Speedometer jumping

[1969CoronetR/T]

I took my Coronet out of storage yesterday (and again today) since the roads are dry and it was 45 degrees outside. Cruised to the highway and opened it up. A Dodge Ram Big Horn edition tried to keep up, but the 440 blew the Ram away (I have A 2007 5.7L Durango with a heavily modified and ported engine). I noticed that my speedometer was jumping from 4 to 15 (x10) so I could not tell my speed. The road was fairly empty except for the Ram so I was not being an idiot unless the police were to see me and I could honestly say I have no idea how fast I was going to the officer. Would the fuel sending unit need replaced or are there speed sensors a 1969? Am I even close to guessing what the problem is with the speedometer?
Thanks

 

[69HEMICORONETR/TCONV]

It's either the speedometer gear , speedometer cable or speedometer it's self.

 

[rrunner]

Is this a std cluster or a rallye cluster. I have had a bunch of std clusters that when it was cold like low 50's or below, and that's not too often here, the speedo will bounce like you said. Don't know what causes it, but if it's what I've seen it's in the cluster.

 

[1969CoronetR/T]

I am new to 'B' bodies, so I have no idea abouth the rallye (round?) or standard. It is a rectangle with the 1 on the left and a 15 on the right (straight line). I am guessing it is a standard cluster. This is what mione looks like except the for the ungodly huge tach:

http://www.forbbodiesonly.com/moparforum/showthread.php?p=53796#post53796

Thanks again

 

[moparker]

Sometimes you can grease the end of the cable where it screws into the speedometer and that will help. Good luck.

 

[74sundance]

I've had this happen a few times.
Once the speedo cable's outer cover melted on the exhaust.
I had one that was ticking and I just shot some WD40 down the tube and it's been fine since.
And one Satellite I had the Cable was held in place by some tie wraps and routed badly causing the cable to rub on itself on the inside, I rerouted it and the ticking went away.

 

[1969CoronetR/T]

Thanks, I will try some grease and WD-40 and see if it clears up. Funny thing is that it only happens when I go about 50 or more.

 

[moparker]

I think you may need a new cable. Sounds familiar to me. I think my Scamp was like that.

 

[Patrick]

Over time the inside of the cable housing gets worn and makes the cable start to slip in the gear, which in turn wears the end of the cable causing it to snap turn in the housing making the speedometer needle jump. Ebay has cable and housing for about 30 bucks. Note you will have to reuse your fire wall grommet.

 

[Propwash]

Try changing out your speedo cable

 

[Meep-Meep]

If it's not the cable it's most likely the speedo itself. It's been my experience that the plastic bushings that support the needle movement wear out and the magnet rubs on the aluminum drum. I fixed the one in my 66 Belvedere by machining some new bushings but I got the spring too tight on reassembly so it reads slow - but no bouncing!

 

[dodge41969]

If the speedo bounces 5-30 m.p.h, it's the speedo cable, sometimes you can pull the inner cable out and grease it with some wheel bearing grease, just put a dab of grease on your fingers and feed it back into the housing, rotating the cable as you feed it in.
DO NOT use white lithium grease!, it's the worst,
or WD40 (it's a cutting oil, it dissipates quickly)
high speed bounce indicates the speedo head needs a repair,if it bounces severly followed by screeching sound, discconnect the cable at the head,or eventually it'll break the cable.

I used to work at "Redline Gauge works" www.redlinegaugeworks.com
they can handle any repair/resto you have ,including tach reapairs,clock quartz conversions,speedo repairs etc.
they even make speedo cables, the factory/aftermarkets were junk,basically they were made with a wire mesh coated in plastic,when the plastic gets hot enough (when too close to the exhaust) the plastic melts and seeps through the wire mesh, then that grabs the cable and breaks it.

anybody have any Gauge related questions feel free to send me a message.

 

[rrunner]

If it's not the cable it's most likely the speedo itself. It's been my experience that the plastic bushings that support the needle movement wear out and the magnet rubs on the aluminum drum. I fixed the one in my 66 Belvedere by machining some new bushings but I got the spring too tight on reassembly so it reads slow - but no bouncing!

That seems like what I've run into. I sometimes have heard a ding or ring sound, that must be when the magnet hits.

 

[1969CoronetR/T]

Now I know where the horrible screeching sound is from the speedometer, bur it usually makes the noise just before the bounce. I can hear a grinding noise from the left side of the dash and knew it was not the wheels or brakes. Thanks dodge41969 and everyone else for the insight.

 

[68ChargerAG]

One more note... they do make a special oil for speedo cables. You can find it at the auto store. I would try that before grease or WD-40. Grease might harden and make problem worse later on, and WD-40, like has already been said, would not be good for this application. Just my 2 cents.

 

[dodge41969]

One more note... they do make a special oil for speedo cables. You can find it at the auto store. I would try that before grease or WD-40. Grease might harden and make problem worse later on, and WD-40, like has already been said, would not be good for this application. Just my 2 cents.

The only time the grease would be a problem,is if you filled the cable housing with a grease gun!
Seriously I use a synthetic wheel bearing grease, your only putting grease on your finger tips, and lightly coating the cable as you feed it in, basically the cable is always spinning (like a wheel bearing) and I've noticed the lighter cable specific oils don't seem to last very long, kinda like sewing machine oil,
just think how fast that is cable spinning at 80 m.p.h.!

 

[dodge41969]

That seems like what I've run into. I sometimes have heard a ding or ring sound, that must be when the magnet hits.

That "ding" sound is the speed cup hitting the magnet,
either the magnet is wobbling on the shaft or the, upper jewel is worn,
too much play.

 

[PFG MOPAR]

Grindng sound ??

mine makes a loud grinding sound occasionally.
and says I'm doing 80 when I'm really only going about 50 ..?
When I stop and then go again, the sound usually stops.
Would lubricating the cable help or is it in the spedo itself?

Less then 30k on a 73 Satellite..

ixie:

Thanks,

Mike.