting ring with the Zolox sensor bolted to it with nylock nuts. There's actually a space between the black flange on the sensor and the mounting ring, so don't tighten these bolts too tight. The grey mount on the lower right holes the wiring so it doesn't flop around.


I drilled a hole in the center of the tailshaft and then used a 1/4" bolt to align the magnetic disk with the hole. I didn't have a tap to put threads in the center of the shaft, so I just epoxied the whole thing on, using the bolt to keep the magnetic disk centered.


Here's the sensor assembly bolted onto the motor over the tailshaft. The bolt holes had a little play to them, so I had to make sure thing were lined up. I put the Civic in third gear and blocked one wheel so that I could rotate the hub to spin the motor shaft. After spinning the motor shaft and verifying that the magnetic disk didn't rub up against the inside of the speed sensor, I tightened down the bolts.


The sensor comes with a shielded cable with three wires. Red is +12V, black is ground and white is an active pulldown. My test setup shown here includes a small 12V battery on the right (from an old UPS) and my multimeter. I added a 2.5K resistor to pull the white wire up to 12V when the sensor wasn't actively pulling down. Surprise! It actually works and generates high and low voltages as the motor shaft spins. The real acid test will be to see if it triggers the SpeedHut tachometer properly.