The speedometer on my 66 Roadster stopped working. Does anybody have some possible causes? Is it possible to unscrew the speedo at the transmission and pull out the cable? Or do I have to unscrew it under the dash (very tough to do) and replace the entire cable assembly? Has anyone had their speedometer stop working if so what did you do to fix it. Thanks any suggestions will be appreciated!

 

The nylon drive gear in the transmission tail has been known to strip from time to time. You can pull that end of the cable and test the cable and speedo with a drill. The gear can be replaced by pulling the gear retainer and gear. Its one bolt and a small lock tab, and then they pull straight out. If you have to replace the cable its a lot easier when the instrument cluster is out.

 

Jim,

You guys are making me want to get into the gauge restoration business. If your cable and trans gear gear are good (?) it is possible that you have a needle shaft separated from the speedcup. There are other problems too but that would be my first guess. Does your trip meter and odometer work?

 

Avispa has good info. Also, it's possible the cable just snapped, but not too likely. The cable has to come out from the head end. That means the cluster should be removed. Many threads here about doing that. After the cluster is out that will allow you to clean out the cable housing. By using a semi flexable long wire with a small piece of rag pinched on the end, and soaked with WD-40 pretend you are rodding out a gun barrel. A lot of junk may well be clogging it up. Follow the tips found in archived post for finishing details Dennis

 

Guess what I am saying is that if the odometer and trip meter work it is in probably the speedcup/needle shaft and not in the transmision.

 

Yes Avispa I will take a look at the transmission end of the cable.I have never replaced that nylon gear in the tranny. Doe s Zip or long island corvette carry the nylon gear to replace the old one if it is stripped? I am not looking forward on removing the instrument cluster to get to the speedometer. Something easy for once would be nice!

 

tgtexas02 recommendation is the best place to start, IMHO. If the odometers are working, you don't have a cable/transmission gear problem. Saves a lot of effort.

 

If LI Corvette or Zip doesn't have 'em, one of the other vendors will for sure. It's a common item. tgtexas is correct. If the odometer is working, then the cable system is good from end to end and the trouble may be elsewhere in the speedo. You sure don't need to do the electric drill test to figure that out. OTOH, the odometer may not be working, even if the cable system is good. There are plenty of threads on here about non-working odometers. The odometer drive gear inside the speedometer head is failure prone in these cars.

 

Trying to keep you from tearing too many things apart hoping it fixes the problem. If your speedo needle and meters are not working you most likely have a broken cable and/or bad trans gear. Internal issues with the speedo gauge could have contributed to this condition such as a partially seizing magnetic rotor shaft bushing or worn and binding "worm gears" or your cable housing got extremely dirty. So, if you find the trans gear stripped and/or you have a broken cable...you might still have other problems in the gauge.

 

It is a 50+ year old car. I would just bite the bullet and remove it and send it out to be rebuilt. JMO. You will be better off in the long run. ( of course assuming it is not a simple cable problem )

 

I took the speedo cable that connects to the transmission and put the cable inside a drill and spun it and the speedo in the interior works! Ya! I removed the 7/16 bolt that held the tab up against the gear that the cable end screws on. I tried the wedge a flat end screwdriver blade to coax it out but no go. Do you have any suggestions on how to pull out the gear? Thanks, Jim

 

Finally got it out...I screwed the old cable housing to the interal drive gear and pulled and it came off...Going to clean it up and order a new plastic gear/o-ring/internal seal from ZIP...Has anyone done this before? Just wondering how to remove the internal seal and replace it with a new one.

 

Jim,
Did you find any physical damage to the gear? I have never seen, or heard of, the plastic gear stripping the metal gear in the transmission.

On my 67 the gear was worn out on the shaft where the upper inner seal had worn a slight groove in the plastic and the seal itself was rock hard. I bought a new "bullet with inner seal installed from Chevy, but had to purchase a new o-ring outer seal for the bullet as Chevy doesn't include that. A new gear was about $10, the bullet about $25 and an o-ring from work was nada.
The failure of the inner seal and wear on the gear shaft allowed the trans gear lube to migrate up the cable and into the speedometer requiring a removal and rebuiild/restoration/calibration. The person that did this also did it to the tach and recommended a new speedo cable. After two repop replacements i had one made to GM factory specs Not repop cheap chinese pieces of crap.
Forum rules prohibit me from giving out the great company that made my perfect replacement. Contact me offline for who did the good work.
Decency deters me from citing the vendor of the cheap crap from china.

The only problem I am having now is getting used to both the speedo and tach needles being rock steady and not bouncing after 35 years.

Don

 

Great advice! Neither my speedo nor odometer are working. I installed a new cable, during restoration, and even tested it with a drill, so I'm thinking my tranny gear is bad.

 

Jim,

Were you able to do this without lifting the body or tranny any? Any help is appreciated!

This is one of my next projects to accomplish. I assume I need to remove the gear first before ordering a new one since there are different gears with different teeth.

 

Boy oh boy, I'm reading this and thinking yeah I have those same issues. Mine is a 63, 340 hp 4 speed convertible and my speedo and odometer do not work either. I'm out in Az and have heard of Zip but never used them for anything. Has anyone used Corvette Central or is Zip the best?

Doug

 

Don, could you provide names of the rebuild services and cable supplier? thanks, Steve (I am having problems with my '67)

 

That was 3 years ago, possible you won't get a response from Don.

 

For gauge repairs I use Corvette Specialties of MD West.

https://www.csofmdwest.com/product/1...d-speedometer/

I just put one in a friend of mine's 64 last week. He ordered it Monday it was here in Vegas Tuesday. He's sending the broken one to them on a buy back.

They will also fix yours. Wait time is 6-8 weeks

 

I'm still here.
For the correct perfectly fitting tach or speedometer cable contact:

John RULLO
Deluxe Speedometer Repair
2330 S. Kalamath St. Unit A
Denver, CO 80223

1(888) 907-6505

https://deluxespeedometer.com

Fair pricing and quick turn around and delivery.

Don