I need some advice!!
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Joined: Jan 2004
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From: Topeka, Ks.
I need some advice!!
I would like to get my speedo corrected in my 86 F150. I know it is way off and have FINALLY got the silly thing to run right. Now I am down to getting the speedo correct.
Here is what I have:
86 F150 with a 302.
Trans. type K
Axle type 18
Tires are P235/75/R15
I know on this type of tranny it is just a matter of changing the speedo gear but which one do I need?
Mark
Here is what I have:
86 F150 with a 302.
Trans. type K
Axle type 18
Tires are P235/75/R15
I know on this type of tranny it is just a matter of changing the speedo gear but which one do I need?
Mark
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Joined: Aug 2003
Posts: 3,705
Likes: 4
From: Wichita KS
Hey Mark,
Here is a link to TCI transmision's gear calculator, enter the numbers and it will tell you what gear you need.
http://www.tciauto.com/tech_info/speedo_gears.htm
Duane
Southeast Kansas Coordinator
Here is a link to TCI transmision's gear calculator, enter the numbers and it will tell you what gear you need.
http://www.tciauto.com/tech_info/speedo_gears.htm
Duane
Southeast Kansas Coordinator
Post Fiend
Joined: Jan 2004
Posts: 6,610
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From: Northwest, Arkansas
According to the chart it should be a 3.00 check the following thread.
https://www.ford-trucks.com/forums/s...ht=axle+codes+
https://www.ford-trucks.com/forums/s...ht=axle+codes+
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Mark,
If you've changed Tires size this link will help you figure that:
http://www.miata.net/garage/tirecalc.html
If you've changed Tires size this link will help you figure that:
http://www.miata.net/garage/tirecalc.html
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From: Topeka, Ks.
According to Jons link, I am 9% off on my speedo. 60 mph = 65.3 actual.
Thanks Jon!!
Duane, without putting too much thought into this, will a driven speedo gear that is 9% smaller give me the correct readings?
Mark
Thanks Jon!!
Duane, without putting too much thought into this, will a driven speedo gear that is 9% smaller give me the correct readings?
Mark
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Joined: Aug 2003
Posts: 3,705
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From: Wichita KS
I thought code 18 was a 3.08 gear 3800# capacity open diff??
Mark, You should pull the drive gear out of the tranny and see what color it is. Then look at the door sticker and see what tire size originally came on the truck. Then call ford and tell them what the truck originally had for axles and tires then tell them what you have now. If they ask your tires revolution constant is around 9.72.
Just going with a drive gear that is 9% smaller won't work since the ratio for the gear is a combonation of both gears so using a 9% smaller gear will get you about 12% speedo difference.
Duane
Southeast Kansas Coordinator
Mark, You should pull the drive gear out of the tranny and see what color it is. Then look at the door sticker and see what tire size originally came on the truck. Then call ford and tell them what the truck originally had for axles and tires then tell them what you have now. If they ask your tires revolution constant is around 9.72.
Just going with a drive gear that is 9% smaller won't work since the ratio for the gear is a combonation of both gears so using a 9% smaller gear will get you about 12% speedo difference.
Duane
Southeast Kansas Coordinator
Postmaster
Joined: Aug 2003
Posts: 3,705
Likes: 4
From: Wichita KS
I just did all the math and pulled the drive gear out of my 85 just to check, then called ford and you need a 17 tooth gear to correct the speedo, and they run about 8 bucks.
Duane
Southeast Kansas Coordinator
Duane
Southeast Kansas Coordinator
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