My understanding of the automatics (in a car) was that they were more consistant in their shifts for an "average driver", but a "very good driver" in a manual would be quicker.

As far as "big trucks", my own personal preference has been for the Fuller Road Ranger series of transmissions, specifically the 13 and 18 speed series. I have used their 10 and 15 speed models, but not the new Super 10. I have also used the Spicer 1420B transmission which is a 20 speed (14 speed progressive), but I found it slow and clunky, not near as smooth as the Fullers.

The last truck I owned was a Kenworth W900 Aerodyne with a 600 hp Cat, Fuller 18 double over, 3.42 rear ratio, and 11-24.5 rubber.
The combination gave me excellent low coverage for starting out of a hole loaded at 120,000 lbs gross (Canadian loads), and the top gears allowed me to cruise at 1475 rpm (best B.S.F.C.) for the Cat. Three gears down from top (direct gear) gave me 55 at 1475, 1st over gave me 65 at 1475, and top (2nd over) gave me 75 at 1475 (going home gear). The axles were rated at 12,000 front and 48,000 rears (Eaton front, Rockwell rears).

What I really liked about the Fullers (13 and 18s) was the equal steps between gears (about 17%, if I remember correctly) which gave about a 300-350 rpm step from gear to gear. The 18, I enjoyed the most because it allowed you to shift (depending on load and conditions) like an 8, 9, 13, or 18 speed.

The only time the clutch was used; was for selecting reverse, or starting off, after that, the "2 finger technique" as described earlier. As long as you were smooth and paying attention, you would not get the nasty torque reversals in the driveline from a sloppy shift that you would not get from the 10 and 15 speeds.

With that combination of power and gearing, I would start in low gear every time, loaded or empty; easier on the driveline and clutch. The driveshaft was spec'ed heavy duty, the u-joints were standard duty to allow for a "fuse" effect. I always carried a spare u-joint, never had to use it, it was still there in the side box when I sold the truck 5 years later.

I haven't tried the new autos yet, maybe some day.

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Mithra

93 sl600
93 600sel

A mercedes is an inanimate object and therefore must respond to logic and reason.