Speedometer Trouble - FJ40 (1 Viewer)

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Jul 10, 2020
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Location
Colorado
Looking for expert help. I have never had this issue before. My ‘69 FJ40 spends winter in a heated garage except for the few sunny days without winter crud on the streets. Started it up yesterday after a two month rest and the speedometer was registering 50 mph when I was going 25 and the needle went well beyond 100 mph when I was going 45 or 50 mph. I could hear the speedometer making a whirring noise as the needle approached 100 mph. I tried to go as slow as possible with everyone running me off the road. I did not want to break anything. I was successful but I still have the same issue but to a slightly lesser extent (20 = 40; 40 = 65 on the speedometer. Only other hint I can provide is that I washed road crud off of the exterior and undercarriage in early January before storing the FJ in the heated garage (45 degrees). Any and all thoughts on what may have caused my speedo to go nuts while resting would be appreciated.
 
It would have to be something up in the speedometer/dash cluster - anything under the hood or on the transmission wouldn't do that behavior.

Most mechanical speedometer needles are a bit like a floating mechanism - I'm guessing some crud (a bug? corrosion?) got in between the disk the cable spins and the disk that's linked to the needle. But just a guess - I haven't dug at the guts of the 40 dash.



inside-a-mechanical-speedometer.png
 
Usually a simple fix. If your ‘69 is similar to my ‘75, this is what I would do.

1) Disconect the battery! Important.
2)) Remove the cable from the T-Case and at the speedo cluster.
3) Remove the cable from its sheath
4) Clean it up, lube it up & reinstall.

Should get you going, if not…buy a new cable from @Cuiseroutfitters.

Be CERTAIN to disconnect the battery before you start.
 
@Relot76

Same thing happened to my 72. New speedo cable from Cruiser outfitters, greased cable with special cable lube, cleaned and regressed speedometer gears. Speedometer needle finally broke off last year from all of the intermittent shaking. The speedo needle shaking and erroneously high speed was 100 percent correlated to cold weather on my truck

Hope your result is better than mine.
 
@JVZii is the only speedo expert I know. Give him a holler.




devo
Thanks @devo.

The cable can cause the speedometer to jump around for sure. Especially if it is sticking a little bit. However from what @Relot76 noted namely the whirring sound. This is likely a speedometer problem. The older screw in shaft and bushing get worn out and I think they start to vibrate which then makes the needle act erratic usually ending in the needle spinning all the way around and breaking off.

I would certainly try a cable, its much cheaper than a speedometer and it may be needed anyway. Otherwise a new speedometer may be needed. I may have one if you find you need one.

Jack
 
Thanks @devo.

The cable can cause the speedometer to jump around for sure. Especially if it is sticking a little bit. However from what @Relot76 noted namely the whirring sound. This is likely a speedometer problem. The older screw in shaft and bushing get worn out and I think they start to vibrate which then makes the needle act erratic usually ending in the needle spinning all the way around and breaking off.

I would certainly try a cable, its much cheaper than a speedometer and it may be needed anyway. Otherwise a new speedometer may be needed. I may have one if you find you need one.

Jack
Thanks @devo and Jack! You are correct Jack. Before I could get the speedometer cable disconnected, the needle spun off of the speedometer. It is now laying between the glass and the speedometer plate. I cannot tell if it is broken or spun off. There is a shaft on the needle. I will take a photo and maybe you can tell if the needle is broken. I cannot dig into the repair right now, but I will keep your contact if that is ok with you for later work. I have an extra speedometer when I thought my original '69 was broken a few years ago, but a new cable seemed to fix my problem until yesterday. The extra speedo I have is from a later FJ40 model (maybe 72-74) since it has the newer connector, while mine has the pin with the screw cap that goes into the back of the speedo. Maybe I can use some parts from it to fix mine.
IMG_3227.JPG
 
The pin from the speedometer mechanism is broke off in the needle. I see it sticking out

I hate to be a downer but likely you won't be able to use any later model speedometer parts with a metal body speedometer like you have here.

Beautifully painted cluster BTW.
 
The pin from the speedometer mechanism is broke off in the needle. I see it sticking out

I hate to be a downer but likely you won't be able to use any later model speedometer parts with a metal body speedometer like you have here.

