UPDATE - NEW INFO - Tire pressure recommendation - 1999 Diplomat - new Hankook tires

[FLynes]

1 hour ago, Tom Cherry said:

...The other rule…whatever speed you shift into top gear 4 - 5 on the lower Allison’s or 5 - 6 on the MH3000 or higher….one or two MPH above is your sweet spot…for FUEL EFFICIENCY...

Side tangent, just for clarification, the MH2100 officially became a six-speed in 2006, but I can tell you that ours goes through six gears, when I'm accelerating...two of them (2/3 shift) are almost instantaneous.

[96 EVO]

6 minutes ago, FLynes said:

Side tangent, just for clarification, the MH2100 officially became a six-speed in 2006, but I can tell you that ours goes through six gears, when I'm accelerating...two of them (2/3 shift) are almost instantaneous.

Torque converter lockup 🤔.

[FLynes]

6 hours ago, 96 EVO said:

Torque converter lockup 🤔.

Possibly, but I would think the TC would lock up at cruising speed, not hard acceleration. I liken what I feel to the 5R110W in our F350. Ford officially calls it a five speed, but it actually has six speeds. In different acceleration scenarios, and depending on the temp of the engine and tranny, the 5R110W “skips” a gear, thus giving you the feeling of five gears. IIRC, the pattern is 1/3/4/5/6 or sometimes 1/2/4/5/6. Every once in a while I can feel it going through all six gears, so my ASSumption with the MH2100 is that it was shifting the same way as the Ford.

Edited September 7, 2023 by FLynes

[dl_racing427]

I'm not sure about the smaller Allison, but in the larger 3000 series and up, when accelerating from a stop, the converter clutch locks part way through second gear, and remains locked through all upshifts and downshifts until you slow to the point it drops to first gear.
It doesn't shift similar to any common automotive transmission.
This is done to reduce tranny temps and to make the engine brake or exhaust brake more effective.

[FLynes]

1 hour ago, dl_racing427 said:

I'm not sure about the smaller Allison, but in the larger 3000 series and up, when accelerating from a stop, the converter clutch locks part way through second gear, and remains locked through all upshifts and downshifts until you slow to the point it drops to first gear.
It doesn't shift similar to any common automotive transmission.
This is done to reduce tranny temps and to make the engine brake or exhaust brake more effective.

Makes sense, and it's probably what I'm feeling.