Brain Teaser

[John]

A few days ago the speedo on my SG quit working, 8 miles after resetting it. Ok, I figured, the cable broke, I've got a spare. I disconnected the cable at the speedo, and started to pull it out of the sheath, expecting to pull out an abbreaviated cable, but to my amazment, it was intact. Hmmm...Next, I removed the sheath from the drive, and reinserted the cable and reattached it to the speedo. Next I chucked the drive end of the cable up to a drill motor, and pulled the trigger. Nothing. Great, I need a speedo. That bummed me out because I have over 97 k miles showing, and I wanted to see it hit 100k. Well, it was a reversable drill, so I reversed it and Viola (walaa) it worked! I spun it up to 45 mph. I reassembled it and test drove it...nothing. Ok, it must be the drive. I jacked up the front and pulled the front wheel just enough to remove the drive, but I didn't pull the rotors from between the brake pads. I used a small screwdriver to turn the drive, and it worked properly. I disasembled the drive. cleaned out the old grease, and relubed it with Lubriplate. I reassembled the drive and reinstalled it, making sure the tabs of the driver in the hub aligned with the slots in the speedo drive. I road tested it again, nothing. I have three spare drives and I tried each one, and each time the same result, nothing. After about an hour of fn' with it, I finally figured it out. Anybody want to take a quess as to what I finally discovered?

[skids]

Re: Brain Teaser

The cable was not connected inside the speedo? Because the sheath ends were apart, shortening the effective length of the inside???

Originally posted by John
Anybody want to take a quess as to what I finally discovered?

[randy]

The drive cam inside the wheel hub was sheared.

[skids]

OK, maybe you tried to spin the speedo with a DRILL BIT and rounded the hole? (running and ducking) :-)

[John]

Wow Randy, you're close. Apparently, last time I had pulled the wheel, I didn't get the tabs lined up with the slots in the drive and the pressure of the drive against the tabs was enough to make the drive work, but finally, the tabs on the cam had fatigued enough to allow the them to bend away from the drive and not engage. I had a spare wheel, so I pulled the cam from it, and swapped them out. It worked. I had orginally thought that the tabs had sheared, but I noticed the bending only after completing the swap. I was able to straighten them out, and the cam can be used again.
Yeah Skids, I have a SQUARE drill bit, but you you got me on that one.

[Jerry]

Similar thing happend t my XJ...speedo needle was dancing, then quit entirely. Speedo drive plate (in front hub) was broken, tabs sheared clean off. I replaced and lubed the plate, seal, other parts plus I pulled the drive gear and re-lubed the shaft the main gear rides on. Speedo works fine and needle is steady. Is also a good time to check your wheel bearings.

[randy]

So, John,

Do I win half a prize!?

[John]

Randy, you win my respect and admiration, but you've had that for some time. I know it's not much, but it's all I can afford.