67 Speedo bounce

[Dereck S.]

My 67 4-speed speedo needle bounces +/-15 mph at all speeds as I go down the road. It used to do this only occasionally at lower speeds. Now it does it at all speeds all the time. It is extremely annoying. It appears to be the original cable (nuts have correct AC markings). My guess is that the rotating cable is getting hung up as it goes through its rotation likely at bend points. Would a repair for this condition be as simple as removing the cable and injecting oil down the outer sheath for lubrication or will this require a new cable? I don't want to remove it twice.
Dereck

[Jack H.]

Re: 67 Speedo bounce

A frequent issue... The first point of attack is to clean and re-lube the speedo cable. Lubricant inside the sheath has a definite life time and when it dries up, it needs to be refreshed.

There are several threads in the archives on 'how to', but the big picture is this maintenance can be done on-car! You detach both ends of the speed cable and extract in inner core from the sheath.

Next, I recommend flushing the sheath to expel old dried lube. Brake cleaner works. When done, blow the sheath clean/dry with compressed air.

Now, clean the inner cable and apply your choice of speedo cable lubricant. Your local auto parts store will have several alternatives of lubricant intended for this job, plus threads in the archives have member recommendations on what they like.

Last, re-thread the inner cable into the sheath gently twisting it as you go to get around 'corners'. Reconnect both ends of the speedo cable and take 'er out for a drive to exercise and spread the fresh lube...

[Bill I.]

Re: 67 Speedo bounce

And remember, do not lube the upper 12" going to the head, the lube will wick itself. Bill

[John S.]

Re: 67 Speedo bounce

Derek,

Had the same exact problem last year. Lubed cable to no avail. Turned out it was the 1st stage worm gear that drives the odometer /trip odometer gears. If relube does not work, search here and the web and you will find instructions on cluster removal. Take the earlier advice and do not over lubricate or lube to high on the cable. It will "rope" up the cable and end up in the speedo magnet cup area and then you will really see some weird stuff! Ask me how I know! If this does happen, you will have to take it apart and clean thouroghly. Do not use carb cleaner. I did and when I put it back together my completely rebuilt and calibrated speedo was off a whoping 10%. (it had been acurate to within less then 1 mph off at 70 mph) Took it back off a third time and back to the speedo shop and he recalibrated (remagnatized) it and it works perfect now. He explained that some carb cleaners will demagnetize the head. Been doing it for over 30 years and he new exactly what happened when I brought it in. Nice guy and re did it for free. Good luck!
John

[Dereck S.]

Re: 67 Speedo bounce

Thanks for all the advice. There's no substitute for experience. I'll have a go at it this weekend.
thanks,
Dereck

[Peter S.]

Re: 67 Speedo bounce

By the same token, I had this problem and didn't do anything to the cable. Had the speedo restored, plugged in the same old cable and it holds rock-solid. So it might be something in the speedo itself. Assume that's the next step after trying the cable lube. I used D&M restoration.