Bench running a speedometer

[JeepsAndGuns]

So a couple weeks ago I bought a 94 jeep cherokee XJ for my GF to drive back and forth to work. I will also drive it every now and then too. Its a base model cherokee and on those the guage cluster only has a speedometer, fuel guage and then dummy lights for the rest. All the models above the base model have speedo with trip meter, tach, fuel, oil pressure, coolant temp, and volt meter. All you have to do is remove the base model cluster, plug in the better cluster, then change the oil and coolant sending units. Real easy swap. Its driving me nuts not having a tach and the other guages. I hate dummy lights.
So I found one in the local pull a part for cheap. Had like 272k on it. Well the cherokee I bought only has 150k. So being OCD and annal, I had to have the mileage right. So I dismantle the speedo and start trying to find a way to run the miles back. I found if I just spun the gear for the miles (its a electric speedo, but the miles are mechanical) by hand backwards it worked, but it was going to take forever. Long story short, I try a couple different ways of speeding it up (one involving a dremel tool) and lock it up from spinning it too fast
Fast forward a week and I have another cluster in my hands (from ebay). I lucked out and this one has less mileage. (135k) Since I paid a good bit moroe for this cluster (more than I really wanted), I dont want to screw it up (no taking it apart) It came with the pigtails from the wiring harness, so I used the wiring diagram and found the power and ground wires, also the speedo signal wire. I also have a spare speed sensor. Its a hall effect sensor, (8ppr) So I used a old computer power supply, used the 12 volt for the speedometer, and the 5 volt for the sensor. I can spin the speed sensor with my cordless drill and it works!

SO, heres my idea. What I would like to do is find a way to just run the speedo and let the miles naturally roll up on the cluster. The speedo maxes out a 85 mph. If I am reading the sticker on my drill correctly, it maxes out at 1400 rpm, this put the speedo at about 70mph. I have calculated out, that if I could run the speedo at 85 mph, it would have to run for 24 hours a day for a hair over a week to make the mileage correct. But naturally I cant use my cordless drill for this. The speed sensor has a square male shaft sticking out of it (same size as the old speedo cables) So here is where I need some help. I need to find some type of small electric motor I could maybe vary the speed on that I could somehow attach to the speed sensor. I have been thinking about what I could use and cant come up with anything. It doesnt have to be very big or powerful, as the vss is real easy to spin.
So, anyone have any suggestions?

For reference, here is a pic of the speed sensor I need to spin.

speed-sensor-56027905-a1_6368.jpg

[steveo]

just generate the signal. the soundcard in your computer may be sufficient for this task.

[dave w]

Drill a hole just big enough for the square to fit in some round stock. Then drill / tap two set screws to lock the square inside the hole. Attach the drill to the round stock.

dave w

[Six_Shooter]

Drill a hole just big enough for the square to fit in some round stock. Then drill / tap two set screws to lock the square inside the hole. Attach the drill to the round stock.

dave w

Why would you go through all that trouble when you can just insert the tang into a drill chuck?

[steveo]

ahhhh just generate the signal

i betcha you could just record the signal from the vss with the soundcard input, loop it, and play it on output

just dick around with the gain (volume) till it actually accepts the signal and moves the speedo

mechanical solution to electrical problem bad

[Six_Shooter]

ahhhh just generate the signal

i betcha you could just record the signal from the vss with the soundcard input, loop it, and play it on output

just dick around with the gain (volume) till it actually accepts the signal and moves the speedo

mechanical solution to electrical problem bad

Yep, that's definitely possible, though I would use a function generator if it were me. Sometimes the simple solution to some people is the mechanical solution. ;)