My diff. blew so I had to replace it. My 4.57's is gone. Now i have the 4.10 on the car. How can I calibrate the yellow box to 4.10's since they are calibrated to 4.57's right now??

 

Set the YB to ZERO.

 

Take it off and install the jumper connector supplied with the YB.

 

yep all to zero. Howd you blow your diff?

If im upgrading to 17s how much of a % change should I make, 1 or 2%?

 

^ Or do that (take it off and re-connect the cut speed sensor wire together), unless you plan to change the FD gearing again soon.

 

This is incomplete information. You need to determine the difference in diameter of the new tire compared to the diameter of the OEM rear tire. And you can't do this till you have the complete tire size. Just saying you are going to 17s means nothing.

 

I just hear people saying 1-2% as an estimate/average when they upgrade to 17s? I can check on details later when I get the rims

 

You can't just listen to what people "say" without taking into account the exact details of the tire spec. A difference of 1" in diameter is only about 4%. Most 17" tires used will have much less than this, so it would be insignificant. The natural speedo error would be as much.

 

Even if you got 19's, the speedo would not change at all if the rolling radius of the tires are the same. Tire height (or the distance it covers when you roll it one time) is what affects the speedo.