1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks Discuss the Early Eighties Bullnose Ford Truck

Speedo wont work

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Old 03-09-2012, 08:11 AM
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Speedo wont work

I am working on a 83 f150 with a 302. Just swapped in a new transfer case. I use to have NP205 and Swapped in a BW 1345. But now my Speedo does not work. It was working when I pulled the 205. Does any one have any ideas?
 
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Old 03-09-2012, 08:23 AM
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Is it not moving at all? You will want to make sure that the drive gear and driven gear are both meshing. Are you sure the drive gear is the same as what was on the 205? You may have to switch the driven gear on the speedo cable.
 
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Old 03-09-2012, 08:38 AM
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The speedo does not move at all. I am not sure if they mesh up. But I had an extra 1345 for parts and pulled the gear on the cable and swapped it, and it still does not work.
 
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Old 03-09-2012, 08:45 AM
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Have you checked the speedo cable to make sure it is turning at both ends?
 
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Old 03-09-2012, 08:49 AM
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I have not. How do I check to see if the cable is working?
 
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Old 03-09-2012, 08:54 AM
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Originally Posted by albinorhino
I have not. How do I check to see if the cable is working?
I don't know about how yours is run, but I just recently replaced my whole cable and it took me all of about 15 minutes to do the whole job. I would say if you had help, you could just unhook both ends and hook up a drill at the speedometer side and turn it slowly, the person underneath could tell you if it was turning. If it is only you, I would just remove the cable completely then check it the same way. Someone else may chime in with a better or easier way to check it.
 
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Old 03-09-2012, 09:00 AM
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If I have to replace the entire cable. What is the easiest way to do it. Do I need to pull dash apart?
 
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Old 03-09-2012, 09:07 AM
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Originally Posted by albinorhino
If I have to replace the entire cable. What is the easiest way to do it. Do I need to pull dash apart?
Not the whole dash, but enough to get the gauge cluster out far enough to disconnect the speedo cable. Once you dis-connect both ends, you should be able to fish it out.
 
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Old 03-09-2012, 10:30 AM
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I would just disconnect it from the transfer case and twirl the end of the cable (maybe with a drill if so inclined) and see what the speedometer does.

I forget which way it's supposed to turn, I think clockwise....
 
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Old 03-09-2012, 09:34 PM
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Ok. So I spun the gear on the cable, and its not the speedo cable. I talked to the transmission warehouse here in town and they have the gear inside the transfercase but said that it takes advanced calculus to figure out which gear matches up with the it on the speedo cable. Anyone have any help for me please. I flunked calculus.
 
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Old 03-09-2012, 09:39 PM
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It's easier than you think. If you can find out how many teeth the drive gear has, what you're rear diff ratio is, and how tall your tires are there are calculators that will tell you how many teeth you need on the driven gear.

Here is a simple one:

Speedometer Gear Calculator

Usually you'll put in 1000 for revs/mile.
 
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