I do a bit of tinkering with engine and transmission mods (mostly swaps using vanilla content, but occasionally lore-friendly fictional concoctions). The powertrain simulation works fine for most conventional automatic transmissions since they all mostly work the same - however, I have wondered lately how it might be possible to implement an odd feature unique to some Chrysler transmissions developed in the late ‘90s and early ‘00s - Prime gears. Beginning with the 45RFE (a four-speed longitudinal transmission, first used in the 1999 Jeep Grand Cherokee), an alternate 2nd gear (referred to as “2nd Prime”) was used during kickdowns from 3rd or 4th gear. The normal 2nd gear was used during acceleration and 2nd Prime was skipped in the upshift sequence. Ratios are as follows: 1st - 3.00:1 2nd - 1.67:1 2nd Prime 1.50:1 3rd - 1.00:1 4th - 0.75:1 5th - 0.67:1 (2001+ 545RFE) For 2001, a 5th gear was added as a second overdrive, and the unit was renamed 545RFE. Based on the clutch application chart, I don’t believe direct shifts from 5th to 2nd Prime are possible. It appears that downshifts from 2nd Prime to either 2nd or 1st are possible, if necessary. This transmission was later developed into the six-speed 65RFE, 66RFE, and 68RFE. Only the 65RFE retained the six-ratio/five-speed gearset with 2nd Prime - the others used new, true six-speed gearsets. For 2007, the 62TE (a seven-ratio/six-speed variant of the infamous four-speed A604/41TE transaxle) was introduced in the Chrysler Sebring and Pacifica CUV. The additional ratios were provided through the use of a two-speed “compounder” gearset with an underdrive ratio of 1.452:1. It used an alternate “4th Prime” for kickdowns from 6th gear to avoid a double-swap shift of the main four-speed gearsets and compounder unit (curiously, a double-swap still occurs during any shift between 2nd and 3rd). As with the 545RFE, 4th Prime is skipped in the upshift sequence. Ratios are as follows: 1st - 4.127:1 (underdrive 1st of 41TE) 2nd - 2.842:1 (direct 1st of 41TE) 3rd - 2.284:1 (underdrive 2nd of 41TE) 4th Prime - 1.57:1 (direct second of 41TE) 4th - 1.452:1 (underdrive 3rd of 41TE) 5th - 1.00:1 (direct 3rd of 41TE) 6th - 0.69:1 (direct 4th of 41TE) A possible eighth ratio, underdrive 4th, is not used as it is almost identical to 5th/direct 3rd. Based on the clutch application chart, direct shifts to 4th Prime from either 5th or 6th gear are possible - however, I don’t know if 5th to 4th Prime is ever used in reality. Theoretically, it is possible for the transaxle to downshift directly to either 3rd or 2nd gears from 4th Prime. My question is this: is it possible to implement this odd shift strategy in Beam? I know it’s a bit nerdy, but a properly-shifting 62TE would be a perfect addition to the Lansdale, and likewise for the 45RFE/545RFE and the D-Series/H-Series/Roamer.
Custom shifting logic like that certainly is possible with via Lua coding. Some examples of other transmission mods with custom shift logic; https://www.beamng.com/resources/updated-shiftlogic-automatic-transmissions.16947/ https://www.beamng.com/resources/automated-manual-transmission-more.30117/
