Very Strange Speedometer Problem -- Anyone Ever Seen This?

[focodave]

So I wanted to swap out my 1980 85MPH speedometer for an earlier 1978 140MPH speedometer.
I replaced my dash earlier this year and was able to easily remove the speedo cable from the speedo, no problem.
In the course of replacing the dash, I was able to reinsert the cable and lock it in place just fine with the plastic outer sleeve pushed toward the back of the speedo housing to lock it in place.
No drama --- no problems --- all was normal.
Now, months later, I as I try to remove the speedo cable from the 85MPH speedo, it simply won't come off no matter how much reasonable force I apply.
I pulled the outer sleeve back to release the multiple plastic fingers that engage the groove around the perimeter of the cast boss at the back of the speedo, pull with every ounce of strength I have, and the cable will not come out of the back of the speedo.
Has anyone ever experienced this and if so, how did you get the cable to come out of the back of the speedo?

[So Cal Mark]

78 and 80 use different cables and methods of attachment. The 78 style uses a threaded end, so I would expect the fingers on the 80 cable are locked onto the threads

[focodave]

78 and 80 use different cables and methods of attachment. The 78 style uses a threaded end, so I would expect the fingers on the 80 cable are locked onto the threads

Actually, my original 1980 unit and the 1978 unit use the same method of attachment. Here are some pix of the 1978 unit:



The original 1980 unit is the one that is "stuck" and won't come free of the cable. I am able to pull the outside collar back about 1/2" and expose the fingers, and also I am able to pull the whole housing back about 1/2" with the fingers released from the groove. It seems like the cable itself is not releasing from the rotating shaft inside the speedo. It came apart and went back together just fine a few months ago.

[81SPIDERMATT]

will rocking the car back and forth while in gear spin the cable ever so slightly and maybe "pop" it loose while you hold the speedo in hand ... I know where someone is that would help

[focodave]

Matt,
Many thanks for the offer to help.
I already put everything back together with the original speedo still in place (yesterday), so I could drive the car.
I still am looking to see if anyone else has experienced the same problem as it has me completely baffled.
I've had the original speedo in and out of the car several times in the past without any trouble, so it's not like I don't know how to remove or install it.
Right now I am resolved to just staying with the original "sucky" 85MPH unit until I get ambitious again to rip things apart.
The old one works fine -- I just wanted a cool 140MPH speedo in the car because I like the way they look.
I may just buy a new cable for the 140 unit and replace everything in the near future.

[vandor]

The change from threaded to clip-on occurred in mid-77, when they also changed from the deep set gauges to the less deep ones. Then in mid-78 the cable was routed through the firewall instead of the trans tunnel, so there is a short and a long clip-on type cable.

[bradartigue]

I like the 85 only because it always looks like you're going fast...