Speedometer Gremlins..........

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pastortom1

pastortom1

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A while back, I had my original 67 Cuda speedo rebuilt and calibrated by Redline (If I remember right).......They seemed to do a good job......Put it in the car with the original cable and it worked fine.....BUT, I drove the car VERY little.

After 3 or 4 years of 200 miles per/year if it was lucky, I brought it to Florida to begin the detailing and rebuild. I hooked up the speedo with a new cable, and have had nothing but trouble ever since. It actually acts like an old worn out unit that's not accurate, squeaks and squawks and just generally goes nuts.

I've seen it before and have corrected a few, but this one has me pullin' out my hair for some reason.

I removed the dash and speedo today and cleaned everything up. Checked the unit, and found little to no problems with movement.....the magnet was OK and everything was free and working great......After a very light lube, she was near perfect. Hooked the cable back up for a test, and it simply jammed the needle.......I've seen cables too long before (no joke) that pressurized the drive-shaft of the unit so much that it froze the needle....sure enough, it seemed this was my problem. I carefully trimmed the length with a rotary sander, trimmed the width just a squeak to be sure it wasn't hanging up inside the cable socket, and it helped free up the movement somewhat.......BUT, still puts too much pressure into the shaft socket and drives the needle nuts.

With zero pressure against the cable socket on the back of the speedo, you can spin the unit to hearts content and get a nearly perfect working speedo. Insert the cable and begin to tighten just a little, and it starts to jam and run like crap. Right now, I have the cable threads (where it screws onto the back of the unit) nearly all the way off. The speedo works, but not right......close, but no cigar.

Funny thing is that I have a spare speedo, and it does the same thing......

Specific question concerning the cable.......I can't remember from past experiences.......When a new cable is attached to the transmission and tightened down, is the inner cable then able to be "pulled out" from the dash end? I thought that they were "fixed" at that point and couldn't be pulled out from the outer casing......This one CAN be pulled.....I pulled it over an inch before stopping and thought the other end broke........BUT it still works.......but not right.....Just ain't right......Erratic.......not accurate........I was thinking that if that cable is "traveling" inside the casing (in and out, so to speak...even small amounts) then it would change the pressure exerted to the drive shaft of the speedo......and again, when you do that, the speedo will just not work properly.

If any of you guys have experience monkeying with these internals or cables and have had similar problems, chime in here and lets chew on it a little.......

This one is drivin' me a little nuts.........

I'm wondering if I should try another new cable and see what happens......Maybe this one is just not right in some way.......
 
if its the same type of speedo cable as mine it is a 2 piece dont know what the little cylinder thing is for but it should be on the firewall along the cable route....maybe somethings up with that.
 
hmmm.....maybe something is inside the cable causing it to bind up...its a long shot but ive had it happen on my old 280z
 
I don't believe the trouble is in the cable at all
 
Well based on what I've laid out here, what do you think it is then?

The speedo works nearly perfectly when spun manually (with a power drill) and no "inward" pressure on the speedo shaft.......

Seems to me that something is afoot when the cable is attached, even loosely. That's when the trouble starts..........
 
If the sheathe isn't routed to the instrument properly it can put side pressure on the cable. Or the end of the cable may be bent.
And yes you can yank the cable right out at the instrument end.
Getting it push back in can be a chore. There is a nearly 90 degree turn in the sheathe under the drivers seat. The cable doesn't like to go around that turn. I just take the trans end apart too and straighten the turn, flush the sheathe and lube with white lithium grease.
 
Well, the end is A-OK......perfect fit to the socket....but as I said, it seems to be sticking out too far when it's back in it's sheath all the way......that's why I resorted to the trim......BUT, you can't trim it very far until you run into trouble with 'fraying' those little hairs the cable is wound from.......it's not like a spring steel, so it isn't so bad...but it will still come apart if you're not careful......

I'll check for sharp bends under the car too in the morning........
 
If you remove the cable you can remove a little length from the lower end also.
The sheathe can't have any sharp bends. Smooth curves are OK.
I've seen the cable wear almost through the sheathe in that turn under the drivers seat. Needle will twitch like crazy until the cable breaks. Only cure is replace the 2 piece assembly.
 
I checked the cable for sharper then normal bends and found none......You're right about the 90 degree under the seat, but it seems to be smooth, not too sharp.......I haven't lubed it any further but will probably try later today if another trim doesn't help.

Clarify for me what you mean by the "2 piece assembly".......I assume you mean the cable and sheath.......If not, I'm at a loss.......
 
pastortom1 said:
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Clarify for me what you mean by the "2 piece assembly".......I assume you mean the cable and sheath.......If not, I'm at a loss.......
Click to expand...
Yeah I said that because the aftermarket offers a universal cable to install with the original sheathe. That is a waste of time and money in my opinion.
Keep in mind that the cable spins inside the sheathe. There are conditions with the 2 parts that will cause the cable to travel. Easy way to find out is leave the speedo head disconnected and drive around the block. The cable should not run out of the sheathe.
Just in case it does, make sure that cable is not going to contact anything with power on it before you start.
 
Well, I installed the gauge cluster only (no bezel at all) so I could access the cable while driving........Don't attempt this at home you drips........

When I move the cable even by fractions, it has an effect on the way the speedo operates......Flutters, inaccuracy, etc........

This leads me to believe that the cable was VERY poorly lubed at the factory (or Chinese sweat shop, whichever is appropriate in this instance)......and is probably too long at the output as well.........

I'm wondering if I can find a REAL Mopar cable that might fit the bill instead of wasting any more time on this inferior piece of Chinese $%$#.......(pardon the expression). I must assume it's Chinese or some other worthless piece of work at this point.......I am SO sick of this junk finding it's way into classic cars....

I'm gonna start the search for the real thing I guess........If ANYONE might have a decent lead on a real one, let me know. :salut::salut:
 
I say mod the cable and if you're worried about fraying the cable, just solder up the end and smooth with a dremel, just like you would a wire to bind all of the threads together
 
Could shorten it still and finish the end, but it doesn't spin smoothly either.....Acts like an old dry piece of junk....SO, I'd have to take it off anyway to try a new lube job, put it back on, and hook it back up again just on the chance that it would be better..............

Not sure that's in the cards at this point..........
 
Used speedometer cable for a 67 will likely be well worn.
The collector nut holds the cable centered. When the nut is loose there's no doubt you could move it around and get weird noises.
 
RedFish said:
Used speedometer cable for a 67 will likely be well worn.
The collector nut holds the cable centered. When the nut is loose there's no doubt you could move it around and get weird noises.
Click to expand...

That being the case, then an overall length or travel inside the sheath is the likely culprit.

I guess I'll order the NOS from Mancini before they're gone..........they state only a few are left. They have a LONG collar too behind the nut that will help to keep dead center.......This cheap one is VERY short, nearly non-existent.
 
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