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

[mechroneal]

...Those markers are pretty much useless so I wouldn't worry about it..

...You could borrow somebody's GPS for a day or 2 and get a better idea of your speed vs. speedometer ...Since I got my GPS I know my X is right on the money while my Ranger is dead on till 50 mph...Then I am doing 55...

...If you can do 65 and be within 1-2 mph, no sweat...

I'm using an official designated 'Speedometer Check Zone' and it is consistently off. I am dubious about the accuracy of GPS, given its 'accurate to 10-20 feet' caveat.

 

[Tbars4]

...Check your local listings for a speedometer shop or check with your local truck stop...They will know where one is...That is, as long as you have bone stock tires on your vehicle...If not, the first post of this thread or, the "How to" in my signature may have some more information and conversion charts you may need..

...As for testing with my GPS, I usually drive more than a mile and I did several 100-200 mile trips to verify my speed and it was easy to do as long as you can keep a steady pedal...:scratch: ...I never thought about a 10-20' caveat being a problem in a gps calculation over 5,280 feet...I figure that is close enough as all manufacturer's of vehicles have a variance depending on their electronics or mechanics that measure speed, including radar vs. lazer...

...I have found this a nifty little conversion chart when I want to get my pencil out and study actual speed, degrees, etc...
http://www.onlineconversion.com/

 

[rkneeshaw]

Did anyone ever find an answer to this:

Ok, so if I pull the VSS back out, the gear I'm looking for is what my 19 tooth gear fits into? Is it labeled or do I just count the threads? How do I determine if it has 6, 7, or 8 teeth? Thanks again, Brooklyn.

I too am needing to know if the drive gear in the 1354 transfer case has 6, 7, or 8 teeth so that I can complete my calculations...

 

[BrooklynBay]

Take a marker, and make one tooth a different color, then rotate the gear to count the teeth.

 

[rkneeshaw]

Take a marker, and make one tooth a different color, then rotate the gear to count the teeth.

This can be done with the transfer case still on the vehicle, and without moving the vehicle? (Note I'm talking about the gear inside the transfer case, not the speedometer gear on the end of the VSS...)

 

[BrooklynBay]

You have 2 options. The first one is to put it on a lift so that the rear wheels could turn while this inner gear turns. The second is to remove the rear driveshaft.

 

[SuRrEaLNJ]

I count 7 teeth on this gear

 

[SuRrEaLNJ]

alright so then for me using the ford racing method it would be

7 teeth on drive (assumed)
4.88 ration
35x12.5x15 = 598 revs/mile

(Drive Gear Teeth x Axle Ratio x Tire Rev. Per Mile) / 1000.

(7 x 4.88 x 598)/1000
(20427.68)/1000
20.42768

wich would be closest to a 20 tooth gear? i kinda split the diff between the 20 and 21 nicely i guess.

 

[K80]

Here's a link to a speedometer gear chart with part numbers: http://www.tciauto.com/components/speedometer_gears.htm. This link is from the same website with a speedometer gear computation program in addition to a chart: http://www.tciauto.com/tech_info/speedo_gears.htm.

These links are 404....

Here are the updated ones...

http://www.tciauto.com/Products/components/speedometer_gears.asp

http://www.tciauto.com/Products/TechInfo/speedo_gears.asp

 

[clwhitt]

You have 2 options. The first one is to put it on a lift so that the rear wheels could turn while this inner gear turns. The second is to remove the rear driveshaft.

Can the drive gear be removed without splitting the transfer case?

 

[SuRrEaLNJ]

yes

 

[clwhitt]

yes

Not the driven gear, but the drive gear behind the yoke? Does that one nut allow the yoke to be pulled off?

Thanks for the picture.

Chuck

 

[SuRrEaLNJ]

goes to show my reading comprehension. on that one i have no idea

 

[explorerguy89]

wow i didnt think it was that easy =p

 

[clwhitt]

goes to show my reading comprehension. on that one i have no idea

I dropped the driveline (12mm -12 point) and took the yoke off (30mm socket). Pulled the seal off and with a dental pick, was able to pull the speedometer drive gear out (after previously removing the vehicle speed sensor and the driven gear). Other than the torques involved, not too difficult.

Chuck

 

[lugnuts55]

'96 Explorer 4.0 OHV 4WD


I've been getting a code P1500 VSS Intermittent for a while and changed the sensor after checking the wiring. The harness was routed clear of obstructions and not chafed that I could see. I keep getting the code.

I was under the vehicle a couple weeks ago for something else and decided to look at the VSS again. I pulled it out and stuck my finger into the hole to see if I could feel the drive gear. It's there and it moves! I was told that the drive gear is held in place by the flange and flange nut. I was not able to tighten the nut because I don't have a compressor and impact tools. Also, my speedo reads 5mph fast. Is this possibly the reason for the error and the code?

 

[clwhitt]

I'd like to post a diagram of the 1995 transfer case I acquired, but I'm having a bit of a problem figuring out how post the picture. The link to my picasa web page did not work.

 

[lugnuts55]

clwhitt, this is the link that was sent to my mail box. Thanks for sending this exploded view. I think it confirms what I was told about the speedo drive gear being held in place by the flange nut.
There is no nomenclature but looking at the output shaft, it looks like there is no clip holding the speedo gear in place.
My question then is, what is the torque for the flange nut or is it tighten it until the drive gear no longer spins.
I hope I didn't hijack this thread but this seemed to be related and appropriate. Thanks again for the help.


http://picasaweb.google.com/clwhitt/Explorer#5446444251114754386

 

[clwhitt]

My question then is, what is the torque for the flange nut or is it tighten it until the drive gear no longer spins.
I hope I didn't hijack this thread but this seemed to be related and appropriate. Thanks again for the help.

http://picasaweb.google.com/clwhitt/Explorer#5446444251114754386

Yes, that's the drawing (what's the secret to inserting it here?). I don't know what the torque is, but it was damn tight. So tight that I actually twisted the head off my 1/2" torque wrench while trying to take one apart in a wrecking yard (my university, why experiment on my car). So I just tightened it damn tight putting it back together on my car. And all works well, in fact, the speedo is so much smoother than anytime previous.

 

[Explorer Junky]

speedo

When I had stock sized tires and gears, my speedo always read 4 mph high. When I bought my BFG's A/T's at 31", it was right on the money! My dad also has same year (97) as mee, and his reads 4 high also with stock sized tires.