Engine/Transmission (1994 - 1998) Speedometer gear?

[RLC77]

I am in the process of changing my gears from 3. 55 to the 4. 10's. I have a 97 turbodiesel, auto, 4x4 w/ 33" Bfg mud terrains. After changing from the stock tires to the 33's when i bought the truck, i changed the stock speedo gear (31 tooth/green) to a 30 tooth/yellow gear and that just about put me right on. I don't know where to start with the 4. 10's. I don't want to go out and buy a bunch of speedo gears. Is anybody out there running an auto 4x4 w/ 33" tires and 4. 10's and has corrected the speedometer by changing to the correct tooth speedo gear? What tooth gear are you using?

Also there is a sensor on top of the rear diff. Does that have to be changed when changing to different gears?

I also want to change the ball sockets on the throttle rod. It looks like they are just pressed onto the ball. Is there a trick to getting them off without bending the rod?

Thanks for the help boys and i will let you know how the gear swap went in a couple of days. The truck has been real doggy off the line with the taller tires and the 3. 55's. My computed final drive(from issue 32, page 16) with the 33's and 3. 55's is about 3. 30 . The new final drive with the 4. 10's should be about 3. 80 . That's what i'm looking for. I was stupid for not ordering the 4. 10's when i bought the truck. Live and learn the hard way.

 

[fest3er]

According to my math:

30 tooth X tooth
--------- = --------
3. 54 4. 10

X = 30 * 4. 10 / 3. 54
X = 34. 75

So a 35 tooth gear should do the trick.

Or, using your final drive ratios,

X = 30 * 3. 8 / 3. 3
X = 34. 55

Again, a 35 tooth gear should be OK.

Your other option is to use an Abbott ERA to correct the signal out of the sender. The Abbott would let you dial the correction just about dead nuts on.

Fest3er

 

[SOOT]

The sensor in top of the diff is for your ABS I would'nt think that it would need to be changed.

 

[RLC77]

respeedo gear)

thanks for the info guys. hey fest3er, where do i get the speedo correction unit?

 

[fest3er]

Re: respeedo gear)

Originally posted by RLC77
thanks for the info guys. hey fest3er, where do i get the speedo correction unit?

Most any speed shop should have them. Rickson truck in MD (they make 19. 5" wheels for Dodge and other makes; 1-800-587-7633) also sell them.

Fest3er

 

[Todd T]

can someone help me find the calculation Robert spoke of in issue 32? i cant find my issue 32. to make things worse the outside mailing cover of issue 33 says it was issue 32???@#$%



with the 305's i am running 2000 rpms and the speedo reads 74MPH. what is my actual speed? or what tooth gear do i need to order?



thanks gang

Todd



ON EDIT; i think i found the conversion. i need a 34 or 35 tooth gear, right? anyone know what this would set me back?