DID GEAR SWAP FROM 3.21 TO 4.10 ON MY '07 AND DEALER SAID HE CAN'T FLASH FOR GEAR CHANGE, ONLY TIRE SIZE CHANGE. IS THAT RIGHT?

 

Get a Procomp Accu Pro OBII port programmer. It is super simple to use and will allow YOU to adjust tire size and or gear ratio. It will also automatically adjust your shift points if you have an auto

 

As long as your vehicle knows how fast it is going isn't that the main thing with the shift points?
The computer would be getting an accurate speed signal, and an accurate RPM since it pulls it from the engine. I think that all JK's you buy stock are just flashed for tires, and gear ration has nothing to do with it.

 

This was discussed awhile back in a thread long-lost to the bit bin. The conclusion was if you want an accurate speedo and related items (odometer, trip computer, etc), you need to program in the gear ratio. I can assure you I had that option when I uploaded the Hypertech firmware into my JK.

As for the Hypertech storing the serial number: I've never tried to reprogram another JK, so I don't have personal experience with that. But, I've read that some of the initial programmers could be used on multiple vehicles, but not the Hypertechs produced later.

 

The Hypertechs require that one vehicle be programmed back to stock before it is usable for another vehicle.

 

You should call around to other dealers service departments to see what their answer is. It sounds like the dealer you went to is not too knowledgeable about JK's.

 

I don't know why dealers have to be such a pain. I mean come on, work with us!

 

As best as I can determine, the transmission output shaft speed sensor sends a signal to the Transmission Control Module, where it is used in various calculations. One of the things the TCM does with the signal is it sends it to the Powertrain Control Module, where it is converted to a vehicle speed signal. The PCM sends this speed signal to the instument cluster, which tells the speedometer needle where to point. The cluster receives the signal from the PCM and repositions the needle 11 times per second.
Based on this understanding of where the vehicle speed signal originates, I believe axle gear ratio is every bit as important as tire size in determining proper automatic transmission operation.

 

You nailed it ronjenx

 

410 Gears are stock in rubicons it seams he could help you out if he wanted to.