Speedometer cable bounce part 2....what I have learned. 79Z

I've got a two piece speedo cable in in '78. When I did the interior over a few years ago, I installed a 150mph speedo I picked up on eBay. It bounces from 0 to about 30, and then levels out. When I first installed it, I had an awful squeel too. I was leaving for the Syracuse Nationals the next day, so I decided the best way to fix it would be to peg the needle and see if it wrung the problem out. Headded out at dusk to a seldom-travelled road with about a 50mph speed limit without any houses on it. Opened it up, got to about 70-75 before I saw the blue lights in the mirror. Rolled down the window and the cop said he heard me coming way before I blew by him. Fell on the sword and told him the truth - trying to wring a squeal out of the cable before I head off to the big car show. I guess he wasn't expecting that. He told me to drive home at the legal speed and have a good time at the car show.

The squeal went away, but the bounce never did. Someday I'll get around to replacing the cable, but for now, I'll watch this post to see if you figure your problem out.

 

Congrats! Nice to have things working as they should. Tall order with a 40 year old car.

 

I'm not sure what the cable connection looks like at the speedo end, but I wonder if the inner cable isn't seated properly in the drive gear. I've had it happen on other vehicles. It feels like it seats and looks like seats, but it's not engaged enough. Could also be the case at the tranny end. On some applications, the inner has a ferrule that prevents it from being pushed too far into the guide on install. I don't know if this cable has it.

As has been pointed out, pull the tranny end and spin it. If it doesn't work right, try fiddling with the inner and try to seat it?

 

I think those gears are all plastic, aren't they? Probably a good chance for a point of failure.