Hi All,
My speedometer reads 51 mph when the truck is doing 65 mph. The only thing new is the vss sensor on the T case. I have not had the rest apart. Ideas?
Thanks,
Mike

 

Do you know for sure that the transfer case, and the differential gearing have not been changed at any point?

If they have, then the gearing in the TC is probably off, and you need a new ratio adapter. I just swapped from 4.10's to 3.54's on my crewcab, and had to order a +20% ratio adapter.

Here's what you do....Crawl under the truck and remove the VSS, and any ratio adapter that might be there. Then re-install the VSS straight onto the transfer case.

Now use some form to go out on the road and hold a steady 50mph, and record what your speedo is actually register. From there you can figure out what ratio adapter you need to order.

I got mine through these guys....

http://www.transmissioncenter.net/sp...n_______va.htm

 

Thanks for that info. I will try it. I got the trans and transfercase from another truck. I don't know what the other truck had. I will try this.
I appreciate your help,
Mike