shiftin problem.... help me out

Sounds like you're shifting way too early. Or taking too long between shifts and allowing your revs and speed to drop off.

Depending on terrain, weight, horse power and road conditions. You might want to rev as high as 1700 rpm before shifting. A cummins engine can take that without issue. Provided your company has not restricted your revs below that. Ours are restricted to 1600 rpm in 9th.

Progressive shifting calls for increasing rpm's as you climb through the gears. While you might make the first shift, almost immediately after the truck starts rolling, the other gears will need a bit more rpm. Too little, you get the hop. Too high, you lose fuel economy.

You''ll eventually get where you don't use a tach. Regardless of engine design. I can easily swap from low rev high torque engines to high rev lower torque engines, with no issues.

If you're shaking during take off. You are in too high of a gear.

 

Well it has been awhile since i drove a Cummings.. I know the RPM's need are lower then a Detroit and cat.. I know the high side you shift around 1100-1300 RPM the low I can't be for sure but i am thinking 800-1000 range..

 

You grab a gear with my cummins at 1300 rpm, you'll be blocking traffic for a long time. Maybe in 5th to 6th...but certianly not 6th to 7th

That would be reasonable with the new high torque engines. But not the older designs which are still being sold in some trucks.

BTW, my cat engine shifted out on the upper side, at 12 - 1300. It was the newer high torque low rpm design...and I miss it

The new Detroit DD15, 1300 rpm will give you everything you need to pull tree stumps.

 

Ok its been years since i used the clutch to shift so can't help allot in that dept. But that is one of the problems i see with the schools they teach you to shift by the tach no matter what the engine sounds like or how much strain its in if its here you shift up or down. Its not that simple either believe it or not no 2 trucks with the same specs will shift right at the same place. If i drove the truck since it was new it will shift better where i have been shifting it all the time. If you get in and try and shift it to your style it will be a fight for a while and you will eventually learn to shift where the truck is comfortable not where your instructor told you too. Just sdjust your shifting to where it will feel comfortable and the jerking and poping was the reason i learned to float the gears with a load of steers on or a load of fuel in a tanker jerking and popping is not what you want to be doing so smooth is the way to go.

 

float it, let the rpm go up till you "feel" yourself not accelerating as fast, let off the gas as you push the shifter toward neutral. if on flat ground you push to the next gear in about 1/2 second or so. if going uphill it is almost immediately (gravity will slow the rpm quicker) and downhill i wait at least a full second, then ease it in there. untill tyou get used to it it might grumble a bit, but dont force it. be GENTLE if it grumbles, when it falls to correct rpm it will "fall" right in.