New here. I recently swapped my 3.23 ring and pinion to 3.73 ratio and went through much grief with ABS warnings and harsh shifting before I finally found a fix. I thought it was worth sharing because after much research I have not come across a solution shared by someone else with the same experience. I have an 07 Classic model 1500 5.3l flex with 4L60E 2WD (Z82/Z85). I thought I could simply install the gears, purchase a Hypertech programmer, and change the settings in the computer. While this corrected the speedometer and shift points, this did not satisfy the ABS module. Apparently the computer does not send the re-calibrated information to the ABS module, so it thought the rear wheels were spinning faster than the front even after reprogramming the computer. So, I reset the computer to factory, purchased an Electronic Ratio Adapter (ERA) from Abbott Enterprises and installed this in-line from the VSS. This seemed to have corrected everything until the first long trip I took. Suddenly, the transmission began slamming every gear. It turns out that some genius decided one year to add an input shaft speed sensor to the 4L60E. Dialing down (re-calibrating) the VSS with the ERA gave the computer the impression that the output shaft was spinning slower than the input shaft (when at 1:1) which triggered a component slippage code. The default in the computer for this situation is to apply FULL pressure on all shifts thereby making an attempt to break metal components vs. burning easily replaceable clutches (which REALLY sucks when you consider a few of the weaker components common to the 4L60E). Fortunately, I was able to remove the ERA from the VSS before destroying the tranny.
Now the fix:
The ERA is capable of being set for A/C or D/C signal re-calibration using four pins set on or off (Abbott Enterprises was extremely helpful by email and always responded timely). I set it for D/C signal and placed the ERA in-line in the signal wire from the computer VSS out to the ABS module and calibrated for the change to 3.73. Then, I tuned the computer with the Hypertech setting it for 3.73 ratio. Finally - all shift points are correct, the speedometer is correct, no more ABS lights, and the ABS warning no longer chimes 33 times EVERY SINGLE TIME the truck is re-started.
At one time it was possible to pay your stealership to reflash the computer and ABS modules, but the ones around here all refused claiming that they cannot make any alterations to the vehicle beyond the way it came from the assembly line, even though 3.73 gearing was a factory option. However, with the Hypertech and ERA I have the option to install other ratio gears and re-calibrate in the future. Please share - I am hoping to save others valuable time and money performing what used to be a simple task.
