[chevyguy1969]

speedometer (spelling) on my 79 is swinging 60 to 70 mph at steady hiway speed what do i need to look at to fix this.

 

[vette427-sbc]

i belive that there is some kind of spring that keeps the needle tight when accelerating. when the spring goes bad it takes less acceleration to get the needle to swing farther than it should. if you want to take the speedo apart you could try to replace the spring but i think you might be better off geting a rebuilt or new one
fyi- it gets worse over time, my 55 chevy swings to 90 mph when accelerating to 40

 

[big2bird]

speedometer (spelling) on my 79 is swinging 60 to 70 mph at steady hiway speed what do i need to look at to fix this.

graese the cable with "red grease" Bet you have cruise control, right?

 

[TimAT]

Lube the cables like Big2Bird says. If it's still jumpy, find someone to rebuild your cruise control transducer.

:cheers:

 

[chevyguy1969]

thsnks for response guys

the car was equiped with cruise control but i don't think it made it back in after the engine change. i don't see any thing extra hooked up to throttle linkage. looks like choke and gas pedal. the cable looks secure on the back of the gauge how does tthat meatal retainer come off?

 

[big2bird]

the car was equiped with cruise control but i don't think it made it back in after the engine change. i don't see any thing extra hooked up to throttle linkage. looks like choke and gas pedal. the cable looks secure on the back of the gauge how does tthat meatal retainer come off?

It doesn't come off. It's a spring style captive clip. Just push it toward the front, and pull the cable out at the same time. It is easier with two people. Hold the clip in, while someone pulls the cable from the engine compartment.
You can also pull the cable out from underneath the car. Undo it from the tranny tailshaft, and pull it out there. Clean well before lubing.:thumbsup:

 

[chevyguy1969]

question

wikkthe internal cable pull all the way out from the transmission. and hard is it to fish it back in. this would seem like the better way to do this instead of trying to work up under the dash. i guess i need to read my manul some more too. thanks for the help guys

 

[big2bird]

wikkthe internal cable pull all the way out from the transmission. and hard is it to fish it back in. this would seem like the better way to do this instead of trying to work up under the dash. i guess i need to read my manul some more too. thanks for the help guys

Not a problem.

 

[Eddie 70]

the car was equiped with cruise control but i don't think it made it back in after the engine change. i don't see any thing extra hooked up to throttle linkage. looks like choke and gas pedal. the cable looks secure on the back of the gauge how does tthat meatal retainer come off?

The transducer will be just outside the firewall. The cable from the speedo will be about 18 inches long and will go into the transducer. If the transducer is still there, disconnect the cable going back to the speedo. Use a drill motor and turn the cable. Have a helper watch the speedo and see if it runs smoothly. IIRC you have to run the drill in reverse.

 

[big2bird]

The transducer will be just outside the firewall. The cable from the speedo will be about 18 inches long and will go into the transducer. If the transducer is still there, disconnect the cable going back to the speedo. Use a drill motor and turn the cable. Have a helper watch the speedo and see if it runs smoothly. IIRC you have to run the drill in reverse.

Yep. If still there, they gum up and make the needle bounce.:thumbsup:

 

[chevyguy1969]

it getting better

pulled the speedo cable out today it is about 5 feet long it was dry but clean i wasn't sure how much grease to put on it so i went on the light side.took the car out for a two hour test drive (it was a nice day in Airzona and it was alot better it only jumped around a few times think i will pull it back out and put more grease on it ---unless someone here says not to thanks again for the advice you just can't find this info in a manuel. :cheers: :thumbsup: :thumbsup:

 

[chevyguy1969]

helpful tip

here is a tip that worked great for me i repulled the speedo cable and really greased her up. then i stood there with greasy cable looking at my freshly cleaned interior (HMMMMM) i had a plastic bag from my lastest runn to the parts store i cioled the cable up inside the bag being careful not to kink it and fished into the cable housing straight from the bag presto cable stayed clean as did the interior. just thought i throw this out there in case someone else ran into this have a great day.:thumbsup: artyon:

 

[jotape650]

well yesterday i bypassd the cruise control because it wasnt working and the PO had messed up all the cables. but like the above mentioned the speedometer seems to be a bit jumpy and mark above the speed im really traveling at.! This means new Speedo right? thanks dudes!:buhbye:

 

[Elduderino]

Remove the drivers side a/c duct. Reach underneath the dash and push the lilttle tab in that holds the speedo cabel to the rear of the speedo and pull it out a little to free it up, then disconnect the other end of the upper cable from the transducer and pull out the inner cable shaft. Grease that little sucker up as much as you can and fish it back in there, the reconnect everything,

Youll be good to go!