Speedometer Correction, Please Help!

[zainyD]

I must be pretty bad at math because I'm having a heck of a time trying to figure out what speedometer gear I need to buy in order to correct my speedometer. I have a 96 Ranger 4x4 with a m5od manual tranny. I have 5.13 gears and 35" tires. My current speedo gear has 19 teeth.

With the calculations that I've done I came up with both 23 teeth and 16 teeth. Are either of these accurate or are they not even close?!? Any help at this point would be greatly appreciated, thanks in advance.

 

[410Fortune]

4x4 correct?
What transfer case does that sucker use and the speed sensor is still in the tcase in a 96 ranger, right? We need to know how many teeth the drive gear inside your t case has, I will asssume its 7 teeth

23 tooth is the most they make, I believe its gonna be what you are stuck with...

Here's the math copied from Sections' thread:
I have 35s.

I threw the stock gear back in there because it would have been closer than the one I used for 32/33s. But it's still pretty far off.

Here's my calculations:

Speedometer Gear Teeth = (Drive Teeth * Rear End Ratio * Tire Revolutions per Mile) / 1,000

(7)(4.88)(576.52)
------------------
1000




19693.92
---------
1000



19.69 Tooth Gear = Pink


So for you
Speedometer Gear Teeth = (Drive Teeth * Rear End Ratio * Tire Revolutions per Mile) / 1,000


Tire revs = 35" x 3.146 = 110.1"
1 Mile = 5280' or 63360"
so 110"/63360" = 576 revolutions per mile.

T = (7*5.13*576) / 1000

20.6, so I would start with the 21 tooth

Now when I did this calculation it ended up being OFF
The one that worked for me was to use GPS to tell me my actual speed vs what the speedometer was displaying

 

[zainyD]

410, thanks for the help dude. Yes, my truck is a 4x4 and I have a BW1354 t-case with the speed sensor in the tail of the case. I was guessing a 8 tooth drive gear, but I wasn't sure.

How many teeth does the BW1354 drive gear have? I tried searching, but couldn't find what I was looking for. I'll see if I can't get some more info off Google.

 

[410Fortune]

should be 7
So far I have only seen 7 and 9 for Ford
yellow = 7
brown = 9

I THINK!!! hahaha
my 1354 has a yellow gear, so did my AWD case and I counted the teeth on the AWD yellow gear, def 7

Its not a bad idea at all to use one of those radar speed limit jobs to try and determine what your actual speed is compared to what the speedo says, if you dont have GPS. This seems to be the most accurate method.
I came up with 19.8 teeth needed, I installed a 20 tooth gear and its dead nuts on until about 72 mph then it starts to read just a bit slow, no biggie since I wont spend too much time about 75

 

[section525]

Oh, the ''how many teeth do I need' game. I suck at this. :

 

[zainyD]

*Update*

Ok, I just called the Ford dealership and found out that I do indeed have a 7 tooth drive gear. I also ordered a 21 tooth speedo gear so hopefully that'll get my speedo closer to where it should be.

I also got this helpful bit of information. Ford drive gears are also color coded

Purple = 6 tooth drive gear
Natural(Yellow) = 7 tooth drive gear
Green = 8 tooth drive gear

That should making the ID game a lot easier. Thanks for the help guys!

 

[410Fortune]

and brown is?
9 I am guessing

 

[zainyD]

Brown is probably 9, the person I spoke with just mentioned the three that I listed above.

 

[Glacier991]

<== still has all his teeth!