56 Thunderbird Speedometer

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GAR64

Senior Member
Getting ready to take a look at an issue with a 56 Tbird speedo. Apparently, it is very noisy and jumps around. I was told they tried replacing the cable but that did not fix the problem. If lubrication and/or the cable is not the issue, what should I look at? Have not had one apart before but was hoping there may be a simpler fix than taking out the whole unit. May not get to it before Spring, but thought I would see what the common issues may be. Just how difficult is the removal? Thanks for any advice you may have.


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Could the problem possibly be the right angle adapter that is at the transmission and the cable hooks into that? Speedometers are usually pretty much trouble free.
There's a couple questions at the Thunderbird web sites. (see thunderbirdforum.com)


One regarding the right angle adapter on '56 Bird. (pricey to replace).
One regarding a speedometer on a '64. O this post I referenced a couple articles on how speedometers operate.


Personally I would suspect the right angle adapter if you have already changed the cable.
 
Noise from the head and jumping around are classic symptoms of dry or worn bushings in the speedometer head. Fords of the era are well known for the problem.
 
The hardest part is turning yourself into a 25 year old contortionist, the rest is easy. :D

Disconnect a battery cable first. Round up some masking tape and a marker for labeling wires and things before you detach them. A packing blanket to put on the floor will be more comfortable to lay on. An LED or CFL worklight under the dash will help you see without burning your head.

There are 4 nuts on studs that hold the speedo cluster pod to the dash.
Unscrew the ring nut that holds the speedo cable in place and label & disconnect the Fuel & Temp gauge wiring and dash lights as needed.

If you're doing more work under the dash than an R & R on the speedo, you may want to consider removing the seat for more room to lay in the car.

I'd be more specific about the cluster itself if I'd had mine out yet. It's still on the to-do list.
 

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When you get it out, take a close look at the wiring you disconnected. If the car's original, there’s a good chance the insulation is brittle and might crack. Tape up as necessary if a rewire isn’t in the program.

I could still get under there when I was 40, but at 69 I’d be pulling the seat first.
 
miker98038 said:
... If the car's original, there’s a good chance the insulation is brittle and might crack. Tape up as necessary if a rewire isn’t in the program.
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Be as careful as possible when moving wires around to avoid damaging the old insulation or breaking wires off of their terminals.
When you're done and reconnecting the battery there should not be any small (or large) sparks when first touching the battery cable to the battery terminal.

There are no fuses in the yellow main power wires under the dash, only some small thermal circuit breakers with exposed terminal lugs.
One of the metal jacketed heater or air vent cables may be touching a circuit breaker terminal, or other wires may have been dislodged and are grounding out. Find and fix before continuing with anything else. Have a fire extinguisher handy.
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GAR64 said:
Apparently, it is very noisy and jumps around.
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The symptoms make it sound exactly what I have experienced with my '55 speedometers (both of them). Usually, if you remove the speedo mechanism from the instrument cluster and clean it, then apply new lubrication, it will work like brand new again. To lubricate the rear bushing, pull out the felt plug at the top of the housing near where the speedo cable screws in. put a few drops of 3-in-1 oil down that hole and put the plug back in.
I had both my speedo's out several times. Years ago I made a color coded wiring diagram showing which wires go to which terminals on the instrument cluster. I kept that diagram in a storage envelope with other car related repair diagrams and info and I pull that diagram out every time I need to re-install a speedo. It has been used many times now.
After removing the four keepers under the dash that hold the instrument cluster, I get up and sit in the front seat with a terry-cloth nestled over the steering column to rest the instrument cluster upon it long enough to remove all the wires off the back while sitting in the seat.
 
In the event that you clean, lube and re-install the speedo, and it still does not act right, there are several pro's you can send it to for rebuilding but they are very expensive.
After having repaired the one out of my car several times (over a period of many decades), there was nothing more I could do for it, so I sent it off to be rebuilt first week of December. Here it is February 5th and I still don't have it back yet. The guy said they took a weeks vacation during the holidays first time ever. I don't disparage the guy for taking a week off. He said he's in a major backlog.
I think that most folks around here might recommend Bobs Speedometer. I had him rebuild a '55 fuel sending unit many years ago and it is still working good. But he is very expensive. They all are. I recommend trying to get a maximum turn around timeframe, look at their website for guarantee of quality workmanship before selecting any of the rebuilders.
This guy I am dealing with is not very good at communicating either. No phone-calls or e-mails from him. I called several times (worried that he might have shipped it and maybe it got lost in shipment). Couple weeks after receiving no reply's, I called again and he actually answered the phone. He said it wasn't ready to ship yet, maybe in a week. I asked him to send me an e-mail with tracking number when he ships it. That was more than two weeks ago.
 
dmsfrr said:
The hardest part is turning yourself into a 25 year old contortionist, the rest is easy. :D
Click to expand...

Well, I guess that depends. I'm 63 yrs old and still doing it the same way I did it the first time which was around 1984.
Most folks recommend taking out the front seat. I would never do that because as soon as I remove the four keepers under the dash, the next thing I want to do is sit in the front seat to pull out the instrument cluster and start removing the wires off the back.
But, I'm a shorter fellow, never stood more than 5'-6" tall and I could always have my back laying on the drivers side floor with my feet up on the seat. The last two times I did it, I didn't even need to adjust the seat back at all.
To me, the hardest part of the job is when you are ready to re-install the instrument cluster keepers. Many times they little washer that goes under wiring-harness hooks falls before you can get the nut started. Then you got to adjust your position to feel around the bottom of the dash for that washer. It happens every time.
 
I little trick I learned when helping a friend with his 57 Bird. Get a milk crate or other crate that is about the same height as the door sill. Put it up against the sill. Helps you lay your back straighter and makes it easier to get at stuff under the dash. Naturally, put the seat as far back as you can.
 
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