Hi all,
Just got new tires on the back end of the truck.
Same size.
Speedometer was running fine before tires were put on.
Small thing though, the truck was sitting up for approx. 3 months on stands while I was waiting to get tires for it. During this time, there were no tires on the back end, and during this time I put it in drive(not my smartest decision, I will admit), just to see what it would do, truck shot up to 45 MPH during idle, I put my foot on the brake and it nearly stalled out the truck when I did that. No idea if it messed up anything, though I am positive it did, because upon driving it today, It will read approx. 2x the speed I am actually going.

Any ideas? Would really like to get this fixed soonish.

Thanks beforehand, excuse my stupidity.

 

Does the speedometer needle stay steady or jump back and forth?

 

Stays steady. Any idea?

 

Just had this discussion over the last two days. Check here!

https://www.ford-trucks.com/forums/1...150-302-a.html

 

Still, your thread didnt really give me any answers.
Same tires.

 

The only explanation I can give is the speedometer head in your dash is messed up. You can correct the speed to a certain extent by changing the speedometer drive gear in your transmission or transfer case if a 4X4. But the gears only have so much variation in the number of teeth they have.

 

Even though it was working fine before?

 

That is a real mystery.

 

Any thoughts?