So what is the thinking on the use of the clutch - and not using it.
While heavy truck transmissions (such as the Fuller found in many over the road tractors) are designed to be shifted without benefit of the clutch, the M35 (entire G-742 family) is NOT a heavy truck. It is, by definition, a light-medium truck. Accordingly, it has light, medium components.
The engineers at Reo Motors Inc, who designed this thing back in 1949, and literally wrote the book(s) on them likely no more about their design, engineering and operation than any of us. EVERY operators manual written for these trucks - TM9-819 June 1950 TM9-819 (Jan 1952), TM 9-8022 (1954), TM-9-2320-235-10 Dec. 61, TM-9-2320-209-10 Feb 65, TM-9-2320-209-10-1 Sept 1980 says use the clutch every time.
Along the course of the way, these manuals, by contract, were revised and updated by automotive engineers from Studebaker, Kaiser-Jeep, and AM General, with input from a whole lotta folks at Aberdeen Proving Ground and Yuma Proving Ground - if there was a better way to operate the transmission and clutch, I gotta believe that they would have found it!
Since my little collection of manuals spans 30 years, and they keep saying "....
depress clutch pedal, and move transmission gearshift lever to next speed......" ((TM 9-819 Section III, paragraph 42, subparagraph (5)) or "As the road speed increases with acceleration and approaches the maximum speed (indicated on the instruction data plate),
depress the clutch and release the pressure on the accelerator. Move the transmission-gearshift lever......." (TM 9-2320-209-10, Feb 1965; Section III, 44, subparagraph h) - I suspect that the idea is to use the clutch.
I've done this for the past 15 years or so with my little fleet of deuces, and have yet to have to replace a clutch (other than those trucks that have needed them when I got them).
Must be something to this.............
Best wishes,
David Doyle