Hard shifting transmission

I have a '96 2500 with the 7.4L engine. I have never had trouble with the transmission but I recently had it serviced (flushed and re-filled). It was fine for a few days, then it started shifting extremely hard (fells like you got rear-ended), especially into overdrive. It is random and seems to have no pattern, but when it happens, I check the mirror to see if I left anything on the road. Cold, hot, towing, driving down a hill, doesn't matter. Completely random. Once it starts, I have the problem until I turn the truck off and let it sit.

Ideas?

Any codes?

I have a '96 2500 with the 7.4L engine. I have never had trouble with the transmission but I recently had it serviced (flushed and re-filled). It was fine for a few days, then it started shifting extremely hard (fells like you got rear-ended), especially into overdrive. It is random and seems to have no pattern, but when it happens, I check the mirror to see if I left anything on the road. Cold, hot, towing, driving down a hill, doesn't matter. Completely random. Once it starts, I have the problem until I turn the truck off and let it sit.

Ideas?


this is so common...when old high mileage vehicles get the flush treatment all that crap in the torque converter gets into everything..I believe this is done to get more transmission work..

droping the pan replacing the filter with the correct type and using the new dexron VI fluid is all that is needed..

what you have is slippage,,,this then is causing the computer to command maximum pressure,,,then the harsh shift..on vehicle shut down this all resets...

Great feedback! I'll give it a shot this weekend.
Thanks!