Hey guys-

I get this question at least a hundred times a year.

Yesterday I scanned in the old 68 Delco cable and case book so I pulled this out of it. This is the original GM instructions for lubrication on speedo and tach cables and this may end some of the debate about what is the correct method to use.

The lube is not available, but this lube was similar to the graphite based lubes available at most parts houses.

Willcox


18243

 

Your continuing contributions to the Forum are very much appreciated! But I wish to introduce one small point of further debate . The GM method is no doubt effective but I have one as well.

For many years I have protected many moving parts (door/trunk locks, etc.) of my cars with graphite. That lubrication is very effective during our very cold winters. I have seen -45*F where even antifreeze can turn into a mush. But my locks still worked.

So when it came to installing the new tach cable last week I turned to graphite again. (BTW, thanks for getting that to me in good time.) It is a "dry" lube where the graphite is applied to the part via a volatile carrying agent that disappears within seconds leaving the part free of oil and grease, thus no wicking into the speedo or tach head is possible. The pic shows an inner cable being treated, this the old cable for demonstration purposes. It is very slippery but dry. On installation the new cable was flawless for several hours of driving yesterday: not a hint of a flicker. So just a thought.

All that aside there is another important message in your post. Don't just slap a new one on without prep. There are no instructions on these products re pre-installation requirements and I suspect that many go on "cold."



*Edit* - Someone asked me via PM where can you buy graphite lube. Most automotive stores will have it. I have the spray can and drops versions. They are basically the same.

 

Paul,

I could not agree more about the graphite! I've used it for years! Grease is the horrible for speedo/tach cables simply due to the fact that it ends up in the head! I've rebuilt speedometers here that were packed with grease and this as GM indicates above is fatal.

It stops the operation of the speed cup and it will also cause the first worm bushing to wear out prematurely.


Willcox

 

Hi Wilcox and Paul,
Thanks very much for posting the GM instruction sheet, picture and info. This really is one of the FAQs.
Regards,
Alan

 

is it the same procedure for the tach drive?

and does the cable just pull out at the dizzy and then slide back in?

 

I wish but I'm afraid no. The inner pulls out at the tach head end. I had to pull the tach/speedo dash out to get it out. I do not know what GM was thinking. It was a miserable experience with a lot of blood lost on the initial attempt from underneath until you get brutal but gentle on the dash pad from on top. Those who suggested smaller hands from underneath..................???? Especially with cross braces on a convertible. You can't get into that promised land from below. Even with a mirror and a light you can't even see the back of the tach. Even from the top I lost more blood on the firewall grommet installation (distributor cover brackets). Hydrogen peroxide does a nice job on preventing blood poisoning. I've recovered. Molson Canadian has vitamin B12 and other cleansing agents to shore up your immune system.

http://forums.corvetteforum.com/c3-t...-1974-a-2.html

 

I kind of have to agree with Paul about not being able to reach the tach cable from underneath. I had my column out of the car, the lower trim removed, the A/C duct removed while hanging upside down on the floor. There was no way I could reach the tach cable.

Maybe the idea of removing the A piller trim and the top dash pad would give me access.

 

That is a good idea on removing the right dash pad and the upper. I have directions on the site for doing this. The only issue is the risk in cracking the upper pad.

Once the upper pad is removed you can access the wires, the cables and just about everything behind the LH pad.

I don’t know how Victor gets to the cable but he manages to do this without pulling the pads. . . .Then again I have twenty years on him too!

Willcox

 

I did that last year when I replaced the speakers and heater core. I was lucky and did not hear that $400.00 CRACK!! I did not want to tempt the Corvette gods again.

In this pic you can see the passenger side brace used to stiffen the birdcage on convertibles. There are two more on the driver's side plus A/C ducts. As I noted we could not even see the tach from below with a mirror and light much less get a hand in there to grab the clip. Perhaps a coupe without A/C is different?

My Brother, who helped me, just finished a complete dash refurb on his 1979 without A/C. He says that the tach is in full view from underneath. So I guess accessibility depends on year, coupe or convertible, and accessories.

BTW, note the upper/left edge of the gauge bezel: the infamous SNAP. It was replaced.

 

I was thinking there are 4 on the drivers side but I only see 3 in this pic but your point is made " its very tight ". Note the speedo cable ( one on left) going over the top of the brace. It must go over the top or you will put the cable and the speedo head in a bind. If the cable goes UNDER the brace it will also change the angle of the face of the speedometer.

 

Thanks for the pic! Very interesting. I have never gone that far on the driver's side.

You can see the brace just above the gas pedal and below the tach cable. I think that was the gotch'a factor for me.

 

Just an obtuse follow-up on this thread. Graphite is just basically carbon particles and thus is non-combustible. Exhaust manifolds are cast iron and carbon will bond to that material. For purists, a set of rusty exhaust manifolds is the creme-de-la-creme. After all when the car was delivered to the dealer that's the way they were. Along with brake rotors and other components (lot rot). In fact that applies today even with new cars.

I have never liked that rusty "original" look. I realize that there are exhaust manifold treatments out there and I am sure they are fine products. But my solution is graphite (can shown above). I spray the rattle can mix into the plastic top and apply to manifolds with a Q-Tip. Is it NCRS right/correct? No. But it is better than rust. It will burn to a whiteish colour in the middle with time but heck for $5.00 a can and a five-minute application you are good for five years. Typically I do that job twice in a driving season.

Just another tip from the OFC (Old Farts Club).

 

My speedometer cable has started buzzing, so I want to lubricate it. I found this thread from a search, and I can get the graphite lubricant (even though Paul's pictures have expired, I'm pretty sure I know what he is talking about). What I don't understand is that the picture shows the cable in someone's hand. Do I have to take the cable completely out to lubricate it? Can I remove one end or the other and lubricate that way?

 

Do brand new cables need to be lubricated? I just purchased a new tach cable and never though about lubricating it....

 

If it came in a plastic bag and the inside of the bag had signs of a lubricant smeared in it, then, no, it would not need to be lubed. Otherwise, it should be. If you received it "dry", you don't think that your vendor considered sending a tube of the 'correct' lube with the cable when you bought it....do you?

 

You put the graphite on a rag and pull the inner cable through it wiping off excess as you pull it through.

 

In the old days when vendors made up their cables they might send you one dry.. but I don't think anyone sells what we called "Cable and Casing" dry these days. So my answer is no.. if you purchased a new cable with case it will be ready to go.

 

 

Phew.... Because to be honest, I had no intentions of taking it back out, especially for as hard as it was to do the first time.. For as little as I drive it, I would just wait 5 years for it to break again..

 

So I have to remove the cable and casing from the car?