Beautifully painted cluster BTW.
I really appreciate your help. The cluster is original. It has never been touched. That is why I am disappointed that the speedo broke. Is it possible to fix the speedometer or get it repaired by someone with the knowledge like you have? My FJ40 is an 8/68 - model year 1969. I am going to attach photos of the extra speedometer I have. It was misrepresented as fitting a 1969 FJ40 but obviously it is a later model. This one works based on me spinning it manually. I also have the full instrument cluster that housed the speedometer. Maybe you can recognize the model years and someone else can use it. Again, I really appreciate your help and advice on what can be done with my now broken '69 speedometer.
IMG_3230.JPG
IMG_3231.JPG
IMG_3232.JPG


IMG_3228.JPG
 
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Drop me a pm.

I have a couple of extras that are good and we can workout a trade for your spare. That dude is red. 😁

If you want, You can send your bad speedometer to me It comes out the back so you don't have to damage that great front bezel. I will reuse the face, needle and odometer. Then you will be back in business with the same visible parts and mileage.

Thanks
Jack.
 
JVZii,
I have the identical issue with my 70 FJ, with the “screaming speedo”. I have pulled the cable, cleaned, inspected, lubed and reinstalled. No difference.

I then pulled the speedo and confirmed the loose, rattle-pieces in the speedo assembly. Needle is still attached.

Are you up for doing another speedo surgery? Miles shown is 24k+

If so, please DM your mailing address and details.

Thanks, Mark
 
JVZii,
I have the identical issue with my 70 FJ, with the “screaming speedo”. I have pulled the cable, cleaned, inspected, lubed and reinstalled. No difference.

I then pulled the speedo and confirmed the loose, rattle-pieces in the speedo assembly. Needle is still attached.

Are you up for doing another speedo surgery? Miles shown is 24k+

If so, please DM your mailing address and details.

Thanks, Mark
Btw, here are pics.
12A6747A-7578-46ED-BA36-C44C782D30DE.jpeg
9ECFCF06-FAE4-45C4-95CC-EC0FD6EC0AE5.jpeg
9ECFCF06-FAE4-45C4-95CC-EC0FD6EC0AE5.jpeg
 
Usually a simple fix. If your ‘69 is similar to my ‘75, this is what I would do.

1) Disconect the battery! Important.
2)) Remove the cable from the T-Case and at the speedo cluster.
3) Remove the cable from its sheath
4) Clean it up, lube it up & reinstall.

Should get you going, if not…buy a new cable from @Cuiseroutfitters.

Be CERTAIN to disconnect the battery before you start.
Hey. I'm curious...why do you say to disconnect the battery before removing the speedometer cable at the t-case? Is it grounded to the transfer case?
 
^^^

Electrical issue…not at the T Case end, but instead at the speedo end.
When you tilt the cluster to remove the cable from the speedo cluster you have a very high probability of shorting the amp meter to the metal parts of the dash.
If this happens you will ruin your amp meter & be dead in the water. Disconnect the battery 1st and you are good to maneuver the speedo cluster.
 
^^^

Electrical issue…not at the T Case end, but instead at the speedo end.
When you tilt the cluster to remove the cable from the speedo cluster you have a very high probability of shorting the amp meter to the metal parts of the dash.
If this happens you will ruin your amp meter & be dead in the water. Disconnect the battery 1st and you are good to maneuver the speedo cluster.
Thanks! So, if the battery wasn't disconnected and the speedo cable / gear was removed from the t-case and reconnected, it shouldn't be able to short anything out right? I replaced my speedo cable o-ring at the t-case when I was changing fluids. I don't recall if I disconnected the battery or not. Ever since then, my speedometer hasn't worked (it's possible I just didn't re-insert it properly, but it's pretty straight forward). After a week or two of driving, I developed a weird electrical issue where the 12V ignition wire is somehow grounded and my truck hasn't run since. I'm trying to think of a possible scenario where these two things are related.

....or, just coincidence.
 
Yes, if you only disconnected the cable from the T Case and did not mess with the speedo cluster, then you did not cause an electrical short.

The cable itself is mechanical & not affected by anything electrical. The electrical part is when you accidentally touch metal (the dash) to the backside of the amp meter. If you did not open up the dash, you are good.
 

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