Bouncing Speedo needle

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Joined
Aug 8, 2014
Messages
374
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6
Location
New York
My Car
1973 Q code Mac 1
Is there anyway to tell based on symptoms if the Speedo needle bouncing is caused by the gear in the tranny, the cable or the Speedo itself or does one start with the easiest thing first and move on from there? In my case the Speedo needle is stable up to about 50 mph and then swings or bounces as the speed increases. I had a motorcycle where the plastic pick up gear was worn but that Speedo would just read low. Almost Cost 600 bucks to have a mechanic needlessly replace an instrument cluster before I just changed that little gear!

Sent from my SM-G935V using Tapatalk

 
Most likely the cable with the bouncing needle. Cables are cheap and fairly easy to replace.

The inop speedo til 25 could be the speedo itself.
Thanks. It's annoying and I would like to fix it. Now for the next questions. I think read years ago the 73s have a two peice cable. Does this make it tougher to get to and or can I use a one piece. Also can i just lean forward the dash bezel surrounding the Speedo to get to the cable on the back of the Speedo or do i need to drop the steering column etc. If it matters I have a tilt wheel so I might be able to get some clearance. Thanks again.
Sent from my SM-G935V using Tapatalk

 
Most likely the cable with the bouncing needle. Cables are cheap and fairly easy to replace.

The inop speedo til 25 could be the speedo itself.
Thanks.  It's annoying and I would like to fix it.  Now for the next questions. I think read years ago the 73s have a two peice cable.  Does this make it tougher to get to and or can I use a one piece.   Also can i just lean forward the dash bezel surrounding the Speedo to get to the cable on the back of the Speedo or do i need to drop the steering column etc.   If it matters I have a tilt wheel so I might be able to get some clearance.  Thanks again.

Sent from my SM-G935V using Tapatalk
With a tilt column it is no problem to get the whole thing out, did that a few times! 

Concerning the speedo cable I dunno - I have only found cables until 1972 - but no cables for 351C 4Vs with 4-speed manual and no 1973... :huh:

 
Most likely the cable with the bouncing needle. Cables are cheap and fairly easy to replace.

The inop speedo til 25 could be the speedo itself.
Thanks.  It's annoying and I would like to fix it.  Now for the next questions. I think read years ago the 73s have a two peice cable.  Does this make it tougher to get to and or can I use a one piece.   Also can i just lean forward the dash bezel surrounding the Speedo to get to the cable on the back of the Speedo or do i need to drop the steering column etc.   If it matters I have a tilt wheel so I might be able to get some clearance.  Thanks again.

Sent from my SM-G935V using Tapatalk
With a tilt column it is no problem to get the whole thing out, did that a few times! 

Concerning the speedo cable I dunno - I have only found cables until 1972 - but no cables for 351C 4Vs with 4-speed manual and no 1973... :huh:

I think that is what I found too!  Thank you for the info - are there any tips in terms of getting the dash out?  How much to I have to remove?  I am considering how many little items I will break along the way to fixing the bouncing speedo!

I have to go in there anyway as the one dashlight I have out is of course on the speedo.  The PO said he converted to LED but it does not look like that is the case anyway.  

Where are you in Germany?  I am heading from Berlin To Vienna next summer.  My kid is singing in a choir in five cities.  Cant wait.
 
Thanks.  It's annoying and I would like to fix it.  Now for the next questions. I think read years ago the 73s have a two peice cable.  Does this make it tougher to get to and or can I use a one piece.   Also can i just lean forward the dash bezel surrounding the Speedo to get to the cable on the back of the Speedo or do i need to drop the steering column etc.   If it matters I have a tilt wheel so I might be able to get some clearance.  Thanks again.

Sent from my SM-G935V using Tapatalk
With a tilt column it is no problem to get the whole thing out, did that a few times! 

Concerning the speedo cable I dunno - I have only found cables until 1972 - but no cables for 351C 4Vs with 4-speed manual and no 1973... :huh:

I think that is what I found too!  Thank you for the info - are there any tips in terms of getting the dash out?  How much to I have to remove?  I am considering how many little items I will break along the way to fixing the bouncing speedo!

I have to go in there anyway as the one dashlight I have out is of course on the speedo.  The PO said he converted to LED but it does not look like that is the case anyway.  

Where are you in Germany?  I am heading from Berlin To Vienna next summer.  My kid is singing in a choir in five cities.  Cant wait.
Hmmm, you don't have to do much! There are some screws in the cluster panel and some that are holding the cluster, thats all. Here is a vid, up to 3:45 there you go



After that you have to get out the plug of the circuit board and the speedo cable which you have to unclip - here are some suggestions:

https://www.7173mustangs.com/thread-how-to-remove-cluster

I am located in the south of Germany, near Stuttgart. Great that you accompany your kid to such a outstanding trip! Is it a famous choir? In which cities they will be?

 
With a tilt column it is no problem to get the whole thing out, did that a few times! 

