1969Stangman

Hello,

Reposting in the correct Forum.

I own a 1969 Mach 1 “R” Code with an automatic and air conditioning. I’m having issues with my speedometer. I recently had to replace my aging cluster circuit board. The repair shop broke the clip holding the speedometer cable to the back of the speedometer gauge and installed a new cable. Prior to the new speedo cable being installed the speedometer gauge functioned properly. My first series of issues after the the new speedo cable was installed were as follows (comparing my GPS speed) to the gauge:

1. The speedo gauge needle would not move until I reached a speed around 15 – 20 mph. It would then jump up and gradually match actual speed.
2. If I maintained a steady speed around 50 mph or higher the needle would slowly increase to 90 mph and keep going.
3. When I stop the needle would not return to zero but remain at around 15 mph.
4. When I jiggled the cable from inside the engine compartment the needle would drop to zero.

I suspected a bad cable and returned to the repair shop. They replaced the cable with a new one which created a new series of issues:

1. The speedo gauge would not move until I reached 20 mph. Then it would begin to move upwards but never reaching or matching actual speed. Under 40 mph (gauge speed) the needle would always be lower than actual speed; e.g. gauge reads 20 mph and actual speed is 35 mph.
2. Maintaining a steady speed of 50 mph or more the needle would increase quickly to around 90 mph.
3. If I go over road bumps or railroad tracks the needle would bounce higher and lower and then steady itself after a few passes but never matching actual speed. This occurs more frequently at higher speeds. This was a new issue.
4. When I stopped the needle returns to zero.

The repair shop performed the following troubleshooting steps:
1. Replace the speedo head gauge – no improvement.
2. Removed the inner cable and greased it - no improvement.
3. Replace the plastic speedo gear at the transmission – no improvement.
4. Inspected the transmission out gear – appears to functioning properly.

Anybody have any ideas how to fix this?

Thanks,

Larry

69mach1377

"The repair shop broke the clip holding the speedometer cable to the back of the speedometer gauge and installed a new cable. Prior to the new speedo cable being installed the speedometer gauge functioned properly."
This seems to be the root cause. Everything after that incident does no good.

bop11

The shop destroyed the bearings in the speedo. It will need to be replaced or rebuilt.

1969Stangman

Finally my speedo issue has been resolved. It was the darn 'after-market' speedo cable. Took my original speedo head to a local speedometer shop and they bench tested it. Speedo head worked perfectly. They knew exactly what the issue was and made me a new speedo cable for $40 in 15 minutes. Took the 'after-market' crap out (both the speedo head and cable). Now it works like a charm. Explanation: the speedo shop informed me that the after-market cables begin to retain a memory in the cable after being stored on the shelf for long periods of times which causes them to bind/rub against the housing. Oh and by the way. The repair shop reimbursed me for the the 'after-market' parts and most of the labor. Guess I'll still do business with them. lol

fastbackford351

That's the kind of place you want to do business with. Even if they make a mistake, as long as they stand behind their work and make things right then you know they are acting in good faith and not trying to get over on you.

Good to know that about the repop cables.

69mach1377

The cable I got from CJ PP solved my wobbly needle problem.