Speedometer Inaccurate

[Hybrid455]

My speedometer is reading about 10% slow. If it reads 50 your actually going 55. The Speedometer driven gear is a 16 tooth. From what I've been able to research this is a very commonly used gear. It seems to be in all these pick ups. In order to speed the speedometer up I need a smaller tooth count. No prob right.... just change the gear....that's where the shoe pinches. A 16 is the smallest available from Ford. Why would Ford allow adjustment one way but not the other? Anyone been through this and what's the easiest fix? Specs in signature.

 

[Fishin76]

smaller tires?

 

[Optikalillushun]

did u do the formula right?

http://fullsizebronco.com/forum/showthread.php?t=109671&highlight=speedo+gear

 

[Hybrid455]

did u do the formula right?

http://fullsizebronco.com/forum/showthread.php?t=109671&highlight=speedo+gear

I guess from what I can see I need an 8 tooth drive gear with a 17 tooth driven gear. Not sure what the drive gear in my transfer case is now but if the link is correct it must be a 6 or a 7. Thanks for the link.

 

[Optikalillushun]

no problem. i went through this when i up'd my tire size. the speedo gears are real cheap at the Ford dealer...like $3.