'61 Speedometer needle bouncing

[Art B.]

I couldn't find this subject in the Search section. My "61 speedometer needle bounces at speeds about 35 to 50 mph. At other speeds it is steady. Anything else I can do besides lubricate the cable again? I had the speedometer rebuilt several years ago and it was fine for after that, until now.

[Joel F.]

Re: '61 Speedometer needle bouncing

Hi Art,

Have you lubricated the cable lately?

[Jack H.]

Re: '61 Speedometer needle bouncing

I can see, perhaps, three issues that would lead to excessive speedo needle bounce.

(1) The inner cable is running dry in the outer sheath creating too much friction. The corrolary is lack of proper lube resulted in the outer sheath becoming abbraded and you've got loose strands inside that are trying to 'wrap' around the inner cable. All the fresh lube in the world isn't going to fix that situation now...

(2) Due to lack of cable lube, the drive end of the speedo cable has 'rounded' and it's now slipping. Drive cable ends were square in shape and slid nicely into their mating drive components with a slight interference fit. The solution is to pull the original inner cable and replace it with a fresh one available at any local auto parts store as a speedometer cable repair kit available in various 'cut to fit' size increments.

(3) The speedo head in the speedometer needs to be serviced. Speedo repair shops clean and freshly lubricate the internal components and the good shops have test/exercise machines to check calibration, set the air gap between the magnetic drive and driven components as well as re-magnetize the speedo's drive component...

[Joel F.]

Re: '61 Speedometer needle bouncing

Another thing that can happen after storage is the lube dries up, and the added friction causes the spinning cable to bind and release, bind and release repeatedly causing some bounce. If the speedo was fine before storage and the problem has cropped up suddenly, hopefully the lube will fix it.

[Troy P.]

Re: '61 Speedometer needle bouncing

I suspect the speedo head needs lube, not the cable. I've seen this before in a 57 Caddy. Take the speedo out and you'll find a plug in the side of the drive mechanism just outside the housing. Take the plug out and hit it with two drops of 3-in-1 oil. If you can't get the plug out you can often get enough lube into the housing by soaking the end of the drive in a thimble or small cap of WD40. Or you can drill a tiny hole in the plug and fill the plug area with oil and let it seep through the hole for a day or so.

No need to disassemble the speedo. But its not difficult and if you do you can grease the odometer gears while in there.

[Art B.]

Re: '61 Speedometer needle bouncing

I can see, perhaps, three issues that would lead to excessive speedo needle bounce.

(1) The inner cable is running dry in the outer sheath creating too much friction. The corrolary is lack of proper lube resulted in the outer sheath becoming abbraded and you've got loose strands inside that are trying to 'wrap' around the inner cable. All the fresh lube in the world isn't going to fix that situation now...

(2) Due to lack of cable lube, the drive end of the speedo cable has 'rounded' and it's now slipping. Drive cable ends were square in shape and slid nicely into their mating drive components with a slight interference fit. The solution is to pull the original inner cable and replace it with a fresh one available at any local auto parts store as a speedometer cable repair kit available in various 'cut to fit' size increments.

(3) The speedo head in the speedometer needs to be serviced. Speedo repair shops clean and freshly lubricate the internal components and the good shops have test/exercise machines to check calibration, set the air gap between the magnetic drive and driven components as well as re-magnetize the speedo's drive component...

Jack: I pulled the cable out this morning and it appeared dry. I cleaned it up and lubricated it well. After driving a few miles the bounce is gone. Getting at the cable at both the transmission end and the speedo end is a bit difficult (I forgot which end the cable comes out).
Thanks for your comprehensive posts. I have gotten good answers from you every time I had a problem. Have you ever considered writing a book on C1 troubleshooting? I'm serious.

[Jack H.]

Re: '61 Speedometer needle bouncing

Hey, Art, it's my PLEASURE! I'm not always right, but sometimes even a blind squirrel finds nuts...

[Donald B.]

Re: '61 Speedometer needle bouncing

I have the same situation with my '62. So what end of the cable slides out - transmission or speedo?

Thanks

[Art B.]

Re: '61 Speedometer needle bouncing

Don: It slides out of the speedo end, which makes it easier than crawling under the car (I wish I had a lift). You may want to spread a cover over your carpet and seats when you do this as the cable can be black and dirty. It also helps when putting the lube in. After I cleaned the cable, I coated it with AC General Purpose Lubricant as I slid it back into the casing. I was surprised that the cable had almost no lube on it when I took it out.