Bouncing needle. I lubricated with white lithium grease as recommended by many and it made it worse...to the point of making noise in the gauge at more than 50 mph. So I pulled the inner cable, wiped it off, ran it in several more times to remove as much of the the lithium grease as I could. Then tried some light silicon oil (500* temp rating) like the speedometer cable lubricant I'd use decades ago and that smoothed the speedometer needle out beautifully....for about 10 miles. Then it went back to bouncing but not as bad. The inner cable doesn't appear to be worn, nicked or kinked in any way and easily engages with the transmission. With the lighter oil it definitely spun by hand with much less resistance. When I used the lithium grease I had a bad feeling about it.

What are you guys using to lube the speedo cable? Anybody use graphite powder?
Is it possible/likely that the inside of outer cable is worn or nicked?
Any tips clean old the old grease/oil out of the outer cable other than a solvent bath and dry?
When I pull the outer cable off the transmission, is it going to drain the gear oil out? Not a problem, since I probably should change it anyway. Just want to be prepared.

Thanks

 

Rookie reply: Thicker grease causing it to worsen makes me think several things you mentioned are causing problems.

Remove the cable from the transmission...use a LOW SPEED drill to spin the inner cable at 60 mph...........Does the fluctuation still happen?

Look into the female square hole in the transmission.......Does the hole appear to have "rounded corners"? Does the end of the inner drive cable appear to have rounded corners?

Let us know what you discover.

I use only a VERY THIN coat of bearing grease on my inner cable.

 

I used spray graphite and kept spraying until some liquid came from the other end. Did this one about four years ago to fix the wobbly needle that quickly progressed from minor to virtually the entire speed range. Never had to touch it again.

 

The inner cable didn't have rounded corners at either end so I don't think it's slipping. Plus, when I added the thin oil, the bounce went completely away, if only for a short time.

Since you said you used a thin coat of grease, that may have been my problem. Too much grease. I'll get it up on the lift this weekend and pull the other end to see if I can clean it out and start over.

Or I can get a new cable locally for somewhere between $12 and $18, so I may just push the easy button.

 

Like this? Says it spray on wet and dries quickly.

 

Molybendum disulfide grease.....The dark grey metallic stuff. I used to work at a factory that made similar....that's what they used.

https://www.grainger.com/product/2F1...YUPY8:20500731

 

Try the electric drill test to eliminate the transmission gear as a source of the problem.

If you are ok with pain....unplug the cable from the speedometer AND the transmission....

Then use the drill test to feel any "twitches" in the cable housing or the square cable core.

There is also a tiny geared shaft INSIDE the speedometer that can wear out and cause noise/twitching.....but checking that would be the LAST resort....

Replace the cable first

 

Dry graphite is the only thing that SHOULD be used on speedo and tach cables. Grease will gum up the cable/sheath and make cable drag much worse. You need 'lubricant'...not goo.

Grease works well to lube metal parts with high loading. ANY drag inside the sheath is a loser.....

 

This makes sense. I'm not sure why I keep seeing white lithium grease as a recommendation or why I followed it. I'll see what I can do to clean up what I have and use the graphite or moly dry spray.

 

That's the ticket....