Ability to alter 4wd LOW t-case ratio
Those of us in the off road community have been saying how nice it would be if HPT gave us the ability to dictate the 4LOW ratio used to determine automatic shift points when not in 1:1. The common GM 4wd LOW gear ratio is 2.72:1 and I think that's just assumed by the software or the PCM/BCM (I don't know and would actually like to know what piece of hardware controls this).
However, some of us are using 3:1, 3.5:1, 4:1, 4.3:1 and so on. Factory Wranglers even come with 4:1 (those equipped with the NP241OR transfer case) so it's got to be a value that SOMEONE entered at one point to tell the tranny to expect higher RPM's and lower speeds.
I'd imagine the field could look something like this:
On our 4wd-equipped automatic vehicles, it's my understanding that the PCM receives a signal from the 4LOW shifter and grounds pin 16 (I'd like to talk to someone about this 'fact' actually) which is kind of like a performance/tow-haul mode button to tell the PCM you're now in 4LOW and to shift differently. I'm still learning about this but those of us who have a t-case different than factory or perhaps maybe even double transfer cases for a 4LOW LOW range could really use this feature.
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Bump for this. Starting a new build in a buggy soon with an LM4 5.3L and 5 speed manual with dual transfer cases and 7:1 axle gears. This would be awesome to be able to calibrate for because most of this buggy's operation will be from 0-1mph so switching back and forth between the throttle cracker and follower/spark tables is critical.
Originally Posted by Dirthead Racing
