Speedometer
Thread Starter
Instructor
Joined: Jan 2007
Posts: 115
Likes: 0
From: Jasper Indiana
Speedometer
When I go cruising in my 79, the speedometer sometimes tends to bounce up and down. For instance, when i am cruising at 30 mph, the speedometer will bounce down to around 25 and up to about 40. It does this at all speeds but doesn't happen all the time. Can anyone help me figure out why this is happening?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
The speedo cable itself is binding in the sheathing. I have done this before but not on a Vette and getting behind the gauges is a pain in the butt.
Basically you need access to the speedometer end of the cable. The end of it, that key, will pull out pulling the cable with it out of the sheath.
Don't pull it all the way out...maybe half way. Then, coat it with graphite powder or lithium powder, and slide it back in.
Then, pull it out and push it in a few times to get that powder coating all the way down to the trans.
Button everything back up and you'll be good to go.
Basically you need access to the speedometer end of the cable. The end of it, that key, will pull out pulling the cable with it out of the sheath.
Don't pull it all the way out...maybe half way. Then, coat it with graphite powder or lithium powder, and slide it back in.
Then, pull it out and push it in a few times to get that powder coating all the way down to the trans.
Button everything back up and you'll be good to go.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Suggest pull core completely from outer housing ... clean & blow off/out both ... inspect core for any fraying ... lube core w/ moly grease or moly paste ... reinstall.
Burning Brakes
Joined: Feb 2005
Posts: 847
Likes: 4
From: Atlanta
This has probable been asked before and may be obvious (I've been tinkering with my 82 for a couple of years now so have much, much to learn)......can you remove the speedo cable at the transmission end and pull it out? Probably designed so that can't happen; keep it securely in the speedo.
Mark
Mark
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
This has probable been asked before and may be obvious (I've been tinkering with my 82 for a couple of years now so have much, much to learn)......can you remove the speedo cable at the transmission end and pull it out? Probably designed so that can't happen; keep it securely in the speedo.
Mark
Mark
No you can't pull it through from the bottom. There is a key on the end of the cable that slides into the back of the speedo and that's too big to fit through the sheath.
Melting Slicks
Joined: Mar 2006
Posts: 3,341
Likes: 7
From: Connecticut
A cable greaser is a great little tool to have.
Read the instructions for an idea of how they work.
http://bigcoe.com/universal.html
Read the instructions for an idea of how they work.
http://bigcoe.com/universal.html
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Pro
Joined: Aug 2007
Posts: 706
Likes: 30
From: Pitman NJ
On my car, the lower cable went bad. Basically the transducer starts to go bad, and puts more tension on the lower cable until it eventually breaks.
I replaced it with one single cable. It's not necessary to take the dash apart to get it off. I was able to kneel down outside of car, and slide my left hand up under the dash.. Follow the cable up to the speedo, and push a little metel tab, and it releases the cable.
Pull it out into the engine bay, and the gommit in the fire wall will come with it. Put the gommit on the new cable, and fish back in the hold. Reach behind and just push the new cable onto the speedo, it just 'snaps' on. The other end screws onto the trans.
It took me about an hour to do it, if I had to do it again, it would take me about 15 minutes.
I replaced it with one single cable. It's not necessary to take the dash apart to get it off. I was able to kneel down outside of car, and slide my left hand up under the dash.. Follow the cable up to the speedo, and push a little metel tab, and it releases the cable.
Pull it out into the engine bay, and the gommit in the fire wall will come with it. Put the gommit on the new cable, and fish back in the hold. Reach behind and just push the new cable onto the speedo, it just 'snaps' on. The other end screws onto the trans.
It took me about an hour to do it, if I had to do it again, it would take me about 15 minutes.
Racer
Joined: Apr 2007
Posts: 413
Likes: 4
From: Marshall MI
Replace the cable
$14.xx at Autzone, probably less elsewhere. Just did the same on my '75 yesterday. Cheaper than a cable greaser tool and will probably last well beyond your interest in the car. Took me about 20 minutes to replace and I am larger than average and less talented than average.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
$14.xx at Autzone, probably less elsewhere. Just did the same on my '75 yesterday. Cheaper than a cable greaser tool and will probably last well beyond your interest in the car. Took me about 20 minutes to replace and I am larger than average and less talented than average.
Melting Slicks
Joined: Nov 2000
Posts: 2,507
Likes: 114
From: St. Louis Mo
I bought the fitting to lube the cable but it didnt last long. I replaced the cable myself (79 4 speed) in about 20 minutes., and I am not a mechanic. Took the front seat out which made it a lot easier.LT
Racer
Joined: Apr 2007
Posts: 413
Likes: 4
From: Marshall MI
Cable replacement
Best to put the front wheels on ramps or stands. That way you can get to the fitting on the transmission. Unscrew the ring at the transmission. Then get up under the dash at the rear of the speedo, where the cable goes in, there is a tab you can push down and pull the cable jacket out. The cable and jacket then can be pulled out through the firewall grommet (be careful if bubba has used the grommet to route a million wires, like on mine...)
Installation is the reverse of the above.
Installation is the reverse of the above.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Best to put the front wheels on ramps or stands. That way you can get to the fitting on the transmission. Unscrew the ring at the transmission. Then get up under the dash at the rear of the speedo, where the cable goes in, there is a tab you can push down and pull the cable jacket out. The cable and jacket then can be pulled out through the firewall grommet (be careful if bubba has used the grommet to route a million wires, like on mine...)
Installation is the reverse of the above.
Installation is the reverse of the above.
