Can anyone tell me what the ratio of the speedometer reducer box itself is? The truck is a 92 w250, getrag, 205, 3.54's. Thanks ahead of time guys.

 

I usually use GPS to get a known accurate speed and compare to indicated to calculate error. What I would do is connect the speedo directly to the output of the transfer and compare indicated (speedo) to actual (GPS) and calculate your percent error. Once you know that, you'll know what reduction you need. There are other variables (2wd getrag has several different drive gears that can be installed, for instance) that make this the best way to figure out what you need. These guys can help too;

http://www.transmissioncenter.org/sp...e_and_jeep.htm

 

I didn't consider that. Thank you. I was wondering because I can't find one and mine is missing (new truck). I do have 4 diff ratio boxes that thread on sitting in front of me though. They are all for a John Deere tractor. Just a thought as they are about 10 bucks each on ebay.

 

Mine is an auto and it was 1.3046. Couldn't tell you if the manual is the same. Give Kerry a call @ 1-888-877-1008 and he can hook you up with any ratio you need. My stock r/a was half plastic and half aluminum and the plastic part broke. The ones from PATC are all aluminum and you can even change the offset for clearance if needed.

 

I appreciate that. I will call in the morning. Arkansas troopers give ya the stink eye for speeding.

 

jbawden has the right idea, let your GPS be your speedo

my GPS tells me that my truck's speedo is 5 mph too FAST at highway speed (less at lower speeds). the PO was running 33 x 12.5 x 16.5s on the truck, now I'm running 245 75 R16 snows.

where is the adjustment for the speedo, and is it worth fooling around with those little plastic teeth?

 

The only actual adjustment is changing the drive r&p in the transfer case. I'm just OCD about everything in my truck being funtional. That's why I want to fix it. And GPS in my area is a B&E magnet.