While trying to fix the shifting issue on my 1997 f-150 v6 automatic. I turned on my GPS (MAPS) and viewed my speed. What I found is my speedometer is reading high by about 9%. If I am doing 55 by the speedometer the GPS is reading 63 mph


My question now is what controls the speed reading from the tranny?

 

Do you have stock size tires on the truck? Has the rear gear been changed?

 

stock tires
I bought the truck used from a commercial fleet. I think its all stock

 

You need a different gear on the vehicle speed sensor. Something has been changed, probably the rear gears.

http://www.transmissioncenter.org/Fo...eter_Gears.htm

 

I would have a buddy drive alongside you, say on the freeway for a bit, check that also.

 

Great link!! I'll check the rear final drive ratio and pull the speedo gear to see witch way to go on the speedo gear.
I have a project that I am doing a trans swap on and the link is just on time for that project too.


Thank you

 

My wife clocked me and she thinks I am a speed demoed. If I am doing 65 she says I'm doing 75