Speedometer calibration?
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Posting Guru
Joined: Feb 2013
Posts: 1,323
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From: Sunny Florida
Speedometer calibration?
How do you recalibrate your dentsides speedo? The one in my wife's 77' is way off, going to get new tires right now, would like to get it to read accurately.
Cargo Master
Joined: Jul 2005
Posts: 2,313
Likes: 367
From: Kansas
assuming everything mechanical is functioning correctly, you will need to figure out how many teeth the driven gear on the speedo cable needs...
Ford Speedometer Gears for Automatic and Standard Transmission
there are several smartphone gps apps that will very accurately show your exact speed without timing a mile etc.
Ford Speedometer Gears for Automatic and Standard Transmission
there are several smartphone gps apps that will very accurately show your exact speed without timing a mile etc.
Cargo Master
Joined: Apr 2010
Posts: 2,600
Likes: 64
From: Billings, MT
I just went through this. Ordered a new gear from PATC for like $22 shipped. Speedo still reads about 3 mph fast but I believe that's how it would have been from the factory. Most factory speedos are calibrated to read slightly high so u can't blame the car company for your speeding ticket
Fleet Mechanic
Joined: Dec 2007
Posts: 1,512
Likes: 340
From: Wildwood Pa
Pull the current gear & count the teeth. If the speedo is currently reading fast, add teeth. Reading slow, subtract teeth.
If you figure the percentage of the speedo error, you can apply this same percentage to the tooth count to get close to what you need. Example: if your speedo is reading 10 percent fast, & gear is 18 teeth, you need a new gear with 10 percemt more teeth, or a 20 tooth gear. There are speedo gear sets for sale on ebay at very reasonable prices.
If you figure the percentage of the speedo error, you can apply this same percentage to the tooth count to get close to what you need. Example: if your speedo is reading 10 percent fast, & gear is 18 teeth, you need a new gear with 10 percemt more teeth, or a 20 tooth gear. There are speedo gear sets for sale on ebay at very reasonable prices.
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RangerHaywood
1973 - 1979 F-100 & Larger F-Series Trucks
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Aug 17, 2010 08:29 PM
