For The Speedometer Guru's...
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Posting Guru
Joined: Oct 2007
Posts: 1,144
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From: Sedro-Woolley, WA
For The Speedometer Guru's...
For my 65 F100-
390/C6
26 1/2" od tires(235/60-R16)
3.53 gears
I currently have a red speedo drive gear in it but haven't had a chance to try it out. Am I close to the right gearing? Which one would be correct?
390/C6
26 1/2" od tires(235/60-R16)
3.53 gears
I currently have a red speedo drive gear in it but haven't had a chance to try it out. Am I close to the right gearing? Which one would be correct?
Elder User
Joined: Apr 2008
Posts: 619
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From: Montpelier, VA
I wish we could make this computation a sticky as this issue comes up fairly often. Here you go:
Speedometer Calibration Program - Method 1
Speedometer Calibration Program - Method 1
Elder User
Joined: Apr 2008
Posts: 619
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From: Montpelier, VA
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
How many teeth does the red DRIVE gear have? DRIVE gear on output shaft, DRIVEN gear at end of cable.
Back then, parts catalog listings of nylon speedo gears did not go by colors, only by the tooth count and if the teeth ran this-away: //// or that-away: \\\\
To figure out correct gears, the trans type, rear axle ratio and tire size must be known. 1964/72 truck parts catalog doesn't list radial tire sizes, so one needs a conversion chart.
Back then, parts catalog listings of nylon speedo gears did not go by colors, only by the tooth count and if the teeth ran this-away: //// or that-away: \\\\
To figure out correct gears, the trans type, rear axle ratio and tire size must be known. 1964/72 truck parts catalog doesn't list radial tire sizes, so one needs a conversion chart.
Cargo Master
Joined: Feb 2004
Posts: 2,081
Likes: 175
From: Central Texas
Hate to hijack here, but I'd like to get mine closer too. My issue is the trans driven gear is a machined steel piece the likes I have not seen anywhere. IIRC the trans (C6) was out of a '70. I'm running a 3.73 gear, 245/75/16 tires.
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Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
01T-17271 Steel DRIVEN speedo gear for your application could be either TYPE 7 or TYPE 8. These gears were introduced in 1940, were still being used for some applications in the 1970's.
Look on the gear for its stamped number, post what it is.
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I can figure about half of what is necessary on that page (my ratio is 3.54 and I can measure my tire height) but what numbers should I use for the drive gear teeth and speedo revs/mile?
I am running a 66 F250, 4 spd manual, and custom cab speedo.
Elder User
Joined: Apr 2008
Posts: 619
Likes: 1
From: Montpelier, VA
Thanks for the relink!
I can figure about half of what is necessary on that page (my ratio is 3.54 and I can measure my tire height) but what numbers should I use for the drive gear teeth and speedo revs/mile?
I am running a 66 F250, 4 spd manual, and custom cab speedo.
I can figure about half of what is necessary on that page (my ratio is 3.54 and I can measure my tire height) but what numbers should I use for the drive gear teeth and speedo revs/mile?
I am running a 66 F250, 4 spd manual, and custom cab speedo.
Cargo Master
Joined: Feb 2004
Posts: 2,081
Likes: 175
From: Central Texas
Are you sure about that? For some reason I thought it was 650, but I could easily be wrong(just ask my wife). I have no reason to not believe you, but that IS the magic number to hit.
Cargo Master
Joined: Feb 2004
Posts: 2,081
Likes: 175
From: Central Texas
3.73 ratio would be a Dana 60 from an F250 or a Dana 70 from an F350.
01T-17271 Steel DRIVEN speedo gear for your application could be either TYPE 7 or TYPE 8. These gears were introduced in 1940, were still being used for some applications in the 1970's.
Look on the gear for its stamped number, post what it is.
01T-17271 Steel DRIVEN speedo gear for your application could be either TYPE 7 or TYPE 8. These gears were introduced in 1940, were still being used for some applications in the 1970's.
Look on the gear for its stamped number, post what it is.
With that said, if I need another driven gear, where am I going to find it?
Thank you very much for this info.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
HAVEN FORD in Haven KS has 1 = 620-465-2252.
NOS PARTS LTD in Waxahachie TX has 2 = 972-937-2201.
CARPENTER NOS OBSOLETE PARTS in Concord NC has 3 = 800-476-9653.