A 17,400# truck should require 3,021# of thrust to crawl up a 10* slope. With the 70/30 torque split in 2nd gear, thats,~453# for each front tire and 1057# for each rear tire. So 1057# times 1.942’ tire radius = 2053ft/lb on each rear axle, so 4106 total out of the rear diff, divided by a 3.07 diff = ~1370ft/lb from the rear driveshaft to produce that much tire thrust and about 647ft/lb from the front DS. Thats ~2015ft/lb total from the transmission to make ~3000# of thrust. With a 4.18 total ratio in 2nd gear and considering gearbox losses, thats ~540ft/lb out of the torque converter into the coupled 2nd gear ratio.
Here is where the math gets a little muddier… Low-mid range torque converter multiplication is a little more difficult to estimate as the multiplication increases with the difference between input RPM and turbine/output RPM. And of course the magic of the TC is it will match output to load. The 275hp 3126 tune will deliver from ~400-800 ft/lb between 800 and 1450 RPM? and the torque it delivers will mix with that variable torque multiplication until it reaches stall or the turbine output shaft starts to rotate. But since the required torque of ~540 ft/lb falls in your available range of 0-~1600 ft/lb it obviously moves. If we know the RPM it takes to start moving on that 10* slope, we can estimate engine produced torque, and then estimate converter multiplication at that RPM difference when the truck just first starts to move. In the end it should only take about 1/3 of what you are capable of delivering into the gearbox…
You want to advance the pedal slowly, as it is a speed selector not a throttle. The pedal tells the governor or ECU what RPM to run at, and it in turn delivers fuel as it is “programmed” to achieve that commanded RPM… if it sees a big difference between actual and commanded RPM, it will throw a lot of fuel at it making it difficult to capture the RPM when it first starts to move on the slope…
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jk