How to: Speedometer Gear Color Code Specification Chart With Formulas, And Ford Part Numbers.

[MrQ]

Brooklyn...

I pulled the speedo gear out of my auto and its a GREEN 16 tooth...not 17.

 

[1Byounkin]

My gear has 18 teeth. But my speed is 5 miles off. It shows 55 when I'm going 50.

235/75/R15 3.73LS 4WD
Is this right or is the gear off? Do I have to change both gears?

 

[jake122288]

ok...so i upgraded to 33's.... and using the formulas here i obtained the fact the i have a 19 tooth spedo gear (pulled it and looked) and with the tire change to 33's and using a set indicated speed as 55 by my calculations my actual speed is 62.80mph... then using the other formula using the 19 tooth x 55 (spedo reading) / 62.80 actual speed i come up with 16.64... i was just wondering if this sounded right and if i should go with the 16 tooth or 17 tooth spedo gear?

 

[nooberiffic]

So, originally my truck had 225/75/R15. They were changed years ago to 235/75R15. I was off a little on my speedo (was going faster than it indicated). So I changed my speedo gear (white 17 tooth manual trans) to the 16 tooth wine colored one.
Now I put 31's on my truck, and want to fix my speedo, but it doesnt show a smaller speedo gear than the 16 tooth one. Did I mess up and go the wrong way? BTW, I have 3.73 gears.

 

[Naasau]

My gear has 18 teeth. But my speed is 5 miles off. It shows 55 when I'm going 50.

235/75/R15 3.73LS 4WD
Is this right or is the gear off? Do I have to change both gears?

I have the same issue, I came up with a new gear tooth count of 16.59 for my 285/75r16's. What did you end up doing?

 

[Naasau]

Alright, it seems like if I go for the 16, my speedo will read faster than I'm actually traveling (I donno by how much); and if I go for the 17, it will read slower than I'm actually traveling... So my solution is going to be buy both of em, and compare them directly using GPS tracking.

As a side note, can anyone verify the statement that all 4WD X's use the manual tranny gears? B/c I'm rocking the A4LD and I really don't want to break anything.

 

[Naasau]

As a side note, can anyone verify the statement that all 4WD X's use the manual tranny gears? B/c I'm rocking the A4LD and I really don't want to break anything.

Verified!

Also, I picked up a 16 and a 17 tooth gear, then I put the 16er in first to try out.... and discovered that it is perfect! I guess the lesson is to always round down on these things.

 

[2TimingTom]

How much are these things anyway?

I need a 23 tooth gear. Will the dealership have these things in stock? Or should I order online somewhere?

And mine was a total PITA to get out.

 

[Naasau]

I got mine out nice and easy... I wonder why yours gave you grief. :shrug:

As for cost, they were each about five bucks, so... I'd say cheap. But I would also suggest that you call the dealership first, there was only one in the greater denver metro area that had the two I needed in stock.

 

[Currency]

@BrooklynBay, What happened to the pictures in the first post?

Having some issues with my speedo as well,
http://www.explorerforum.com/forums/showthread.php?t=357382

Going to pull my gear tonight and check it, mileage stopped going up, and of course I'm moving at 0MPH, but still using gas..... Bummer

 

[BrooklynBay]

External links with photos constantly change. That's why it's better to have images linked directly from this site.

 

[Xeek]

so i swapped from 26.4" tires with 3.08 gears to 28.03" tires with 3.73 gears.
my current gear is a green 17 tooth.

trying out 6/7/8 for drive gear in this i got a 7 tooth gear also. 6 and 8 came to 14 and 19, so thats not right. so i must have 7.
Driven Gear Teeth = (Drive Gear Teeth x Axle Ratio x Tire Rev. Per Mile) / 1000
16.98928 = (7 x 3.08 x 788) / 1000


now going here, http://www.grimmjeeper.com/gears.html

i plugged in the numbers for my tires, gears, tranny. and got my speedo readings.
speedo reading 77, actual speed 67. (3rd gear at 3000rpm)

so now: 19.5373134328 = (17 x 77) / 67.

rounding down gives me a tan 19 tooth for the new gear. correct?

 

[Naasau]

Sounds right to me, and rounding down is a better plan than rounding up (in my humble opinion).

 

[Xeek]

ford didnt have any. neither did any other ford according to them. looks like ebay it is. damnit

 

[Maniak]

ford didnt have any. neither did any other ford according to them. looks like ebay it is. damnit

Remember, its the same gear as a manual transmission driven gear. Ford has been using those since the 70's. Look at places that sell to mustang people.. You'll have a better chance of finding it.

I'm talking like latemodelrestoration and american muscle etc.

If they ask, its the short snout driven gear for use in the xfer case.

~Mark

 

[Xeek]

Yea I googled it. Found american muscle had it. $7.99 shipped. They have just about all of them on there..
I need the long nose one, 2wd with no transfer case for me lol.

 

[Maniak]

Yea I googled it. Found american muscle had it. $7.99 shipped. They have just about all of them on there..
I need the long nose one, 2wd with no transfer case for me lol.

Doeth, You need the one for the auto trans.. I need to remember there are people with 2 wheel drive explorers..

~Mark

 

[Xeek]

Ranger but you were close lol

 

[Naasau]

2 wheel drive.....? But.... but... why?

 

[Xeek]

Because saving weight? Lol. Street DD truck. Although something tells me ill need the purple 21 tooth in the future tho..