Speedometer Gear help..

[Salugo]

I have a 1994 Ford Ranger, 4 cylinder, 5 speed, with 4.10s, sitting on 31s.

My speed is off, it also wiggles until it gets to around 45 mph on the gauge.

I was wondering if anyone could help me figure out how many teeth i would need?

I used to have, 3.55s, with 26" tires. If that helps.

Thanks in advanced!!

-Tony

 

[Captain Ledd]

I'm going to guess 2wd?

1. You need to find out how many teeth are on your transmission output shaft gear.

Then plug stuff into this equasion:

Drive gear teeth (the gear on the output shaft) X Axle Ratio X Tire revolutions per mile

Divide that number by 1001

This will be the driven (the one that's REAL easy to change) gear tooth number.


EDIT:

Tire revolutions per mile:

20168 (divided by) "Tire diameter in inches".

http://www.transmissioncenter.net/speedometer_calibration_______va.htm
The Ford stuff is roughly half way down.

I used to have a thing that color coded the gears to tooth counts but I can't find it.

Clean off a tooth you can see through the hole in the transmission so you can put a black permanent marker stripe on it. You might need to pull the driveshaft for a moment but rotate the shaft and count the number of teeth until you see that black mark again. Then do the above equasion.

Round to the closes whole number, if it's near the middle, round down.

 

[Salugo]

Wow! Thanks so much!

Looks like i have something to do tomorrow ha.

 

[Insanejughead]

Wow! Thanks so much!

Looks like i have something to do tomorrow ha.

Not going to lie, it's pretty awesome that you showed enthusiasm and excitement to learn this stuff, rather than asking someone to just give you an answer.

 

[kryptonitecb]

I think the tech library has a write up on this also.

Sent from the road while ignoring traffic

 

[adsm08]

I used to have a thing that color coded the gears to tooth counts but I can't find it.

Here it it:
http://www.therangerstation.com/tech_library/Speedogear.html

I think the tech library has a write up on this also.

The tech library and google both have a ton of stuff on figuring out the gear you need to fix the speedo.

A lot of it is really confusing or hard to do if you don't have all the numbers on hand.


Ledd's equation is one of the better methods I've seen.

This calculator is also pretty good.
http://jimroal.com/drive.htm

 

[Captain Ledd]

Ledd's equation is one of the better methods I've seen.

This calculator is also pretty good.
http://jimroal.com/drive.htm

I love using this equation. Not only is it almost fool-proof, it only uses existing parts that are right in front of you that you are using. Unlike a lot of other equations like what was the original reading on the speedo vs now, or previous ratios or teeth that may not be around anymore or have long since been forgotten.

 

[adsm08]

I love using this equation. Not only is it almost fool-proof, it only uses existing parts that are right in front of you that you are using. Unlike a lot of other equations like what was the original reading on the speedo vs now, or previous ratios or teeth that may not be around anymore or have long since been forgotten.

The only part I don't like about yours is that all the teeth on the internal gear can't always be seen without some trans disassembly, and some transmissions, like the ZF5 have different drive gears with different tooth counts.

 

[Salugo]

Not going to lie, it's pretty awesome that you showed enthusiasm and excitement to learn this stuff, rather than asking someone to just give you an answer.

Well everyone definitely pointed me in the right direction.
It was still interesting for me to figure out but i got.
The parts are on their way.

Thanks everyone for all your help!

-Tony

 

[Captain Ledd]

The only part I don't like about yours is that all the teeth on the internal gear can't always be seen without some trans disassembly, and some transmissions, like the ZF5 have different drive gears with different tooth counts.

Like I say, I used to have a thing with all the drive gears with their colors and tooth counts listed, but I have since lost that information. I know it's a choice of 6,7,or 8 teeth.

I'm pretty sure 6 was purple and 7 was red or natural? can't remember the 8 tooth count at all.

and then it's different for the transfercases, a red gear was 6 teeth. not sure about 7 or 8 tooth counts.

 

[adsm08]

I just pulled a red 7-tooth out of a BW1350 on Saturday.

I think the ZF5 7-tooth was white and the 8 was black.

The one on my 1354 looks pink, so it was probably white when it was new, what with the red fluid and all.