CJ7 Speedometer issue - works with drill - JeepForum.com
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post #1 of 3 Old 09-25-2017, 12:40 PM Thread Starter
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1978 CJ7 
Join Date: Mar 2014
Location: Birmingham
Posts: 11
CJ7 Speedometer issue - works with drill

On my 1978 CJ7, the speedometer hasn't worked since I bought it years ago. I unscrewed the cable from the transfer case today and put a drill on the cable and the speedometer works fine. It looks to me like the piece that the cable screws into on the transfer case may be bad. It seems to be about a 1" nut that would unscrew this piece from the transfer case, but there is not enough clearance around that nut to fit a socket. Just looking into the end of the place where the cable goes, it seems to be too large of an opening to grab the square cable. Is there a special tool for removing these? After verifying that the cable is working, the problem has to be right there at the transfer case but I have no experience dealing with this sort of thing. Any suggestions for troubleshooting this issue? Thanks in advance for your help.

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post #2 of 3 Old 09-25-2017, 12:54 PM
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1986 CJ7 
Join Date: Jun 2001
Location: Mobile
Posts: 5,461
Sounds like the square drive in the speedo gear is mess up. Put the tea case in neutral and spin the yoke by hand while you look in to confirm that the Square Drive is indeed turning with the yoke rotation. If it is, you may be able to rig something by inserting a thin piece of wire inside the square hole to take up the worn space.

Yeah, the one time I removed one of the dana 20 speedo gears, I happen to have a socket with thin enough walls and it worked but was tricky.

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post #3 of 3 Old 09-26-2017, 06:38 AM
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1978 CJ5 
Join Date: Aug 2011
Location: Munster
Posts: 578
Yeah, I had to grind down the outside of a socket to get mine out. I would put it on the transfer case and disconnect it from the speedo but leave it hanging in the cab so that you can see if it is spinning when you drive. The most recent speedo cable I bought was just a little bit too long and caused the speedo mechanism to bind and not function at all. I did the same thing where I could spin it with a drill and the speedo worked and then I did what I described above to confirm that the T case was spinning the speedo cable. At that point I was concerned that the plastic drive gear on the shaft in the t case was loose (apparently they are just friction fit to the shaft) and I was going to have to take apart the tcase and epoxy it on the shaft (as someone on here had said they had done) but I trimmed a bit off the end of the speedo cable that went in the speedo and that solved the problem.

Good luck!
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