odometer, speedometer out

[LanceB]

Okay, mileage and speed stopped working again on 77. Had it fixed awhile back by mechanic. Hate to take it down there and wait a month and also hate to take dash apart. It sounds like I can here something behind it that makes a funny sound when idling, then changes with speed. I was hoping it was just a vacuum or cable loose, (not real sure how this thing works), but can't find anything. Anyone have any ideas? It does have cruise control, which doesn't work.

 

[Vettehead Mikey]

Have you removed the drive cables to inspect each end? There's an upper and a lower cable on cars with cruise. If the lower cable is broken, it could be your cruise unit is seized.

 

[timme69680]

Vettehead is right on the money here. One thing you said makes me suspicious is that it is making noise. Your car has a cable that runs from the back of the speedometer down to the transmission. The cable itself is basically an outer plastic shell that stationary whilst internally it spins with the speed of the transmission. There is a gear that is in the transmission that turns one end of the cable and the speedometer is calibrated to determine speed based of revolutions of the gear. The gear will not be spinning unless the car is in gear.

I would first find the cable, make sure it is securly fastened to the speedometer and the transmission. If the problem still exists remove the cable test that if you spin the transmission end the speedometer end turns. Verify that each end is not worn or broken. The next question would be the gear that turns the transmission side of the cable. I am not really sure how you can test if that is working. The only other thing i can think of would be to only unhook the transmission side and leave the cable attached to the speedometer and see if you can spin the cable fast enough to see the speedometer move. If the cable is good, and the speedometer moves when you turn the cable then the gear in the transmission may need to be looked at.

 

[LanceB]

thanks for the replies, hopefully I can figure something out. Until then it sits in the garage. No fun to drive unless you know how fast you're going