A while ago I replaced my tach cable and installed lubed with some lithium grease. I noticed yesterday that my tach makes a squeaky noise and the needle was doing the cable-bounce-conga (if you know what I mean). So, I pulled the cable off the distributor end and it feels fine. Plus, my tach is making an "ooot-ooot-ooot" squeaky noise that does not sound good.

My question is, is this time to yank out the tach (please say no) or do I just need some lubrication at the back of the tach (if I can get up there)?

I have a sinking feeling it's yank-the-tach time. cr@p. Last time (to replace bulbs and get the dash console out) I had to drop the steering column, and that was with no engine and rag joint attached. Any tips for getting the dash console out without touching the steering column?

Cheers

S.

 

What distributor do you have? If MSD I may know the problem.

 

Also, your distributor needs to be 'clocked' correctly relative to the engine. If the cable makes too much of a bend just after the connection to the distributor you'll have problems and go through cables.

 

Hey guys - thanks for the replies. Fully aware of having my tach clocke correctly and it is - I have a nice smooth arced curve in my cable. As stated, the noise comes from my tachometer, but I think I will spin it with a drill and see if I can hear the noise. Spinning it by hand does not work.

I do have an MSD distributor, but as mentioned above, have it clocked correctly, unless you know something additional that I don't?

Any other ideas? It was running fine for 400 miles, and this noise just started. I'll take a photo and post in the next few days so you can see how the cable lies.

 

I have the same exact problem in my '73 (I'm also using an MSD distributor) - I figure, same as you, that I'm going to have to pull the tach and have it serviced.

 

It's not the tach so relieve yourself there. I just had this problem two months ago. When you purchase the MSD distributor it comes with a brass adapter for the end of the cable that goes into the drive gear. What has happened is that being an aftermarket part it does not fit the end of the cable very well and what's happening is that it has now lengthend the inside cable and it's binding up inside itself. What you hear is the cable rubbing against the outside housing. What I had to do to correct this is take a flat file and lightly remove some of the metal on the cable itself so that the brass adapter will fit all the way down. I just lightly filed all 4 sides of the cable end.

 

I have a '73 with a MSD Pro Billet Corvette tach drive distributor. I have the same issue. I'll try what Mick has suggested and see what happens. I'm a little concerned that if I make the "square" a smaller "square" I run the risk of rounding off the edges as it is driven by the tach gear.

 

The end of the cable is square shaped so with the flat file only make a few passes on all four sides that way you dont risk distorting the cable shape. You may still need a little grease to pursuade that adapter on to it. The cable should go inside that adapter at least a half of an inch (give or take a little) until if hits the stud that is sticking out of it that guides it into the drive gear on the distributor.

 

Well, I gotta tell you that the comments from yourself (Mick 72) and others is reassuring. I suppose you are saying that the cable is slightly too long for the MSD adapter? I guess this noise could happen after a few hundred miles? I'll certainly give it a go this weekend. If all the others (08vycpe) could please let me know how it goes, and I will do the same.

Cheers lads!

 

What's actually wrong is that the hole for the cable in the adapter is "too small" for the cable itself. You will not be filing the end of the cable but the "shape" of the cable. Imagine trying to fit a 15mm bolt into a 9/16 size hole. They are very close in size but there is just enough difference to cause issues. When you attach the adapter to the cable it does not sit all the way down on the cable. Thus creating the problem of the cable being "too long". The adapter if not set all the way on the cable adds about 1/4" of length to the cable causing it to bind inside the cable housing.

 

Well, after playing around with the cable this weekend, this is what I found. The cable end fits perfectly into the adapter, but you got me thinking about whether the cable was just slightly too long and causing some binding at the tach end. So, I slipped a washer over the cable housing end to space it out slightly from the distributor and the noise (fingers crossed) is gone and didn't return after a 50 mile drive....

Thanks for the ideas. Let's see how long it goes for until problems develop again...

 

I don't think you will have any problems. From my personal experience the adapter fit on the cable fine but only about 1/8" maybe 1/4". It needs to fit on there at least 1/2 or a full inch. You can take the cable and hold it beside the adapter and the cable should stop inside the adapter where the little guide stud is on the adapter. What I did was marked the cable beside the adapter then worked on it until the mark was flush with the bottom of the adapter. Check the photo but the cable should stop at that stud. Again that's just what I did.

 

Thanks Mick, I get what you're saying. I still had at least 1/2" of cable in the adapter. I'll see how it goes and post back if there's issues. I also had unclipped the cable from the back of the tach when the noise started as I didn't want to cause any unnecessary damage (did that one-handed too - not a bad effort!) and had reattached. That also may have reseated the tach end of the cable into the tach a little better.

Time will tell...

 

If I have one complaint about this forum it is that people post problems and ask for help but for the most part don't report back to the post to let others know what the successful fix was. I'm not speaking of this post though.

The info in this post helped me fix my problem. Thanks to Mick, Spindog and others for their input.


Today I removed the tach cable from the tach and filed down the surfaces of the square a bit. That was not my problem as the square tach cable fit all the way down into the brass tube with a square hole that fits into the MSD tach drive without removing any material. As I filed the wire of the inner drive cable began to unwrap causing the cable to no longer fit into the close fitting square hole. The more I worked on it the worse it got. Even burring the ends was causing the cable wire to unwind.

Siince based on what I read in this post it seems the root cause is that the cable is slightly too long and this causes the cable to push on the internals of the tach itself causing the squeak, squeak and the bouncing needle. With that in mind I used my trusty Dremell to grind down the end of the tach cable about 3/16". This still left me with plenty of engagement (1/2" or so) into the distributor. It worked, no more noise and no more bouncing needle.

For those of you who are thinking about sending your tach out for repair or buying a new one, try the suggestions in this post first. It might save you a few hundred dollars and a lot of work.

 

08vycpe, great to see you respond. I have always been a firm believer in posting back results - heck, that's how we all learn, right?

Since I did the extra spacing on my tach, it has been behaving itself, and I have now racked up another 100 miles or so since. I wonder whether you also have a newer replacement cable since mine had the same specifics as yours; cable 'fibers' pressed into the square drive shape. This is why I was against filing or altering mine - the washer trick worked real well.

Gotta thank Mick72 for the original seed of thought that led to the fix.



edit: the original cables have a 1" metal end that would allow the filing trick that Mick 72 suggested - newer replacements seem to have the cable fibers pressed into a square shape that would explain the issue you had when filing down (and what stopped me contemplating such a modification).

 

I'm just glad that any info I give can help someone else. This forum has been one of the best things for me working on mine. I think like everyone else, I try to do as much as I can to both (1) learn and (2) SAVE MONEY, but in the end it's great to have a place where you can throw out a problem or idea and find someone that has been through the same thing. I don't know about you guys but my town is full of Mustangs and camaros so trying to find a knowledgable Corvette guy is slim. Although I have found two in my area which both are very good so if any of you guys in the Greenville Spartanburg SC need to take your cars somewhere just let me know. Thanks again

 

I was looking at the spare tach cable I have and noticed that there is a swagged brass ferral at the tach end of the cable with about 7/8" of cable downstream of the ferral that fits inside the tach. That may be too much cable for the tach. If I was replacing the cable and had access to both ends I think I would remove some of the 7/8" at the tach end as well as removing some material from the distributor end or using the washer trick.