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Discussion Starter #1
I have a 1991 f-250 with the 7.3 idi. the motor was rebuilt right before I bought the truck. the speedo has never worked on the truck since I bought it. every now and then it will bounce up and down. the transmission shifts really rough. what do I need to do to make it stay in overdrive, shift smoothly, and fix the speedo?
 

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There is a cable for the speedo on a 91 that runs from the back of the trans, or transfer case. Maybe the gear is stripped. There is a cable and a couple wires. The wires I believe run to some kind of speed sensor. That has to work on a E4OD for the trans to shift right.
 

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I replaced the cable to the speedo. the only thing that changed was it started bouncing up and down every now and then when u are driving down the road. Do you think the gear is stripping out or something?
 

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The gear could be stripped it is just plastic. There i a speed sensor that you would have plugged the cable into when you changed it. It sticks out of the transfer case 2'' or 3'' and has a couple wires coming from it. It is held in with a small nut. Take the nut off and pull it out of the transfer case, you will see the gear. The gears that are wore might not look to bad a first glance, so look close. The gear on the cable is easy to change just held on with a clip. If you have to change the inside gear,you will have to pull the rear shaft and the tail housing on the transfer case. Then you will see a clip next to that gear, pull that clip then slide that gear off the shaft. There is a small steel ball that holds the gear from spinning, don't loose it. I am not sure how the gear is if you have a two wheel drive.


In that speed sensor there is a short piece of cable that runs through it. That could be broke or twisted.


If you could spin the gear fast enough, and have someone watch the speedo you my be able to narrow it down.
 

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Those gears are available from a Ford dealer, just make sure you get the correct color of gears, the speed sensor is available also, not to expensive.
 

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Discussion Starter #7
I have done everything I can think of. I changed the fluid filter. I have replaced the gear in the transmission for the speedo cable. I have changed the speedo cable. the speedometer is working now and it will go into overdrive, but after I fixed all that it quit driving. the only gear that works now is reverse. what is the best next step???
 

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I have the same year truck and I'm in the process of working out a speedo gremlin. The truck is not computerized luckily, so they're aren't many sensors that control the tranny. If your only getting reverse, that sounds like a internal trans problem. That happened on my '97 F350 PS and I had to rebuild it. Check the linkage?
 
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