Speedo problems

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Apr 23, 2017 | 02:39 PM

LIQUID8

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Joined: Apr 2015

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Speedo problems

I have been having issues with my speedometer bouncing while driving. First of all my speedo is registering about 15 mph slower than it should be. On top of that it bounces around. I also recently noticed my odometer is substantially off. I replaced the speedometer cable hoping it would help but I see no change. Is this likely because of old faulty gauges or is there something else that could be causing my issues? Thanks for any help.

Apr 23, 2017 | 03:04 PM

Ford_Six

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Joined: Oct 2002

Posts: 18,488

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From: The Big, Oregon

Taller gearing will change the reading. You can get a new gear from Ford or a speedometer company. I have used Tacoma Speedometer a few times with good results.
Here's a calculator for which gear you need
Speedometer Gear Calculator and Charts - TCI® Auto
One of the Ford parts guys should be able to translate tooth count into the color scheme that Ford used.

Apr 24, 2017 | 05:58 PM

JEFFFAFA

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Joined: Mar 2013

Posts: 14,255

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From: Phoenix, Az.

Quote:

Originally Posted by LIQUID8

2X Jared. I think the problem is one or both of the speedo gears. Either the "drive" gear in the tranny or the "driven" gear end of the speedo cable. Remove the cable from the tranny. Reach in that hole to feel across the top of the speedo drive gear's teeth. The teeth should feel flat across. If the center of those teeth are worn out they will feel "dished". Dished equals bad gear. I would need color of the gear or number of teeth, 4X2 or 4X4, and which tranny you have to look up the drive gear.
On the "driven" gear, while you have that cable out of the tranny look at the color or count the number of teeth that gear is for me. And 4X4, A/T, or M/T? Each tooth equals 3-5 MPH. So it sounds like you need a driven gear with 4 less teeth than you have now.