How to recalibrate your speedometer after changing tire sizes or gears

should I feel it slide in to place or just have to know when centered ?

I have put in twice, but speedo doesnt work at all now ?
Have you looked at the photos in the very first post in this thread to see how to orient the speedometer gear housing according to the speedometer gear's tooth count? The tooth count affects the gear's diameter so if you don't rotate the housing properly so the speedometer gear engages the pinion gear inside the transfer case, the speedometer won't work. Rotating the housing moves the speedometer gear in or out to properly engage the pinion gear which is what drives the speedometer gear.
 
Yes I looked at the pics and thought I had positioned right, (ty for making me look again) :)
But LOL I went and double checked and I had wrong numbers rolled in down position. Number marking for gear I put in were rolled to top. Must have rolled it when I put gear in. I feel like dummy now LOL BuT speedo works perfect now according to my GPS.
 
My speedo doesn't seem off with 31s and otherwise stock 99 TJ. Would anyone think 31s would be a significant issue on a stock 4.0 sport?
 
Thank you for the guide. I successfully change the gear, but a big BUT happened, the bolt was so rusted that the head of it broke. now I cannot put back the wishbone clamp
 
So I did this this week. My 03 Sport has the original 3:07 rear end but I have 18" JK Sahara wheels, 32 inches total diameter. The chart calls for a 26 tooth gear.

I was replacing my front end so we already had the beast up on the lift. It took about 10 minutes to replace the gear. Previously, when the speedo indicated 50, I was doing 65. Now, we're dead on the money. Easiest fix to a vehicle ever.... Thanks......
 
I have the HealTech SpeedoHealer thing. I bought it off of Ebay for $140. I does work and it isn't as difficult to program as the instructions make it seem. The only negative I see it that you have to plug that their harness between the factory harness by the transfer case which causes more wires and more exposure to getting it caught on something. You also need to bring the wire to the controller up into the engine bay, again, more wire (I don't like wires). It does work however, and it works well. It also has an "A" & "B" program so if you have two different set of tire with different sizes, you can change your speedo with a push of a button.
 
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One thing to keep in mind is that the speedometer gear housing moves around like a cam, in that as you rotate the housing it moves the speedometer gear either closer to or further away from the pinion gear underneath. That's why it has different rotational positions marked on the tcase housing depending on the speedometer gear's tooth count.

So if the speedometer doesn't work after installing a new gear, you likely don't have its housing rotated far enough so the new gear can engage the pinion gear. Rotate the housing a tad more. I've had to do that both times I replaced the speedometer gear.
Hi Jerry,
I know this is an old post, but hoping you can answer this. I see where you say to rotate the housing a bit more to get it to grab. If you do that, will the teeth of the bracket no longer be aligned with the grooves of the housing? Getting ready to do an axle swap and looked at my speedo gear housing, and the two bracket teeth are not in the grooves/notches of the housing...off about about a half inch or so. Did the prior owner goof, or is it due to what you said above?
Thanks!
 
Maybe I missed it, but were can I purchase or order my Speedo gear? I need a 31