I have a John Deere 4840, which we use to haul silage wagons down the road, that shifts hard through all gears, going from 7th to 8th or goin eve goin back down from 8th to 7th. It literally pulls you off the seat, it doesn’t matter if the clutch is doubled, accelerated, slowed down, nothing seems to help.
I have checked the transmission pressures and they have told me the pressures were fine. I have flushed the transmission and the oil seemed to have some water in it, I put in new oil and filters, ran it for 100 hours and then changed the filters and cleaned the screen again.
I’ve run it another 100 hours and it still doesn’t look any better. I know our 4020 stem derailleur has a set screw that adjusts for heavy tillage, or smooth shifting. Thanks.
The 8-speed shifting is pretty rough compared to the newer transmissions. They are quite rough especially between 2 and 3, 4 and 5, 7 and 8. For road travel when shifting between 7 and 8, adjusting the throttle immediately before shifting makes a difference, this takes practice, it was always easier with the foot throttle that was standard on the 20 series.
For example, on the 7th, you would go to full RPM, then you would pull the throttle lever almost to the 1200 RPM position and then you would shift to 8th, doing both operations very quickly. Doing the opposite when downshifting. This will help smooth the gear shifting at the top.
You should not use the pedal when changing gears in general, that pedal is for use when maneuvering in tight spaces, that’s why it is called the “forward pedal” and not the clutch.
The eight speeds only change abruptly. Big jumps in the ranges. The heavier the tractor, the more it shows. When we looked at the mixer tractors we drove a John Deere 4840 that was dualed up and weighed down pretty heavy. I thought I was going to break my neck when I changed that thing. The 4850 with the 15 spd is much smoother but still has the jumps of 15 spd.