Speedometer Cluster Disassembly Question (1 Viewer)

Joined
Apr 7, 2003
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637
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Mission Viejo, Ca
The speedometer on my '82 FJ40 started acting very erratic, jumping up to 80+ mph while only going about 40. It is not the plastic gear in the transfer case or cable. I moved the cluster to my '80 FJ40 and it did the same thing. I took it apart and everything looks and seems to work as it should but the part where the cable goes in feels a little gummed up when spinning it. I thought that I would just clean all gears, re-grease, and put it back together to see if that will solve the problem. However, I can't figure out how to remove the gear with the "bell" from the housing. Anyone know how to remove that piece? Also, any ideas on what the problem with the high indicated speeds would be? Thanks!

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TheHardWay

Ain't as easy as it looks
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Joined
Dec 29, 2013
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1,491
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Las Cruces, NM
That's about where I stopped with mine:
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After taking the pic, I removed the odometer. I had the same experience with the bouncing needle, and fixed it by pulling the speedo cable from the sheath, inspecting for kinks, cleaning the dried out lubricant, regreasing and reinstalling the cable. No problem now!
 
Joined
Apr 7, 2003
Messages
637
Location
Mission Viejo, Ca
I have a brand new oem cable so I can rule that out. It still bounced like crazy when I moved it over to my other 40 so I think the problem is somewhere in the cluster. The gears behind the “bell” look okay from what I can see. I am hoping it is something simple like gummed up gears...
 
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Joined
Jul 8, 2013
Messages
132
Location
Utah
Yikes! I have have been researching as well and it seems the magnetic cup is not serviceable. I took my 40 for a spin 2 days ago, the noise was unbearable and then AHH silence. UH OH! The needle is dangling straight down. :confused: Luck would have it, I found and scooped up a '77 instrument cluster today, my 40 is a '69. Now I must decide wether to attempt swapping in just the speedo assembly or the whole cluster. ? Step 1 will be snagging a clip style speedo cable. If anyone has done this in either way (total swap or just speedo) please feel free to post your library of links below.
I'll start Clusters, Gauges, Speedo & Odo meters - https://forum.ih8mud.com/threads/clusters-gauges-speedo-odo-meters.544543/

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Joined
Apr 7, 2003
Messages
637
Location
Mission Viejo, Ca
Just following up... I cleaned the gears behind the magnetic cup using electronics cleaner blasted in while spinning with a drill. A lot of dark crap came out with the fluid. I then greased the gears while spinning slowly with the drill to get the grease sucked back into the housing. The magnetic cup spun way easier after this. I cleaned and greased the remaining gears and put it all back together. During my test drive the speedometer worked perfectly until I first got over 65 mph and it then jumped to 85. After that initial jump it continued to work perfectly for the remainder of the drive so hopefully it will work for awhile before I have to deal with it again. After looking over everything and thinking about it some more I suspect the problem is likely with the speedometer spring and not the magnetic cup/gears. Maybe the spring is getting worn out after 366K miles?
 
Joined
Feb 25, 2011
Messages
108
Location
Sisters, Oregon
About 5 years ago my odometer quit working and I was able to remove all the odometer wheels changed the order of them, lubed them and reassemble . The speedometer must be lubed. I used singer sewing machine oil. Most bouncing speedometer needles can be attributed to lack of lube in the speedometer cable.
 
Joined
Jul 5, 2020
Messages
35
Location
California
I just replaced my speedometer cable and the speedometer started working again. So I took it for a test drive and all was well until suddenly it started making a growling noise and the needle jumped up to much higher speeds than I was going, and then would occasionally peg. If I put it in reverse and backed up a little, it would "reset", and be OK for a while, then do it again.

So I took the cluster out and drove the back of the speedo with a drill. Sure enough I could get it to "howl" and jump up to higher speeds. I laid the speedo on its face and drizzled a little Tri-Flow lube into the bushing that the cable goes into. Then I tried it with the drill again, and I was unable to replicate the howling problem.

My working theory is that what is supposed to be a magnetic coupling that slips a controlled amount somehow suddenly becomes a near-solid coupling, driving the needle way too hard. With the howl that goes along with that (on mine, at least), I'm thinking that maybe a bushing is shot and the magnet makes direct or semi-direct contact with the wheel for the needle. Or, there's dirt between them.

So far I have not been able to make it happen again since lubricating it.
 
Joined
Jul 5, 2020
Messages
35
Location
California
What are these terminals for at the top of the speedo housing (mine's a '73)? It seems to be a switch that closes when the speedometer indicates any amount of speed. One of the terminals is connected to the case ground, the other one goes to a white wire that goes out through the harness. Is this some sort of speed sensor?

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