QuestionThe speedometer works perfect with the wheels off the ground. I jacked it back up again today and tested before I started tearing stuff apart and it worked! So I let it down took it for a drive and it did nothing.
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My speedometer was jumping. I purchased a new one as well as a new cable. Installed them last night, I had the back end jacked up and the speedometer unscrewed from the dash. It worked perfectly. When I let the back down, screwed it into the dash and took it for a drive it didn't go anywhere?! What could have caused this to happen? Everything is new except the gear that plugs into the tranny but it was fine. It worked before I put the back down. I am soo confused. Please Help!
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My guess is that something became disconnected, at one end or the other, when you lowered the car off the jacks.
To investigate, take the cable out of the back of the speedometer head and see if you can turn it freely - if so, it isn't making contact with the driving gear in the transmission.
If you can't turn it more than a small amount (the cable will flex a tiny bit, but you'll feel resistance if it is plugged in down there), then get someone to drive the car a few feet while you watch the end that goes into the speedometer head.
If you DO see the cable turning, then the problem is that it wasn't making contact with the mechanism inside the speedometer head. Maybe the cable is a bit too short, or maybe it just wasn't seated all the way into the head - you'll have to just be a detective and track it down.
If you are sure it is turning where it goes into the speedometer head, and is seated all the way into the fitting, then something must have quit inside the speedometer. Pay attention to see if both the odometer and the speed indicator are not working - if so, the problem is probably right where the cable connects. If the odometer is working, but the speed indicator isn't (or vice versa), the problem is clearly inside the instrument itself.
Dick
AnswerIt's good that you were able to reproduce the problem, at least it is consistent.
But there is nothing more I can add as to how to track it down - something is coming disconnected when you let it down off the jacks because of the way things move under there. You need to find out which end of the cable is coming out of it's socket.
Dick
