I have a 74 stingray 4 spd

I was out for a drive recently and i went to flip my high beams on to make sure everything is in working order and once i hit them on i noticed my speedometer wasnt working. I recently check to make sure the cable was connected to the speedo and it seems to be, also i checked the cable underneath the car, i unscrewed the union between the two sections of cable and it seems like the cable is still whole / no breaks. i cannot figure out the issue...any ideas?

Also since ive had the car the tach doesnt seem to work either. It appears to be stuck at about 1800 rpms. But ive been noticing that right before the car fires the needle will drop to zero and than bounce back up.

Any suggestions or tips please let me know.

 

Have you tried connecting either cable to a drill and tested the gauge? I believe the correct rotation is counterclockwise.

 

Several points of failure are possible:

1. The teeth on the speedo drive gear [on output shaft of transmission] or on the speedo driven gear [the one the cable fits into] could be sheared off and not allowing cable to rotate.

2. The recess in the shank of the speedo driven gear has 'wallered out' so that it no longer drives the cable.

3. The cable is broken somewhere inside its sheath.

4. The speedometer head is defective.

You can figure this out with ONE test. Remove the speedo cable connection from the speedometer head. With cable pushed fully into the end fitting, try to rotate the cable; if it won't turn, the speedo drive gear is not wallered-out (old Hoosier term for 'stripped') nor the teeth on the speedo gears are not sheared off. If the cable turns, the opposite possibilities are possible.

Also, pull the cable out a few inches, then insert the end of the cable back into the speedometer drive socket. Now spin the cable and see if you get any movement on the speedo needle. If you rotate it in the reverse direction and see some 'wiggle', spin it in the other direction to check the speedo needle for movement. If you get some reading with manual rotation of the cable, the head is not completely defective.

You can also pull the cable completely out of the sheath from the speedometer end so that you can check for unusual wear, breakage, binding areas, etc.

If the speedo drive/driven gears appear to be the problem, the driven gear is MOST likely to be at fault. Remove the cable end from the transmission connection; then remove the module that contains the driven gear or the gear itself (depending on transmission) and inspect the teeth and the socket at the cable end. That socket can crack at the corners of the cable socket and no longer retain the cable when the gear is spinning. In either case, replace the driven gear with one of sme color and number of teeth.

Good luck on your dianosis and repair.

 

7t1vette

I took another look at my situation and atleast as far as i can see part of the speedo cable has considerable wear on it along the but up more in the engine bay. the cable itself seems to still be intake. I disconnect the two cable (the speedo cable as well as the cable coming off the trans) i gave the actual cable on the speedo a pull and it seemed to be all in one piece.

I have yet to pull the dashboard out and check the gauge itself. When pulling out the dash ive notice that it is a slight pain to get it over the steering column. I read that you need to lower the steering column..is that true (if so how is that done) adn if not what is the best way to remove it.

when i tried to rotated the cable from the other side (underneath car), it didnt rotate...according to what you mentioned earlier that means the gears are most likely intact..correct?

How often do the actually gauge itself go bad?