Bouncing Speedo Cable

[68 ReNay]

my speedo's been bouncing once it hits 65mph for some time. i replaced the cable (cable and housing unit). now it bounces from 1-50mph then stops til 65 and starts bouncing again. so i graphite lubed the cable-no change, pulled out speedometer and put a couple drops of oil in the back of it-no change, i added more graphite oil to the cable-no change - but just today i began hearing the scraping sound (only noticed it at around 45mph). both 'holes' for the cable ends don't appear worn.

i'm at a loss. is it just the speedo itself that needs to be replaced? the speedo gear? it's so annoying to put on a new part and have the problem be worse!

it's a 68 1/2 ton. 350 small block with TH350.

any help is extremely appreciated!!!

[Sublvr72]

might be that the speedo gear in the trans has some chipped teeth. pull the cable at the tranny and open the gear housing and inspect it.

[chevy88]

I had this happen before, I replaced speedometer and problem solved. Good luck. But check gears in trans first like above post states.

[4tiresngas]

MIne was doing the same thing. It drove me crazy. I tried the graphite lube and even bought a new speedo cable. It was the actual speedometer

[mike16]

make sure the gears in the tranny are correct and in some applications there is a reduction unit that goes between the the tranny and the cable, otherwise it might be your speedo guage.carefull not to over lube the guage or use lube that becomes too viscous at lower temps.

[68 ReNay]

sorry so long in getting back.
Okay, so i finally shell out the money for a new speedometer and install it.
now the needle bounces up til about 42-43 MPH then steady up through 70+ MPH(i presume it's steady at even higher speeds for which i have not attempted)

Mike16, you said something about overlubing the gauge. i didn't lube it at all - didn't know i needed to. should i try this? and when i was checking the speedo gear i did notice what i presume to be another plastic 'gear' inside the case that was a similar color as my gear. i assume my gear turns with it. would this be the reduction unit?

my tranny has been rebuilt, but the bouncing needle existed before that. i just feel i'm at a total loss as to what's wrong; new cable and housing, graphite lubed, no kinks/sharp bends in line, speedo gear looks good, new speedo guage. each time i fix something, the needle bounces at a different speed.; first -no bounce til 65; then bounce to 50, stop til 65, then bounce again; now bounce til 43 then no bounce...

[6772owner]

Mine does the same thing (needle bounces) at lower speeds and then the same at higher speeds. Mine "seems" to be temperature sensitive, when I first start driving from "cold" the speedo needle does fine, then I will look down and its bouncing again. I have not tried replacing the speedo itself yet, but have done a new cable and speedo gears in the trans (700R4), hasnt helped me yet. I guess Ill try a new gauge and hope that does it...