andycw

Hello All,

I've got the lower dash etc out while replacing the wiring harness and thought I'd ask advice on silencing noise that emanates from either the speedo or tachometer. What do you suggest. It isn't always present but sometimes after driving for a little while it starts making noise. Will lubrication in the cables with white grease cause any problems? What about the tach and speedo hookups? This is for a 72.

Thanks,

andy

69 Chevy

white grease? Graphite oil will never turn brown and harden.

jim-81

Well if it's the speedo cable, then I would suggest replacing it. Even if you are not sure, it is a fairly cheap and easy task. The cable is about $25 and is not too bad to replace, there are many threads here on it...

Jim

Alan 71

Hi Andy,
Its good to see your post!
While driving you should be able to isolate whether it's the speedo or tach by taking your foot off the gas and taking the car out of gear and letting it coast. If the noise quickly diminishes, or stops... it's the tach.
Sometimes what you hear in the car coming from the tach is actually the tach drive gear in the distributor that the tach cable hooks to. Have you checked to see if it's worn?
Good Luck!
Regards,
Alan

73Corvette

A week or two ago my wife and I went on a short cruise and I thought OMG....the throw out bearing is going out. The wife listened real close and we decided it wasn't coming from the shifter console but from the dash....the kicker was it would do it when I revved the engine. So I know it was the Tach cable.... here's what it looks like attached to the distributor...
I moved the coil and the distributor shield to make it easier to get at...
I sprayed a little wd-40 to get it freed.....and then filled the little bowl with marvel mystery oil and put my mouth over it and blew on it till the bowl was empty forcing the oil in the sheath....did that about 3 times and it is as smooth as silk........

69 Chevy

I just read a thread the other day where it was said the left dash had to be disassembled because neither tach or speedo cables won't go in the heads by themselves. Apparently you, like me, never had that problem.

BTW, a universal speedo cable can be had at Autozone for $4, then cut down to fit the tach.

08vycpe

I too had a noisy tach cable. Through the advise of a fellow CF member I was able to solve the problem.

There is a ferrel swaged to the cable at the tach end. The amount of cable downstream of this ferrel was a bit too long. I am told the aftermarket new tach cables share this issue.

I solved the problem by grinding about .040 from the end of the cable with my Dremmel. I learned from experience that as I ground the end of the cable the spiral wire began to unwind. I had a hard time getting the cable to fit back into the opening. So I would suggest before grinding anything from the end that you "tin" the end with solder as you would do with electrical wire and then file the last 1/2" square again.

I was thinking of sending the tach out for a rebuild that would have been very expensive. Grinding a bit off the end has worked for 3 years so far. You can do the same at the distributor end.

Another CF member used a washer as a spacer and said it worked for him.

As far as lube goes, only use graphite lube. The kind you would use in a lock for the tumblers. The fluid carries the graphite and then evaporates leaving only the graphite as a lube. Remove the cable from the sheath, spray it with graphite and reinsert it back into the sheath.

andycw

Thanks all for the advice. I decided since the dash etc is out that Id just go ahead and replace the cables with new ones as mentioned above. Im going to keep the old ones on hand.

azza2u

Just keep in mind that it might not be the cable. Replaced mine but noise was still there when dash went back together. Pulled dash and tach out again and tested turning the tach input with a drill and it was the actual tach mechanism binding up a bit causing the noise.

0Willcox Corvette

Andy.. just a bit of advice when going back together.

Do not hook the tach cable to the distributor or the speedo cable to the tranny until after you have the dash back in the car. Doing it this way will allow you to connect both with the dash pulled away vs. trying to connect them with the pad installed.

The same goes for those pulling a left hand dash pad. If you unhook both before you pull the left pad, you can simply reach in behind the pad when you pull it away...

Willcox

Now for those of you wondering why you should never put any regular grease on the cable. The cable is reverse wound and grease applied to the cable will be forced upward in to the Tach/Speedo head. This puts oil on the oilyte bushing in the first worm and magnet which collects dirt from the magnetic field. It will cause premature failure of the gauge. Powder graphite, or special Cable lube only..

Below is the page from the original Gauge Calibraion manual.

andycw

Thanks Mr. Ernie for the installation info and the info on why not to use grease. Also thanks to Aussa2u for the idea about the drill. I shall check the tach with that before I intsall everything.

Mr. Alan, wish I had tried that before I had everything out of the car. Always good to read your posts.

andy

08vycpe

Keep in mind if you replace the cable with a new one it may still be too long and you will have the same problem. Shortening the cable at both ends a little is well worth the effort.