Hard shift from 2nd to 3rd

[SALTY METHODS]

I've been having an issue with a hard shift from 2nd to 3rd. If I give it a pretty good acceleration, it will wind out a bit then hard shift. I was told by friend that he was having the same issue on his Chevy truck and found that he was low on tranny fluid. So I checked mine to find that mine is overfilled. Can that be the issue? Or an issue? It's way beyond the "hot" fill mark. I haven't been running it so the engine/tranny is cold.

Any suggestions would be greatly appreciated. Thanks!

1998, 170K+ miles.

 

[Spike555]

It can cause issues if it is to full because the transmission has to work harder to push the extra fluid around.
Drive it for 5miles or so and get the transmission nice and warmed up, then with the engine running check the fluid level and drain off any excess.
It’s okay to be a frogs hair over full, but not by a quart or more.
Checking the fluid level when cold without knowing if it is at the correct level will give you a false reading.

Once you know for the fat the fluid level is correct THEN you can check ti when cold and on level ground. Just mark the dipstick with a screwdriver pulling a scratch where the fluid level needs to be and then when doing your weekly under the hood check you can check the trans fluid level with the engine being cold. No need to wipe the dipstick even.