Got 4.10's, now what about the speedo?
 

in my 97 scab 4x4 i got a 4r70w from a 98 with 285 75 16 bfg at's and now 4.10's... now my speedo is wayyyy off anyone have any idea on how to solve this problem????

Unfortunately there is no correction for your year truck.

You can change your vss driven gear and get close. Very easy to do.

Item # 82x: http://www.transmissioncenter.org/Fo...eter_Gears.htm

i know i need a new speedo gear thing but i dont know what size.. that gear you suggested says 4.10's but doeasnt compensate for the 33 inch tires.. in the calculator area at that site the highest is like 26 or 28 inches... btw its reading about 5.5 mph off

Your only option is to take that gear out. Its super easy to do. Just lay up under neath the truck and its the furthest bolt along the trans on the drivers side headed towards the rear of the truck. Just unbolt it and pull it out and remember the color, then stick it back in. At that point, you can call ford racing and tell them and the will get you the gear you need. Or they will tell you if that is as close as your going to get. I have 35s and 4:56s on my truck, and have an off speedo. My speedo reads 75 when I am really doing 70. The only thing that will get my speedo closer to correct would be larger tires.

5.5 mph at what speed? 5.5 mph at 60 mph with all of the variables in play, may not bee that bad?

The stock vss gear is 20 teeth - orange one.

if i remember right i thought it was blue when i put my trans in but im more than likely wrong on that. yeah the speedo reads 70 on the dot and the sign thingy flickers 64/65... ill try the dealership but its a chick at the counter and shes the biggest idiot ever so hopefully she has a book cuz she wont know a thing.

Get a GPS. thats what pretty much everyone I know did.

I still have stock gears and when mine says I'm going 70 I'm really going about 79/80. I plan on going up to 4.88s. anyone have this set up on 38s and know what their speedo says compared to actual speed.

yours is computer controlled not like the 97/98 with a gear and all you need is a tuner or custom tune to change tire size if im not mistaken