My trucks speedo was 8 mph hour so I called dodge and they sold me a 30 tooth gear, which I was told is for 265/75/16.
The truck had a 31 tooth in it before. Now it seems worse 8mph before 10 mph now.
Is there anything else that controls speed?
The truck is a 97 4x4 5 spd. it has 265/75/16s. It has a 241dld transfer case in it.
I need to get the speedo fixed fast. I am going camping in a month.

 

What gears do you have? If you have 3.54's it should be right, but if you have 4.10's it should be a 35 tooth gear. That would make sense based on how you describe what has happened so far.

Your speedo will be off by a percentage, not a set MPH.

 

It has 3.54s in it. At 30mph on my speedometer the radar said I was doing 20-21mph, thats with the 30 tooth gear.
The 31 tooth gear read 22-23 mph when speedo said 30.

 

might be a dumb question...but are you sure it was a 31 tooth gear?

brett

 

Yeah, Dark Green and it says 31 right on it. The new one is a 30 and its yellow.

 

so was that a "yeah" it was a dumb question?

brett

 

No, Its just stupid things on my truck that drive me nuts.
I appreciate all the help.

 

Try checking out the tach. Here's a helpful link... http://www.ringpinion.com/Calc_RPM.aspx

265/75/16s are 31.65" diameter. With a NV4500 (0.74 OD) and 3.54 axles, you should be rolling 1669 RPMs at 60 MPH.

 

Here's a good calculator that you put in ALL your own info... unfortunately the tire widths only go up to 285.

http://www.merkurtech.com/merkurtech...ors/rpmmph.php

 

Cool link. It goes to 7000 RPM, we won't be needing that
Here's the Dodge NV4500 info... Gearing: 5.61, 3.04, 1.67, 1, .74, R 5.61
http://www.novak-adapt.com/knowledge/nv4500.htm