Speedo correction assistance

[Speedwagon]

So I've already corrected the speedometer on the truck once when I got it. I went to the 16 tooth gear, which is the smallest one listed on the tech library.

Since I just got done lifting the truck a little bit, I was thinking of swapping to 15" wheels when these tires wear out. Doing that, I think I can safely fit 30" tires with no rubbing on this truck. BUT, if I do this, my speedo will be off again, and the correction formula says I would need about a 14 tooth gear now. Is this available anywhere? Or is there something else I will have to do?

And how will a '92 3.0 2wd 3.73 rear end like a 30" tire?

 

[rickcdewitt]

http://www.rrorc.com/forums/showthread.php?t=24206 are you sure your truck is accurate as it is? i would want radar confirmation before putting all my faith in an equation.

 

[lil red]

next time your in a small town, ask a cop to clock you
im not sure if mine is correct either ,so im going to run my truck exactly to the speed limit on my speedo, and see what it is from the radar

its an almost error proof method, and a good way to make sure youre at the correct speedlimit when driving

 

[kunar]

i use a hand held gps to double check my speedometer in all of my tucks

 

[Chris.S.]

i use a hand held gps to double check my speedometer in all of my tucks

^^
same except I use my vehicle mounted GPS to check it, there's about a 2 second lag on it though.

 

[Speedwagon]

I've used GPS, a stationary radar station, and timed myself on the highway. Yes, I am very close to accurate right now.

 

[Speedwagon]

So, the only resolution is to break open the trans and change the big gear?

 

[rickcdewitt]

So, the only resolution is to break open the trans and change the big gear?

you'll have to find out what is available for the 2wd before taking it apart. that chart is for 4x4s so the drive gear is different.call ford do a little research

 

[Earl43P]

So, the only resolution is to break open the trans and change the big gear?

Not at all.

Have you gone to the Ford dealer parts desk?

I had to do that on my 83 and "the old guy" knew exactly where the gears were on the shelf. The young kid reading the computer screen, not so much.

I'd see if Ford has a 14 tooth. May help to take (one of) yours with you.


Your acceleration performance is going to suffer with a larger tire, no doubt about it.