Tach Cable

[Rick Hammill]

I am having serious problems with my Tach cable. Last year I restored my Tach Drive Distributor, put all new components in. The problem was that the cross shaft where the cable goes in was all worn out and it seems to have taken its tool on the cable itself wearing down about a quarter inch of the cable. So the cable keeps sliping out of the new cross shaft because it seems too short.

Question: Can it replace the cable without replacing the whole housing and if so where can I purchase just the cable or will I have to purchase the cable and housing together?

Rick

[Patrick H.]

Re: Tach Cable

Rick,

I tried this, but the new cable was an inch or two longer than the old one. This meant it REALLY stuck out the end! You may be able to do this using a good condition used cable, but I don't think the currently available new cables come in the same length as our old ones. If so, I think Joe will let us know. Of course, a longer cable means my new one has even more of a curve/twist as it attaches to the distributor, but I'm not sure how to fix that unless I can find a shorter one again.

Replacing the entire cable is a lot more work than just the inner piece, so I fully understand why you'd like to do it this way. You replace the inner piece, though, from the dash side so it still isn't a totally uncomplicated procedure.

Patrick

[Rick Hammill]

Re: Tach Cable

Thanks Pat,

I will look for a used cable in Carlise this year!

Can you give me a rough procedure on how to get to and change the inner cable? I have been through the dash always on the right hand side of the car, but never messed with the speedometer or Tach side.

Rick

[Jeff M.]

Re: Tach Cable

been there done that, I have replaced the entire cable in a matter of a few minutes. Reach under the dash and feel for the tach cable. Go to the end and push in on a metal spring clamp while you pull on the tach cable. it is usually on the top side, it comes free very easy, from there you can follow it out the firewall side. Or buy the entire housing and cable and just use the cable of the new one. I think the catelogs sell a cut to fit replacement cable.

[Joe L.]

Re: Tach Cable

Rick------

The best solution to your problem is a very simple one. First, remove the inner drive shaft from the tachometer cable housing assembly. This does have to be done from the dash end, but regardless of what approach you take you're going to have to get under the dash. Second, take the tachometer driveshaft cable to a speedometer service shop in your area. Tell them that you want another one just like it except that you want the end longer (by the amount that is worn off your end). This will result in a tachometer driveshaft which is the perfect length for your particular application.

Lastly, lubricate the cable with speedomter cable lubricant and install it. You're done.

[David D.]

Re: Tach Cable

Jeff, Sounds like you haven't done one on a midyear, they do not use the spring clip, they are threaded. Dave

[Patrick H.]

Re: Tach Cable

Joe,

For those of us without any local speedo shop, does GM still make a tach drive cable the same length as any of our originals so that we can swap a new inner cable for our old broken ones?

Patrick

[Gary S.]

Re: Tach Cable

Patrick, we ordered a replacement tach cable for my buddies 73 from one of the catalog companies (I THINK Paragon) and tried to just pull the old cable out and replace it with the new cable. Way too long. We haven't found anyone carrying the correct length cable.

Gary

[Joe L.]

Re: Tach Cable

Patrick------

I don't think so. GM currently offers only 2 ways to go for 69-74 Corvettes. The first is a complete shaft and casing assembly. This assembly, GM #25032184, is 20.7" in total length. I believe that this differs a bit from the originals. You can use this one as a complete assembly, but I don't think that you can remove the shaft and use it with the original casing.

The second is a "cut-to-length" unit of GM #6477499. This shaft is 70" long. You cut it to the required length and stake on the tachometer drive end with a "staking tool" supplied with the part. Sometimes it holds for as long as a month or two. Best bet is to seek out a speedometer shop. You might even be able to call one in a distant city, tell them the length you need, and have them send it to you. Speedometer-Electric Service in Hayward, CA is one such source that I know can do it.

[Bryan M.]

Re: Tach Cable

Though not GM, I purhased a inner cable at the local auto part store. I believe it was in the HELP section. It comes with one end attached and the other end loose. The loose end is attached with a crimp tool that is provided. I matched the cable length to my original 68 frayed tach cable, cut, crimped,lubed and installed.
It's been working okay so far.
Bryan