Yellow Trike Speedometer and Starter

Speedometer:

I installed the VDO speedometer with a 4 pin weatherpack connector. I was concerned about having to splice into power and ground for it, but I just used the wiring for the old speedo's lights. Power and ground right there. Internally, I wired the lights and speedo power together.

I wound my own pickup coil. Using a drill mounted in a vice to roll the form, I first used the entire 200 foot roll of 30ga magnet wire, but where I was originally going to place it, it was going to be too long. After I unrolled it (yes, as clumsy as it sounds), I wound a new coil with the same wire that was really a nicer coil, but smaller. I then essentially soaked it in black spray paint for both weather resistance and to stabilize it against vibration and spun it slowly in the drill under the heat of a 250W work light to dry.

Once I had it in hand, I discovered a much more elegant place to mount it, using one of the front brake caliper mounting holes. This hole is in near perfect alignment with the 5 bolts that hold the hub and spokes of the wheel together. I mounted 5 rare earth magnets to the bolt heads with 3M mounting tape and mounted the coil with about a 3/32" gap between the bolt head on the coil and the magnets.

I put the meter on the coil. It reads 14 ohms. When I spin the wheel manually, I see the pulses, but they seem smaller than I would expect.

I did a little math to figure out how many pulses per mile this setup would provide. Divide the wheel and tire circumference (7 feet even in this case) into 5280 to get how many wheel rotations are in a mile, 754.3, then multiply that by 5 magnet pulses per rotation to get 3771. Following the directions for manual calibration of the speedometer, I set it to 3770. The speedo always forces the last digit to a zero. Shrug.

So, I had the front end up on the jack with the speedometer powered up and spun the front wheel.

Nothing. I spun it as hard I could and still nothing.

I wasn't completely surprised, considering the small signal from the coil.

I did find accidentally, while testing the timing on the road, I looked down an the speedometer was indicating! Turns out my coil is too small and doesn't provide a large enough signal to count at low speeds. Above about 40 mph and it works great. I tried using an audio transformer connected in reverse to boost the voltage a bit, but it doesn't work at all then.

I have the stuff and dimensions to wind a new coil. I expect it to be about 25-30 ohms and probably double or more the signal.

If *that* doesn't work, ok, I'll *buy* a VDO pickup....

The entire speedometer assembly is fairly mobil in operation. I made a brace to help hold the dashboard still, but it turns out that much of the speedometer movement is in the speedo's own mounting bracket. I'll think of something.

More coil details tomorrow.

Starter:

The verdict is in. I'm pretty sure that the starter flakiness was due to overloading the starter button contacts and thus eventually burning the switch out. I got a grounding type button and rewired everything with a relay instead of direct and it did not fail in 30 start.

I know that the original starter needed replacing, but I'm not so sure the 2nd one did.