Guys

I don't know if this is the right place to post this, but I have a question on the speedometer. This is sort of a dumb question, sorry.

The speedometer on my 74 Dart is wavering wildly above 55 mph, and the speedometer is noisy. I'm concerned something is going to break if I don't do something about it.

What is the problem here? The cable? The speedometer itself?
The service manual says no lubrication is needed. Is this true? What can I use? Motor oil? WD-40?

Also, I can't unplug the cable from the back of the speedometer.
There doesn't seem to be a clip or anything like that.

I'm sure this isn't that hard, but I'm not sure what to do.
Thanks.

I think you will find the cable is held in place with a large nut (for the lack of a better word) on the back of the speedometer. It will be unscrewed to remove the cable, once you remove the cable try to get some lube (light oil not too much) behind the end of the part that you will be able to turn.

Richard

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Part of Tyrde-Browne Racing

A nut? Shouldn't it just be a nylon connector with a tab on it that you push to release the cable from the speedo? If it is then it's probably old and brittle and will just break off if you try and remove it. Either way you're most likely going to need a new cable. If not, SlantSixDan has a writeup on here somewhere with good instructions on lubing the cable. It might be in the FAQ section, if not you'll have to search for it.

Mine used to wave all over the place and once I installed a new cable it worked fine again. Now I just have a slight rattle but I'm sure thats coming from the speedo itself.

No nut in '74; it is the plastic "squeeze top and pull to release" snap-on type. Might be enclosed in plastic anti-tamper box; consult service manual for how to open. Speedo head bearings are probably worn out; it wasn't really designed or built to last 35 years! Have it rebuilt. For most of 20 years I have used

DeLuxe Speedometer & Radio
1976 Bannock Street
Denver, CO, 80223
Ph# 303-629-6958

Fast, quality workmanship at reasonable prices.

But you may also find good speedo service locally.

Before you condemn speedo head, try servicing the cable.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yeah, I'm pretty sure it has the anti-tamper plastic sheath around it you're describing. I'l have to look at it again later. I couldn't see any way of releasing the cable last night.
Plus you know how much fun it is with your head on the floor of the car and you're underneath the steering wheel!

I took the speedometer cable out on a 75 once, and it just had a little clip you depressed, and the speedometer cable popped out of the speedometer. This one's not like that.

It's also really hard to get your fingers up in there to do this.
I'll try out your suggestions. Thanks again!

The '73-76 should be all the same...(actaully I think 1968-1976 uses the same plastic "cup" clipped to the back of the speedo...'67 being a 'hybrid year having the screw on nut speedo like the Pre-67 and the tranny end like the late trannies)...

The bad part is the clip is plastic and gets brittle then breaks when you are just to the point of pulling the cup off the speedo...

-D.Idiot

OK, it was incredibly easy.
The plastic clip was on the end of the speedometer cable itself, but it was up top where I couldn't see it, and I couldn't fit my fat fingers up in there to press down on it and pull at the same time.
Now on to lubricating the cable...
Thanks everyone.

OK. A little lube on the cable, and a little shot of WD-40 on the speedometer head from the back where the cable goes into it- and it's perfect!! Thanks everyone.

If it still wavers a lot, you may try disassembling the cluster to get the speedometer unit out. then gently blow out the accumulated crud from the speedo drive drum and follower. that may help. OR, like the man said: just get it overhauled by a good shop. (By the way they ususlly read wrong, usually read too fast from my experience with 1974-1976 Darts).

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

That's because the speedogear in the tranny wasn't changed when someone upgraded the tires on the car...

-D.Idiot

Ha ha- so funny you should mention this.
I was out driving on the interstate trying to figure out what speed "60" really is. It seems like if I go about 63 according to the speedometer, THEN I'm going about 60.

And yes it's because the car has radial tires on it but it would have originally had bias ply...

Understood, D.I. But also, in trying to figure out how to make the speedometer work right over the years, in 5 or 6 Darts/Valients, 1974-75-76, all with /6 and 904's and same rear ends, I've found they all use the same speedo gear in the trans. Seems the factory just said "close enough", whether they had 185-75R14, 195-75-R14, or 205-75-R14 tires. I actually bought the next size gear and tried it, but it was way off- worse then the stock gear. I don't remember now what the gear spec was- I could maybe find it in my files somewhere. In running family road trips using a couple of cars together, we found the speedometers read darn close to each other. At 70 mph actual, they read about 74, plus or minus 1, with any of the above tires. I think the circumference of the tires is almost exactly the same. I measured the 205's against the 195's at 30 psi, and they were about the same in my samples. (Tread wear is a variable.) I gave up on changing the gears. But if one was going to a racing tire or something exotic, then a gear change would be in order. Cheater's note: you can adjust the tension spring setting inside the speedometer, I've done it for a unit that read 8 mph off- got it down to just 3-4 mph off. Factory Quality. I try to take advantage of those radar read-out signs that give you your speed in wildly flashing lights (Speed limit 35, Your speed 57). I figure they must be pretty close.

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

does anyone have a picture of this clip where it goes into the speedometer? the sheath has come loose but i can't get the actual cable to come out of the speedometer, which is holding the cluster to where i just can't quite get it out. i'm going to replace the IVR with the nifty setup slantsixdan talked about in another thread, and while i've got the cluster out (when i ever get it out) i'm going to try to spiff up all the instrumentation and lube the cable.

The folks who make and sell replacement speedo cables say that after lubing the cable, wipe the lube off the top 6 inches. Otherwise, the lube can creep up the inner cable and gum up the speedo. Those last few inches are generally a pretty straight shot into the gauge and don't really need lubrication like the sections where the cable bends to get from the tranny to the gauge.

BC

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'64 Dart GT convertible, 64 Dart 170 2-door post sedan in faded blue and rust (the Az Dart) & a sixty THREE Dart 170 2-door post sedan in faded blue and rust. (future project)
Early Dart Disorder (EDD) is real, and I've got it!