Speedometer Correction
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Cargo Master
Joined: Aug 2015
Posts: 2,075
Likes: 101
From: Marana, Arizona
Speedometer Correction
I'm in the process of a Dana 60 swap into my 52 F3 as well as a tire size change.
Based on an online calculator going from the 4.86 stock gear ratio to a 3.73 @ 60 MPH on my speedo, my actual speed will be 78.18 MPH.
Going from the 7.50-17 tire to a 235/85R 16, 60 MPH on my speedo will be 56.43 MPH actual. (Roughly) had to type in a modern equivalent tire size of 33.7"
So I'm guessing my speedo will be reading about 14-15 MPH high.
Is there speedo drive gear options for the T-9 to correct the difference?
I had choices on an early Mustang. Not so familiar with the trucks.
Based on an online calculator going from the 4.86 stock gear ratio to a 3.73 @ 60 MPH on my speedo, my actual speed will be 78.18 MPH.
Going from the 7.50-17 tire to a 235/85R 16, 60 MPH on my speedo will be 56.43 MPH actual. (Roughly) had to type in a modern equivalent tire size of 33.7"
So I'm guessing my speedo will be reading about 14-15 MPH high.
Is there speedo drive gear options for the T-9 to correct the difference?
I had choices on an early Mustang. Not so familiar with the trucks.
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Joined: Sep 2006
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Cargo Master
Joined: Aug 2010
Posts: 2,927
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From: Houston
I did a quick Google search for those part numbers. The drive gear is widely available, even on that auction site. Dennis Carpenter is supposed to have two of the driven gears.
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Cargo Master
Joined: Aug 2015
Posts: 2,075
Likes: 101
From: Marana, Arizona
wavetrain, that link got saved to favorites. THANKS!
38coupe, Thank you too! I'm going to compare the tires side by side. Most of what I have found regarding the stock 7.50-17 tire says it is 34" tall. The 235/85R16 is listed as 31.7" tall with slight differences by brand.
Once I chuck those widow makers and get the new tires and rims on I guess I could use my phone GPS and see how far I'm actually off.
I read a bunch of threads for the Dana 60 swap but, have not seen the information about what adaptor U-joint is used or mention of the speedo error. UNTIL NOW!
THANK YOU!
Now I just have to figure out rear shocks. Mine didn't come with any. Once I get my swap done I will post pics and list all parts.
38coupe, Thank you too! I'm going to compare the tires side by side. Most of what I have found regarding the stock 7.50-17 tire says it is 34" tall. The 235/85R16 is listed as 31.7" tall with slight differences by brand.
Once I chuck those widow makers and get the new tires and rims on I guess I could use my phone GPS and see how far I'm actually off.
I read a bunch of threads for the Dana 60 swap but, have not seen the information about what adaptor U-joint is used or mention of the speedo error. UNTIL NOW!
THANK YOU!
Now I just have to figure out rear shocks. Mine didn't come with any. Once I get my swap done I will post pics and list all parts.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
Check out page 748 of your 48-56 Ford Truck Parts Catalog (page 773 in the PDF version). I'm pretty sure the 7 x 17.5 tire is about the same height as your 235/85R16.
So the gear set you want is drive gear 8J 17285 and driven gear 01T 17271-A
I did a quick Google search for those part numbers. The drive gear is widely available, even on that auction site. Dennis Carpenter is supposed to have two of the driven gears.
So the gear set you want is drive gear 8J 17285 and driven gear 01T 17271-A
I did a quick Google search for those part numbers. The drive gear is widely available, even on that auction site. Dennis Carpenter is supposed to have two of the driven gears.
HAVEN FORD in Haven KS has 1 = 620-465-2252.
CARPENTER NOS OBSOLETE PARTS in Concord NC has 2 = 800-476-9653.
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8J-17285 .. Drive Gear / Obsolete
WESLEY OBSOLETE PARTS in Liberty KY has 2 = 606-787-5293.
PARTS INTERNATIONAL in Farmers Branch TX has 7 = 888-727-0418.
GREEN SALES CO. in Cincinnati OH has 9 = 800-543-4959.
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Cargo Master
Joined: Aug 2015
Posts: 2,075
Likes: 101
From: Marana, Arizona
The amount of knowledge on this site just blows me away. AND.....everybody just jumps right in and helps. I really do search for hours at times to TRY to find what I need. I usually find some of what I need in dead end threads. I do my best to give back by posting complete threads. Pics and all needed parts. I hate dead end unresolved threads.
Cargo Master
Joined: Aug 2010
Posts: 2,927
Likes: 135
From: Houston
True, 7.50-17 tires are approximately 34" tall. However, the chart I am referring to isn't referencing 7.50-17 tires. The chart is referencing tires for 17.5" wheels.
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