Speedometer cable going bad?
 

So the speedometer on my 67 GMC started making some noise above about 35 mph a couple weeks ago. When it does this the needle starts wavering up & down, (usually up to about 50 or so) Well this morning on the way to work it really started getting loud and started flopping from 0-120 or so. I assume this is the speedometer cable going bad, correct? When it happened in other vehicles it just stopped working period. Never had one go nuts and start flopping around before. haha!

Re: Speedometer cable going bad?
 

If if the internal cable isn't frayed yet. Unhook behind the gauge. And put Lube down inside the cable. It has worked for me before. Good luck.

Re: Speedometer cable going bad?
 

The cable has one plastic end, and sometimes that breaks and then the speedometer stops working. It sounds like your cable is binding. You can pull it out, clean it, and lube it with white lithium grease and it will probably work for another 40+ years.

Re: Speedometer cable going bad?
 

Thanks guys, I'll see if some lithium grease will help. Can't hurt, that's for sure. I had it off when I changed the dash face out early this spring and it looked ok then. Of course it doesn't decide to do this until it's 5* outside... sigh...

Re: Speedometer cable going bad?
 

Seems like I read on this board that graphite works better..... but all I ever used was white lithium grease and it worked fine for me.

Re: Speedometer cable going bad?
 

If graphite gets wet it turns into a thick gummy mess. I wouldn't use it....

LockDoc

Re: Speedometer cable going bad?
 

^ Good to know.... thanks, Leon!

Re: Speedometer cable going bad?
 

Interesting tidbit I never knew....

Re: Speedometer cable going bad?
 

Just to be clear, the best way is to pull the entire cable out, clean it as well as you can, and then lube the entire cable lightly with white lithium grease. Just putting lube down the end of the cable may help for a while, but it's not the best solution.

Re: Speedometer cable going bad?
 

No problem. The reason I know is because I have disassembled many automotive door and trunk lock cylinders that had graphite used in them and they were really bad inside. It was like a thick paste, and in a few of them it had hardened into a semi-solid chunk....

LockDoc

Re: Speedometer cable going bad?
 

They actually do this worse in the cold - the cable binds more easily, I suppose due to what lube (or dirt?) that is in there thickening in the cold. Both of my K10's speedos worked fine in the summer and bounced more in the winter, although the current truck is much better overall.

If it were 70* tomorrow, I bet your speedometer would work perfectly again. ;)

Re: Speedometer cable going bad?
 

I pull the cable from behind the odometer, spray it with brake cleaner multiple times to get it clean. let it dry (just a few minutes) then put it in a gallon freezer Ziploc bag. Then I put in some white lithium grease and smear it around real well.

Then I put white lith grease into the hole of the speedo cable housing and try to push it as far as I can. If I have it in a gun, I wil place 8-10 pumps in there. Then I run the cable in and out about 30 times, making sure the first end in has fresh grease on it each time. (Trying to push the grease to the bottom end)

Then I push the cable in from the bag until it is all the way in. The Ziploc helps keep my hands and the interior of the truck clean.