Ronmar
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Well with Allison doc you can program different target and max RPMs, but if you have 2:1 hubs/7.8:1 axle ratio, it probably won’t shift any smoother until you put 2.5+ tons in the back…If this is the case then can I program the TCM for softer shifts or different RPMS ?
The Allison is constantly learning/refining its shifts, its base program looks at the engagement speeds and amount of slip and remembers this for the next time to try and improve it. That base programming was made to accommodate a wide range of real world gear and load configurations, and not our product of the mythical land of MILSPEC. In the end it can only engage a clutch so slowly under light load, so the clutch discs lockup almost immediately and the shifts are harsh. Our 2-3 shift has a double wammy, in that as soon as it meets a low enough converter slip, it brings on converter lockup. Low final gear = low slippage and almost immediate TC lockup upon the shift into 3rd…
Add weight or change the final gear ratio to something more common and it then can adjust the clutch engagement to allow for a more comfortable amount of slip And more comfortable shifting…
you really want a ton or two in the back to balance axle weights anyway…