Concerning the speedo cable I dunno - I have only found cables until 1972 - but no cables for 351C 4Vs with 4-speed manual and no 1973... :huh:

I think that is what I found too!  Thank you for the info - are there any tips in terms of getting the dash out?  How much to I have to remove?  I am considering how many little items I will break along the way to fixing the bouncing speedo!

I have to go in there anyway as the one dashlight I have out is of course on the speedo.  The PO said he converted to LED but it does not look like that is the case anyway.  

Where are you in Germany?  I am heading from Berlin To Vienna next summer.  My kid is singing in a choir in five cities.  Cant wait.
Hmmm, you don't have to do much! There are some screws in the cluster panel and some that are holding the cluster, thats all. Here is a vid, up to 3:45 there you go

thanks Tim.  I was poking around and just found that video!  Now I am left thinking.....while I am in there should I be upgrading to LED's considering they are even on sale right now!  If I don't feel like digging into the other areas with lighting right now can I just do these LED's on the tach, speedo and gas gauge and move to the other areas when I get to them?  In other words will that mess up the circuit mixing and matching bulbs?

I am somewhat concerned as looking at the video there are actually about 7 lightbulbs on the speedo and in my case none of them are working.  Unless they all blew out over time I might have a wiring issue there?

So far I know we are going to Berlin (concert will be in the Kaiser Wilhelm Memorial Church), Dresden, onto Prague and then Vienna.  I am very happy to be going with her.  The last time I was in Berlin there was still a wall and Checkpoint Charlie was in full operation!

 
It doesn't matter if you only do the cluster bulbs and not the other ones in the cars. But there are special recommendations like to do not the turn signal indicators because of the original relay circuit and the brightness of the LEDs in your face. But you could get a speacial relay for that. Other than that there are no concerns against it... Seems to be perhaps a short in your circuit or some other problems. Check your clusters printed circuit first and its plug, your headlight switch (turn it from left to right a few times), then...  ;) 

Yes, the wall has gone since a few years - at least the one out of bricks... ;) Is your daughter in a Gospel Choir?

 
One thing that can make the speedo bounce is that someone put an oil or grease on the cable thinking that would lube it, NOT SO. You need to get a tube of graphite lube for speedo cables. It does not get stiff in cold weather like a regular lube will. Since the cable is made to flex it is like a long spring and will wind itself up until it can spin thus making the needle jump. Gear might have issue I do not know.

Not sure if you can remove the cable from under the car or not but would try first and clean it and add the graphite. If there is oil or grease you will have to pull instrument cluster so you can spray brake cleaner down the cable housing and then blow it out good. Bee sure it is out of transmission when doing. 

Here is link to what I am talking about it is also to be used in locks for same reason temp does not affect the function.

https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60/ref=sr_1_2?ie=UTF8&qid=1508331755&sr=8-2&keywords=graphite+lubricant

 
It doesn't matter if you only do the cluster bulbs and not the other ones in the cars. But there are special recommendations like to do not the turn signal indicators because of the original relay circuit and the brightness of the LEDs in your face. But you could get a speacial relay for that. Other than that there are no concerns against it... Seems to be perhaps a short in your circuit or some other problems. Check your clusters printed circuit first and its plug, your headlight switch (turn it from left to right a few times), then...  ;) 

Yes, the wall has gone since a few years - at least the one out of bricks... ;) Is your daughter in a Gospel Choir?

Yup.  I'll just do the bulbs in the kit.  My switch seems fine.  My lights otherwise are as bright as I would expect for the year!  I do have another switch coming just to try but probably not necessary.  

Going into East Germany back then was a little strange but now I am sure it is different although there are still "walls".

I would not say its a Gospel Choir per se.  There is also going to be an orchestra performing as well.  She has traveled a fair amount already but I think this trip will be a game changer for her.  I am truly more excited about going somewhere then I have been in a long while.  I will be on the same itinerary but not really with her at most times. I want her to have some freedom.  I might rent a motorcycle and trail the trip for a few days on that.
 
One thing that can make the speedo bounce is that someone put an oil or grease on the cable thinking that would lube it, NOT SO. You need to get a tube of graphite lube for speedo cables. It does not get stiff in cold weather like a regular lube will. Since the cable is made to flex it is like a long spring and will wind itself up until it can spin thus making the needle jump. Gear might have issue I do not know.

Not sure if you can remove the cable from under the car or not but would try first and clean it and add the graphite. If there is oil or grease you will have to pull instrument cluster so you can spray brake cleaner down the cable housing and then blow it out good. Bee sure it is out of transmission when doing. 

Here is link to what I am talking about it is also to be used in locks for same reason temp does not affect the function.

https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60/ref=sr_1_2?ie=UTF8&qid=1508331755&sr=8-2&keywords=graphite+lubricant

Thanks David.  Always good advice from you!  I am thinking that if I am going to pull it from the cluster anyway and remove it from the transmission side as well it might just be time for a replacement cable although I like fixing what is there when possible.  Good point about the temp affecting lube.  
 
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