stock speedo gear
Thread Starter
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Junior User
Joined: May 2007
Posts: 75
Likes: 0
From: SO CAL
stock speedo gear
hey guys. i got a 79 f150 custom. 4x4. 460/c6 np205 tcase...
i have been changing around tire sizes lately. I now have some 37inch michelin XMLs military tires. they will be staying for a while. but I havent changed the speedo gears yet...I took the one out thats on the cable..its a white gear with 17 teeth. Iam trying to get around tearing the tcase apart to get to the internal gear...does any know what it has? this truck has 4.11s in it..i bought the truck used..so i dont know if he changed the gear or not.
but if the white gear with 17 is stock..then iam sure the internal gear is stock..so what came with that 17 tooth gear? get what iam sayin?
i have a gps that i have hooked up...on the freeway the gps says iam doin 80mph...the speedo in the truck says iam doin 55MPH...so its way off...
any one know what to do? or what size gear i should try? and maybe where to get one?
thanks a lot guys. any help is appreciated
i have been changing around tire sizes lately. I now have some 37inch michelin XMLs military tires. they will be staying for a while. but I havent changed the speedo gears yet...I took the one out thats on the cable..its a white gear with 17 teeth. Iam trying to get around tearing the tcase apart to get to the internal gear...does any know what it has? this truck has 4.11s in it..i bought the truck used..so i dont know if he changed the gear or not.
but if the white gear with 17 is stock..then iam sure the internal gear is stock..so what came with that 17 tooth gear? get what iam sayin?
i have a gps that i have hooked up...on the freeway the gps says iam doin 80mph...the speedo in the truck says iam doin 55MPH...so its way off...
any one know what to do? or what size gear i should try? and maybe where to get one?
thanks a lot guys. any help is appreciated
Thread Starter
|
Junior User
Joined: May 2007
Posts: 75
Likes: 0
From: SO CAL
hey thanks for the reply. You were great help, dont be hard on your self!
I think i will just get some different sizes and try them out. see what gets closest. yea iam pretty sure that gps is right on..its dead on in my dads acura tl, and my moms lexus.. so iam sure its right.
hey where did you get your gear? any online places or stores?
thanks
I think i will just get some different sizes and try them out. see what gets closest. yea iam pretty sure that gps is right on..its dead on in my dads acura tl, and my moms lexus.. so iam sure its right.
hey where did you get your gear? any online places or stores?
thanks
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
There are 7 different tooth count speedometer driven gears (at the end of the speedo cable).
Tooth count: 16 / 17 / 18 / 19 / 20 / 21
There is no such thing as a stock speedo gear since the gears tooth count is based on what the rear axle ratio is and the type of transmission.
The tire size also fits into the equation.
All the gears are still available from Ford.
There are two types of gears: Some have teeth that go this-away: //// This is the most common type used after 1972.
Some have teeth that go that-away: \\\\
If you have "fat" tires, you may also have to change the drive gear on the output shaft to get the speedo to read correctly.
There are at least 4 different drive gears used in the 1970's.
----------------------------------------------------------
OP: What's the (original) rear axle ratio?
Rear axle ratio: Look on the Warranty Plate, on the left door face below the latch for the AXLE code...post what the code is, I'll decode it for you.
btw: The engine size makes no difference on speedo gears.
Tooth count: 16 / 17 / 18 / 19 / 20 / 21
There is no such thing as a stock speedo gear since the gears tooth count is based on what the rear axle ratio is and the type of transmission.
The tire size also fits into the equation.
All the gears are still available from Ford.
There are two types of gears: Some have teeth that go this-away: //// This is the most common type used after 1972.
Some have teeth that go that-away: \\\\
If you have "fat" tires, you may also have to change the drive gear on the output shaft to get the speedo to read correctly.
There are at least 4 different drive gears used in the 1970's.
----------------------------------------------------------
OP: What's the (original) rear axle ratio?
Rear axle ratio: Look on the Warranty Plate, on the left door face below the latch for the AXLE code...post what the code is, I'll decode it for you.
btw: The engine size makes no difference on speedo gears.
