I have to drop my passenger side exhaust downpipe which provide access to the speedo cable connection at the M20 trans. Is there any reason why I could not pull the cable out from that end to lubricate?

 

Someone will correct me if I'm wrong but I think there is a ferrule on the speedo end of the cable that stops the inner being removed from the transmission end.

 

Ahhh...that would be a problem. Thanks!

 

I wish there was an easy way to lubricate the cable. I had the dash removed to replace all of the gauges on my 68 convert and like a @@#$%^&*() dummy did not replace the speedo and tach cables. After the ordeal of getting the dash back in place with the almost non-flexible new wiring harness, I vowed never to take the dash apart ever again. So- I have learned to live with the speedometer that flutters at low speed and a tach that can't keep up with rapid rpm increase at WOT.

 

 

mechanical tach as well.

 

From the original Delco Calibration and cable book. We only use the graphite lube which should be available from your local parts store. The issue is that the cable is reverse wound and if you over-lubricate or use oil or regular grease it will pull this into the speedo head and cause first worm and magnet bushing failure.

Hope this helps.

 

My advice: Release the spring clip on the connector at the rear of the speedometer and pull the cable loose. Slowly pull the cable out of the sheath (it will be dirty so protect yourself and the car's interior when removing it). Wipe it down with a clean cloth and, if necessary, a volatile cleaner (carb cleaner, lacquer thinner, etc), then allow to completely dry. Put a squirt of DRY graphite powdered lube on another cloth and drag the lower 2/3 of the speedo cable thru the powdered lube. You do not need much on it.

NEVER put any petroleum-based lube on the speedo cable. It will wick-up the cable as it turns and worm its way into the speedo mechanism. NOT GOOD!

Reinstall the cable in the sheath and when it finds the end of travel, gently push the cable while turning it slowly so that the square end at the trans end will find its 'home' in the speedo drive gear shank. When seated, press the spring clip open and install the cable in the speedo head. If the cable still gives you trouble, the inside of the sheath is damaged and is dragging on the cable. You need to replace the entire cable.

 

Thanks Bill, I can’t go back to cable as my dist was changed. Thanks though, Steve

 

Be sure to save those original cable drive tachometers. I have a Factory K66 Transistorized Ignition system and it was working well. I removed it from my Corvette and had it rebuilt by Dave Fiedler (an Expert at T.I.) and then I vacuum bagged the parts and stored them away. My current distributor is a MSD Billet unit and it has the mechanical tech drive built into it.

Cable maintenance is important as I learned 50 plus years ago on motorcycles. It is absolutely amazing what some people tried to use for "cable lubrication". This subject has come up several times here on the Corvette Forum in the past months. After learning of the AC part#: ST-640 you might think it would be a no-brainer and just use the AC product. After reading on you will see it is a petroleum base product and they don't say much else. I might look into it before trying it on my cables

Others have spouted some ideas that might have value. Using the Dry Graphite Powder is probably the best as it doesn't have the drive to climb like a liquid would. Another suggestion was to make a mixture of White Lithium Grease with Dry Graphite in very small quantities and apply it to a pre-cleaned cable and housing. This mixture of grease and graphite makes a smooth black paste type mixture that is easy to handle. The mixture of grease and graphite is applied directly to the cable in small amounts and re-installed into a CLEAN and DRY cable Housing/sheath. Be sure to not put much of the lubricant within ~10" of the end that connects with the speedometer or tachometer. There is little one can do for a gummed up speedometer or tach so you must be careful to keep the lubricant from climbing up the cable into your instruments.

The proper lubrication of a cable is like many other projects on a Corvette, it takes a lot of time preparing the parts and cleaning them before you actually lubricate them. Just like a paint job or any other large project.

 

The speedo cable just has a spring clip on it at the speedo end and you might be able to reach up and release with the dash in place.The tack cable I did mine by pulling the dash forward to release it but couldn't get the new one in after taking the dashpad off dash forward so i ended up using a bore camera going through the firewall used the camera to line it up and was able to get it on.Having found that i could install it this way next time I'm sure i can release it the same way as the back of the tack head is in lnline with that hole.No need to remove anything inside the car.Most difficult part is getting the camera lined up and set in a position that you can see whats going on.

 

thank you!!!