30 vs 33" on a '98/5.4/3.73's-What TransSpeedoGear?

Title says it all-I don't want my Ford guy guessing. With the 33's my 3.73 gears effectively are reduced to a 3.41, if that helps

 

When it comes to VSS gears, it is pretty much truck specific. One truck may have a gear with 20 teeth, while another may have one with as many as 24. My truck had 21. I also went from a 30 to a 33, and it threw my speedo off by about 8 mph at 70. I went with a gear with 19 teeth, and now it is almost perfect (less than 1 mph off). If I had to guess, you will also subtract 2 teeth from the number of teeth you have now to decide what new gear you need. Just ask your service guy at your dealership. They should be able to help you. If not, though, just try one with 2 less teeth. These gears are only 5 bucks apiece, so if you are a little off one the first one and need to adjust the speedo a little more, it won't break your wallet to get another.

 

What was your gearing...?

 

I have 3.55 gears, so your VSS gear will probably have a different # of teeth than mine. Maybe one or two difference.

 

Might be an apples to oranges comp, but I have 3.55's and went from a 29" tire to a 31" (235/70/16 to 265/75/16) and my stock VSS gear was a 20 tooth. I dropped down to a 19 and my speedo/odo is just about bang on now..... Well, I'm off about 1/10 of a mile every 10 miles now..... Close enough for me.....

Good luck!

Mitch