speedometer functionality

57 Chevy truck stock gauge. If I insert an old speedo cable to the gauge and drive it with an electric drill turning righty to tightey, what should I see?

1. Speedo and odometer turn
2. Cable locks up tight and doesn't turn cause I need to reverse the drill
3. Speedo nothing, but slow odometer

I tried it on one of my 3 gauge sets and going either way locks up, doesn't turn. I don't want to ruin anything else.

 

You want the drill spinning in the same direction of the needle sweep, so that would be CCW when looking at it from the back of the speedo. You don't need to spin the drill very fast so a variable speed drill is needed. And yes, the odometer will also be activated by the spinning as it is gear driven internally within the speedometer.

It sounds like you are trying to spin it too fast and also going the wrong direction.

Don

 

Thanks Don

 

Take the speedo out of the cluster. On the speedo shaft you should see a very small brass sledge plug. Remove that plug. Put some 3 in 1 oil in that hole let it soak a minute. Then add some more oil. Run the speedo. After a little run add more oil. Let it set a few minutes. Run it some more. That should ol the speedo shaft. Put the plug back if things work better. If not send it to speedo shop.

 

To ad to what Don has said, you can usually get the needle to move spinning it by hand. I used to use a carpenters brace to test them once I bouced the needle by spinning it by hand. If I coudl crank it up to 45 or 50 without it waving at me much I figured it was good.

 

1000 RPM is 60 MPH on most speedo's.

 

run the drill in reverse.

no worries about going slow. Full speed on my drill is about 70 mph on a functional speedometer.

we find some that are locked up tight and the cable is broken. We have a short length of old cable that we insert into the back of the speedo. Clamp on a small vise grip and gently work it. More times than not, it will free up.

 

Thanks everybody, can always count on you!

 

What Bobwop said--my cordless makita is 65 MPH at full trigger on stock 40 Ford speedos-make sure it's in reverse

 

Last one of three worked! First two broke free easier but the third came from a sealed gauge set that was included with a bunch of other parts I picked up. Can't wait to see how it works tomorrow.

Thanks again!

 

Your shoes will do a smokey burnout on the garage floor.

 

best line all day

 

Good news and bad news. Bad news first, the speedo works but not 100%, hell not even 50% of the time. Good news is I found a repair guide here for the 57 car speedo that 'should' help repair 1 of my 3 broken ones.