1978 k20 spedometer not working?

[dmartin1]

so the spedometer never worked ever since i bought the truck.

i replaced the cable from the cruise control box thing on the fender well to the tranny/transfercase.

the spedometer then started working for a few miles( like 5) and then stopped and hasnt ever since.

What do you thinks wrong and how can i trouble shoot this?

the cruise control box thing? the cable from spedometer to the box thing?

is there a plastic gear or something inside the tranny/transfercase thats bad? i need help lol

i cant tell how fast im ever going! ah!

[76stepsidechevy]

There was a ratio box on the side of my trans to calibrate the speedo that was stripped out on mine. I guess you cant just swap out the speedo gear for different tire size or gear ratio?

[dmartin1]

I wonder if I could hook an electric drill to the output square inside cable to see if the spedometers still good and just go down the line? I don't see why it wouldn't work..?
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[Pop's C-10]

Lose tha cruise box all together & use a 1 piece cable..

[76stepsidechevy]

Originally Posted by dmartin1

I wonder if I could hook an electric drill to the output square inside cable to see if the spedometers still good and just go down the line? I don't see why it wouldn't work..?
Posted via Mobile Device

I actually was going to suggest that before, ive done it and it works just don't go too crazy with the drill speed.

[dmartin1]

excellent i guess ill try that with the drill and find out what the problem is, should be easy to trace down the problem.

either way that box is leaving and im gonna run just one cable.

is there a gear inside of the tranny/transfer case where the cablethreads onto/slides into?