Speedometer stopped working

[1979C20]

Just recently my speedometer started bouncing a lot and making a ticking noise. Then it stopped moving at all. I pulled the cablr off of the adapter on the tailshaft and the wires were frayed and everywhere. Is that the problem? Or is it likely that it is broken elsewhere? And how do I replace it? Checker had    cable for my truck, cable and housing, but it was only about 2 feet long and looked like it belongs from the back of the speedo to the just out the fire wall. My cable is in 3 segments. Trans to just about the start of the bellhousing, from there to the bottom of my firewall, and from there to my speedo. And help would be great. Its a 79 c20 with a 350 and sm465 4 soeed manual. Also, my speedo reads 50 when im driving 45. How could I adjust that? Thanks guys.

[beastie_3]

If you dont have cruise, you can get a one piece cable. Some shops can custom make one too, but one from a parts store will be cheaper.

[86Chevy3]

Yea I would say that's your problem, to replace it you need to disconnect both ends of it and pull it through your firewall, and to fix the false reading issue you need to change the plastic gear inside the tranny the the speedo is ran off of, they make different ones that are color coded and were designed for different applications and you can pick one up from just about any tranny shop, just tell them how it's off and what tranny it's goin in

[1979C20]

Okay. I'll check for that one piece when I get off of work. I do not have cruise. Manual everything. Tranny, throttle, clutch, windows, doors, lights. Erverthang. Except just recently I installed a keyless entry that I'm already having problems with. But I opened a different thread for that one. Thanks a lot guys.

[1979C20]

http://www.oreillyauto.com/site/c/detail/PIO0/CA3005.oap?keyword=speedometer+cable&pt=C0073&ppt=C0338
Would this be the one I'm looking for? I can only assume it is. I found the one checker showed me yesterday, and it was the "lower" section. But this one says 61" 4 speed manual.

[beastie_3]

When it is labeled lower and upper, I think its for the two piece setup for the cruise control.

[1979C20]

The one I posted a link to, it doesnt specify upper or lower. It says 61"s. So, that would be the one I need?

[beastie_3]

I think the one piece is 90 or so inches. Measure the old one and go from there.

[1979C20]

Good call, Can I pull the cable from the speedo and unthread it from the trans without worrying about leaks or anything? I dont want to pull it to measure it and have to put it back in then drive to checker then pull it back out to put the new one in. If I can pull it and drive to checker with it removed that would be awesome.

[ccz145a]

I would remove the piece then screw the connector back on just to keep the dirt out. It screws on like a garden hose.

[1979C20]

kay. I went home, pulled the cable, took it to checker. It was the 61" cable. I installed the new one, still doesnt work. :/ now what?

[Lt.Del]

could be the gear in the tranny stripped or moved or broke on the shaft.  Or could be the instrument cluster.  
Do a test, remove from trans and spin it with a drill (taped to the cable end) while someone looks at your guage to see the needle moves.  

[beastie_3]

Check to see if your speedo is working or not. Cut some of the black coating away to expose the inner cable. Hook it to a cordless drill and see if the speedo moves. That will let you know if its the speedo or the transmission.

[beastie_3]

USE THE OLD CABLE!

[1979C20]

Ill chrck it out tonight. Thanks guys.