As an owner of a B1 truck with an original 4 speed crash box (aka non syncro tranny with compound low) one story you hear is you can shift without using the clutch. Having learned to double clutch to avoid the "grind them till you find them" syndrome of shifting I have to say I was always intrigued by the myth of clutchless shifting. For our owners who always lived in the world of fully synchronized transmissions, double clutching is the technique used to shift a transmissions with "straight cut gears' or no synchronizers. Internally the transmission is pretty simple and very reliable in service.
To double clutch you use the clutch normally to get rolling and when you are ready to to shift your depress and release the clutch once to take it out one gear and a second time to go into another the next gear. The process basically slows down the shift so the gear speeds match and allow them to slide into the next gear. Downshifting is similar except you have to remember to bring up the engine revs as you go into the lower gear.
But what about clutchless shifts? Well, as professional OTR drivers know it is not a myth but a useful technique to drive your truck with less wear and tear on the clutch. Success is all about getting the engine speed right and feeling the gears as you slide them in the gearbox. Again use the clutch normally to get rolling. As you near the shift point lift off the gas slightly and slide the shifter into the gate for the next gear. As the speeds match the shift will smoothly drop into the next gear with no grinding and no clutch needed! Don't be frustrated if the first few times you miss and grind the gears. With a little practice you will be able to tell with engine speed and feeling it in the shift lever when it is time to shift. Downshifting is also possible but requires a little more finesse with engine speed and shift lever. Remember since your are going down in gears you need to raise engine rpm to match the the gear when you downshift. So instead of a slight lift off on the throttle you need to give it a little bump up. Again with the gear speed and engine speed match you can fell it in the gearshift lever as it will easily slide into gear without a grind.
And what about the compound low (AKA, granny gear)? It's function is to help you get moving when you have a big load on board. A while back I had half a yard of sand loaded in the bed. When I started to pull out of the loading area in first it was immediately evident I would have to slip the clutch quite a bit to get rolling. Dropping into compound low we just pulled out like a normal start, just slower. Once we got past the the initial start up resistance from a dead stop it was easy to drive.
Have any of you mastered the art of clutchless shifts?